Glossary(definitions)
Adjusting barrel
A hollow bolt, designed so that a gear or brake cable can run down through the centre of it, but the housing stops inside the head of the barrel. This allows fine adjustment of cable tension without requiring the use of any tools. Adjusting barrels may be located at the end of any run of cable housing. On brakes, their primary function is to permit easy adjustment to take up the slack as the brake shoes wear down. On gear shifting cables, they help fine-tune the indexing.
Adjustable Cup
In a conventional threaded bottom brackets, the left cup is adjustable, and its position is secured by a lock ring. The right cup is not adjustable; its position is fixed, usually by a shoulder that presses against the side of the bottom-bracket shell. The fixed cup is screwed all the way into the bottom bracket, until it runs out of threads.
The bearings of a cup-and-cone bottom bracket are adjusted by screwing the adjustable cup in or out of the bottom bracket shell, and the lock ring secures the adjustment.
Aerial
The branch of riding that is mainly concerned with jumps and off-the-ground tricks.
Aerodynamic
Parts or riding positions intended to reduce air resistance. In most cycling, air resistance is the major limiting factor on speed.
Probably the oldest "aerodynamic" part is the drop handlebar. Many other bicycle parts are available in "aero" versions, including:
• Brake callipers.
• Brake levers.
• Fork crowns and blades.
• Frame tubing.
• Rims (tall, and tapering toward the spoke attachment.)
• Spokes (flat blades or elliptical cross section.)
• Wheels, either disc wheels or wheels with very few spokes (as few as 3 in some cases)
Aero Bars
Handlebars or handlebar attachments that allow the rider to assume a lower, more aerodynamic upper-body position. Most aero bars support the rider's upper-body weight by the forearms, rather than the hands, as with conventional handlebars.
Aero bars make possible a significant improvement in speed, but with less secure control of the bicycle. They also eliminate most of the shock absorbency normally provided by the cyclist's bent elbows, so they are not suitable for rough surfaces. They are not usually allowed in mass-start racing.
Aero bars originated from an attempt to duplicate the "tuck" of a downhill skier. They first appeared in 1986 when Pete Penseyres introduced them in the Race Across America (RAAM).
Although they were an instant hit with triathletes and time-trialists, professional racers were slow to accept this innovation. When Greg Lemond rode Scott aero clip-ons to victory in the decisive final time trial of the 1989 Tour de France, the ice was broken, and few racers will now ride time-trial stages without them. Although aero bars originated as racing equipment, and are particularly associated with triathlons, they have also become quite popular with touring cyclists and randonneurs, as much for the relief that they give to the hands and wrists as for their aerodynamic qualities.
Aero brake levers
Refers to brake levers made for drop handlebars. Older designs had the cables exit up from the front of the brake levers, arching over the handlebars. The newer style, where the cable exits out the back of the lever and runs under the handlebar tape is referred to as "aero" because it eliminates the wind drag of the exposed cables.
Aero levers are generally an improvement over the older type. The pivots are located differently, making it possible to get fairly serious braking from the position where the rider's hand is on top of the lever hood. Non-aero levers would permit the use of this position for gentle deceleration only.
Aero brake levers usually have more mechanical advantage, which is good in general, but may cause problems when they are used with cantilever or drum brakes that require more cable than conventional callipers.
In France, exposed brake cables remained popular longer than elsewhere, because French cyclists sometimes like to transport baguettes home from the boulangerie by resting them crosswise across the brake hoods. The cables help hold the loaves in position.
Allen Wrench
A solid hexagonal bar, usually "L" shaped for leverage that fits into the hollow hexagonal hole of an Allen bolt head.
This tool is sometimes confusingly called a "hex wrench," "Allen key" or "hex key."
Alloy
Strictly, an alloy is any metal that is a blend of more than one kind of metal.
In common bicycle usage; "alloy" is usually a synonym for aluminium.
Aluminium
A metal used for many bicycle parts. Aluminium is light and does not rust. By weight, it is not as strong as steel, but it weighs 1/3 what a similar volume of steel weighs. Aluminium is one of several materials that are quite suitable for making frames.
On virtually all-good quality bicycles, aluminium is used for cranks, chain wheels, rims, handlebars, stems, brake parts and derailer parts.
Aluminium is not suitable for spokes, cables, or highly stressed threaded fasteners in general.
In most English speaking countries outside of North America, they stick an extra syllable into the word, and call it "aluminium".
Different aluminium alloys and treatments are designated by a numerical code, as explained by Jeff Del Papa:
They indicate what other stuff is mixed in with the aluminium. Pure aluminium isn't all that strong. Add some silicon, magnesium, zinc, copper, and other things, and the result will be far stronger.
The first digit tells what "family" it belongs to:
1xxx |
Commercial aluminium (more than 99 per cent Al) |
2xxx |
Copper |
3xxx |
Manganese |
4xxx |
Silicon |
5xxx |
Magnesium |
6xxx |
Magnesium and silicon |
7xxx |
Zinc |
8xxx |
Other elements |
The other 3 digits can be looked up in a table, to tell you how much of each they get, and how good the result is. They are assigned in order requested; they don't have any relationship to how much of each ingredient is used, or the properties of the result. (Unlike steel alloys, whose numbers (1020, 4130, and 4340) include the carbon content.)?
If you see things like -T6, following the alloy series, those describe any heat-treating the stuff got after it was made. Getting this done correctly is critical to the strength of the frame. For most aluminium frames, it is done after the frame is welded, as the heat from the welder will change the metal (usually makes aluminium alloys softer) Heat treating typically involves heating to near melting (900-1000F, it melts around 1100F, your oven self cleans at 800-850), holding it there for some amount of time (for thin tube, 1/2-2 hours or so) cooling suddenly (dunk in water), then a long bake (8 or more hours) at a lower temperature (like 350F).
The different alloys vary in tensile strength, corrosion resistance, welding compatibility, ductility, and machine ability. The densities of aluminium alloys don't vary much at all (under 5%) and the stiffness doesn't change.
Each alloy has good points, and bad points. What counts as good, and what is bad depends on what you are going to do with it. Some very strong alloys can't be welded, so they make bad frames, and great chainrings. Another might give up some absolute strength, but gain some resistance to cracking. One may cost more, but the heat-treating process is cheaper. If you are bolting or bonding things together, you can mix alloys. If you are going to weld, all the welded parts have to use identical filler material, and heat-treating schedule. (So you can't mix 6061, and 7005 in the same welded structure)
It's the designer's job to choose correctly among the various tradeoffs. If the designer chose well, even a not particularly exotic material can do the job just fine. Pick wrong, and even exotic super-alloys will break.
Anatomic
Marketing term to describe a bicycle part that is purported to be better fitted to the cyclists' anatomy than other designs. The term has specific customary meanings in the bicycle industry:
• Anatomic saddles are those with two bumps and a valley between at the rear. This design is usually associated with Avocet, but has been widely copied since.
• Anatomic brake lever hoods are specifically shaped to fit left and right hands. This design was popularised by Modolo.
• Anatomic handlebars are drop bars that have straight sections to fit the hands, particularly just below the brake levers. A Modolo patent covers this design.
Angles
The usual angles that are referred to in frame design are the head-tube (or fork) angle and the seat-tube angle. These angles are usually measured with reference to the horizontal. The typical range is from 68 to 75 degrees.
In general, bicycles with shallower, "slack", "relaxed" angles (lower numbers) tend to be more stable and comfortable. Bicycles with steeper, more upright angles (higher numbers) tend to be manuverable, but less comfortable on rough surfaces. Shallower frames tend to have longer wheelbases than more upright frames; bicycles with shallower head angles normally have more fork rake. All of these factors contribute to the riding characteristics cited.
Anodised, anodising
Anodising is an electroplating process commonly performed on aluminium parts, which forms a thin protective film on the surface of the metal. Anodising is sometimes accompanied by the use of a coloured dye, which gives a lustrous coloured finish to the aluminium parts.
Some rims are "hard" anodised, which produces a hard surface, harder than the natural aluminium, usually in a dark brown or black. This process was popular in the 1980s, as it was presumed to improve the durability of the rim's braking surface, and to make the rim more resistant to cracking around the spoke holes.
Unfortunately, the anodised braking surfaces did not provide as good a grip as natural aluminium, and they presented an unsightly appearance as the dark coating wore off of the sides of the rim.
Even more unfortunately, it developed that the harder surface was also more brittle, causing more problems with cracking around the spoke holes.
Bar Ends
Handlebar extensions, which mount on the ends of a straight-ish mountain-bike, style handlebar to provide extra hand positions.
Base layer
Some riders swear by the benefits of a base layer in addition to a short-sleeved top, even in very hot weather, as a wicking base layer aids the transfer of sweat away from the body. Base layer designed for this purpose are thin and incredibly quick drying. Like a jersey, in order to wick sweat effectively a base layer must fit next to the skin.
Also, an extra layer between you and a jersey provides crash protection as the two layers of material slide over each other, reducing skin abrasion.
Bead
A hoop, usually of heavy steel cable, that forms one edge of a tire. Sometimes made of Kevlar ®, for lightness and fold ability.
Bearing
A bearing is the point of contact between a turning part and a non-turning part. A good bearing assembly has little or no play, and as little friction as possible.
Major bearings on a bicycle are the headset, the bottom bracket and the hubs. There are also bearings in brakes, pedals and freewheels.
Block
- Short for freewheel block; cluster.
- "Brake block" is another term for a brake shoe or pad for rim brakes.
- A "block generator" is a combined generator/headlamp unit, designed to mount on the front fork. It has the advantage of not needing any wiring. Block generators are no longer generally available due to liability concerns. Since they mount to the fork blade, there exists a possibility that, if not properly secured, they could slip down and fall into the spokes, locking the front wheel and causing a crash.
BMX
Bicycle Motocross, a type of dirt track racing, primarily for children. Competitors usually ride 20" wheel, single speed bicycles with a freewheel and a rear hand brake. Races, called "motos" usually last less than two minutes, and feature jumps. High level BMX races mostly hinge on getting a good start off the line, which, for some reason, is called a "hole shot" BMX tracks use mechanical starting gates that fall forward under the riders' wheels when released.
Booster
The bosses of cantilever brakes can flex outward when the brake is applied hard. This contributes to a "spongy" feeling to the brake lever, and, in some cases, the extra flex may permit the brake lever to bottom out against the handlebar.
A "brake booster" is a metal bridge that connects the outer ends of the two cantilever bosses, holding them in position and greatly reducing their tendency to flex under load. A booster resembles an inverted "U", as it curves up and over the tire.
Boss
A bump or protrusion. This term has several specific bicycle usages:
• Cantilever bosses are the brazed-on pivots attached to frames and forks for cantilever brakes.
• Shift lever bosses are brazed-on pivots for down-tube-mounted shift levers. Most newer "road" bicycles have the shifters mounted on the handlebars, so they use the old-style lever bosses as attachment points for housing stops.
• Older style freewheel pullers had two (or four) protruding bosses that engaged the notches of the freewheel body. This system was prone to failure when removing freewheels that were unusually tight. The development of splined freewheel removal systems made this obsolete
Bottom bracket
The part of the frame around which the pedal cranks revolve, also the bearings and axle assembly that runs through the bottom bracket shell of the frame.
A conventional cup-and-cone bottom bracket. The lock ring wrench is about to loosen the lock ring; the pinwrench is engaging two of the holes in the adjustable cup.
A cartridge bottom bracket. The splined tool is shown above the bottom bracket. The crank would need to be removed to actually use the tool.
Bottom brackets come in different sizes, according to the nationality of the frame:
Standard: |
Threading |
Adjustable |
Fixed |
Shell |
|
British |
1.370" X 24 tpi |
Right |
Left |
Standard 68mm |
The overwhelming majority of bicycles in current production. |
Italian |
36mm X 24 tpi |
Right |
Right |
70mm |
Italian and some high-end French bicycles. |
French |
35mm X 1mm (25.4 tpi) |
Right |
Right |
68mm |
Obsolete, used on older French bicycles. |
Swiss |
35mm X 1mm (25.4 tpi) |
Right |
Left |
68mm |
Same thread as French, but fixed cup is left threaded for reliability. |
Raleigh |
1 3/8" X 26 tpi |
Right |
Left |
71mm |
Older British-made Raleigh's, especially 3 speeds. |
O.P.C |
Male threads |
|
Older U.S. bikes, BMX, Juvenile bikes, Department Store bikes |
Standard bottom bracket bearing assemblies are specified in terms of width of the bottom bracket shell (generally 68, 70 or 73 mm) and the length of the spindle (102 - 130 mm.)
Current usage generally assumes that 68 and 73 mm bottom bracket units are for British/ISO threaded frames, and that 70 mm units are for Italian threaded frames.
The spindle length mainly depends on that kind of crank set you'll be using, and doesn't have much to do with the frame. New cranks come with a spec sheet that lists what length spindle they are intended to be used with. Sometimes two lengths are listed. When this is the case, the longer size is for use on frames with fat seat tubes, because such frames put the front derailer mechanism farther to the right than it is on a frame with a standard seat tube.
Braze-on
A small fitting permanently attached to a frame. On traditional steel frames brazing holds on these attachments. But the term "braze-on" is also used for fittings that are welded, glued, riveted and guides, water bottle cage mounts, shift lever bosses, cantilever brake bosses and cable stops. Pump pegs, ect.
Brazing
Brazing is the joining of metal parts by melting a different metal (of lower melting point) that bonds the parts together. Typically brazing involves joining steel parts with molten brass. Soldering is a similar operation, using lower temperatures and different filler metals (with a lower melting point) In brazing and soldering; the filler metal penetrates inaccessible areas of the joint by capillary action.
Bungee, Bunji, Bungie, Bungy...Cords
An elastic shock cord with hooks on the end, commonly used for securing baggage to a luggage carrier.
Bushing
A hollow cylindrical part that connects two other parts, usually serving as a simple bearing. A bushing may have a stepped outer circumference to locate the outer part axially.
Butted
Thicker at the ends. Said of spokes and frame tubing. (Butted spokes are also called "swaged") Butted tubing is usually made with a constant outside diameter, but thicker walls at the ends. The idea is to make the part stronger at the ends, where the stresses are greatest, and lighter in the long middle section, where stresses are less.
Cable
Most modern bicycles use cables to control the gear shifting and brakes. These cables, also known as "Bowden cables" consist of two parts, an inner cable of twisted steel wire, and an outer cable housing. Cables transmit force by a combination of tension on the inner cable and compression to the housing.
Cable Guide
A cable guide is a fitting or frame feature that guides a piece of bare inner cable around a corner. Most multi-speed bicycles have cable guides to get the derailer cables past the bottom bracket
Older derailleur bikes used either brazed-on or clamp-on guides just above the bottom bracket, but newer bicycles have a guide under the bottom bracket.
The below-the-bottom-bracket option has the advantage of being cheaper, and, for some bikes with very small chainweels, it eliminates interference betwixt the rear derailer cable and the bottom of the front derailleur cage. It also makes it slightly easier to clean the frame cosmetically.
The above-the-bottom-bracket system is superior in that the cable is shorter and the loop of housing at the rear derailer is not as tight, since the cable stop is atop the chain stay, rather than beneath it.
Poor lubrication of bottom-bracket cable guides is a common cause of auto shifting. Some bicycles use a cable guide on one side of the seat cluster for a rear cantilever brake cable, rather than use a short length of housing between two housing stops.
Cable Stop
A fitting found at each end of a piece of cable housing. It consists of a socket to receive the housing, with a small hole at the bottom, which will let the inner cable slide through, but hold the housing end rigidly in place.
Cadence
The speed at which the pedals turn, measured in R evolutions P er M inute. Inexperienced cyclists tend to ride in higher gears than they should, pedalling at a slower cadence.
Most experienced cyclists pedal at cadences in the range of 70-90 RPM. This puts less strain on the joints, particularly the knees. Racing cyclists often use even higher cadences for bursts of acceleration.
Cage
• A metal or plastic holder for the bearing balls in a ball bearing. Use of a cage keeps the balls from bumping into one another, and allows the use of fewer balls. In the case of traditional cup-and-cone bearings used on bicycles, the primary purpose of caged balls is to save labour. More formally known as a retainer.
• A holder for carrying a water bottle.
• The part of a derailer through which the chain passes. The front derailer cage is a simple guide; the rear derailer cage contains the jockey pulley and the tension pulley.
• The outer part of a conventional pedal, the part that comes into contact with the rider's shoe.
• The part of an internal gear hub that holds the planet pinions.
• Slang term for an automobile; a "cager" is the driver of an automobile.
Calliper (brake)
A calliper is a measuring device with moving parts that come together to determine the dimensions of a part.
Most bicycle brakes use a similar mechanism to move the brake shoes inward toward the rim, so they are called calliper brakes. A calliper brake uses a single assembly to move both brake shoes together, unlike a cantilever brake that has a separate unit on each side of the rim.
A brake calliper attaches to the bicycle by a single bolt, through the centre of the fork crown or the brake bridge on the seat stays.
Campagnolo ®
The leading Italian maker of bicycle parts. Campagnolo invented the quick release, and was instrumental in the development of the derailer.
Campagnolo parts are so highly regarded that Campagnolo's proprietary dimensions have, in several cases, become adopted as de facto international standards. This is particularly so in the case of headsets.
The Campagnolo headset dimensions are 26.4mm for the fork crown race and 30.2mm for fitting the frame races into the head tube. Other common systems, such as JIS, use a larger diameter (such as 27mm) for the steerer, and a smaller diameter (30mm) for the head tube. These frame/fork dimensions can be easily machined to fit Campagnolo style headsets.
Cantilever Brake
A cantilever brake has two separate arms, or cantilevers, one on each side of the rim. Each arm has pivots on an independent boss, and the two arms are usually coordinated and linked by a transverse (or straddle or crossover) cable that runs above the top of the tire. The transverse cable is commonly connected to the main brake cable by a yoke. In some newer designs, the end of the main cable becomes half of the transverse cable, and a short link wire forms the other half. For details on cantilevers, see my article on Cantilever Geometry
A recent variation on cantilever brakes is the V brake that dispenses with the transverse cable altogether.
Carbon fibre
Carbon filaments used with a resin, in a technology similar to fibreglass. The resulting composite material is very strong in the direction that the fibres run in. Carbon fibre is available in the form of tubing with a woven/braided weave, which can be glued into lugs to build more-or-less conventional frames. A more sophisticated approach is to lay up the carbon fibre cloth in a specific shape, in a mould the shape of the finished bicycle. This allows the orientation of the fibres to provide strength in the direction of the actual stress. Carbon fibre technology shows great promise, but there have been reliability problems with many early models.
Cassette
A cluster of sprockets and spacers designed for use on a free hub. Some of the sprockets and spacers may be semi-permanently attached to one another by bolts or rivets.
Centre-pull Brake
A calliper brake in which the main cable runs down the centre line of the bicycle, using a yoke to connect to a transverse cable. Technically, a normal cantilever brake is a form of centre-pull brake, but the term is normally used to refer to calliper brakes only. This type of brake was popular from the late 1960's to the early 1980's, but is currently out of fashion. Centre-pull brakes are a good choice for bicycles that have a long reach from the mounting point to the rim.
Chain
Modern bicycles use roller chain to connect the cranks to the rear wheel. Chain drives are among the most efficient means of power transmission known.
Chain size is specified by pitch and width. The pitch is the distance between rollers (1/2" on all modern bicycle chain). The width is the internal width where the sprocket teeth fit in. Bicycle chain comes in two basic widths:
• 1/8" chain is used on most single-speed bicycles, and bicycles with internal gearing.
• 3/32" chain is used on derailer equipped bicycles that have more than 3 speeds.
Chains for derailleur applications also come in various external widths. Newer clusters that have more sprockets use chain with thinner side plates and flush rivets.
Chain guard
Any of several types of protective baffle used to prevent the chain from entrapping a trouser leg, or soiling the cyclist's leg or clothing. Getting a trouser leg caught in the chain can be an inconvenience on any bicycle, but, in the case of a bicycle with a coaster brake or a fixed gear, it can be extremely dangerous.
• The traditional "hockey-stick" type chain guard extends from the seat stay forward and covers the upper run of chain, running down the front side of the chain wheel.
• The full gear case or chain case completely encloses the chain. This type of chain guard is, unfortunately, not currently available in the U.S., though they remain quite popular in the Netherlands.
• Chain wheel discs, unlike the above styles of chain guard, are usable on bicycles with derailer gearing and multiple chain wheels. They are primarily intended to prevent soiled clothing, since the front derailer tends to keep trouser cuffs from being snagged. Unfortunately, many chain wheel discs interfere with obtaining the best possible front derailer adjustment. Should the chain become derailed on a bike with a chain wheel disc, it may become seriously wedged between the disc and the large chain ring. Chain wheel discs are rarely found on high quality bicycles.
Chain ring
A front sprocket, specifically of the type that would attach to the crank by being bolted on to a spider.
Chain stays
The (usually tapered) tubes that run from the bottom bracket to the rear fork ends.
Chrome, Chromium
Chromium is a metal, which is used in two ways in bicycle technology:
• As an alloying element to steel, usually along with molybdenum or vanadium. It makes the steel tougher.
• As plating for steel or brass, it has a shiny silver appearance, and provides some protection against rust.
Chrome-Moly
Steel that has been alloyed with small amounts of Chromium and Molybdenum. This is the material used for most high-quality bicycle frames and forks.
Cleat
A leather, plastic or metal fitting attached to the bottom of a cycling shoe to provide positive engagement with the pedal.
• Classic cleats for use with toe-clip pedals had a simple slot that fitted over the rear edge of the pedal. This provided a consistent position of the foot on the pedal, both in terms of centering the ball of the foot over the pedal spindle, and maintaining the desired foot angle on the pedal.
Up until the late '70's, cleats were leather or aluminium, and were nailed onto the bottom of the shoe with many tiny nails. The usual procedure was to have the cyclist ride for a while without the cleats, until the pedal would make a mark on the sole of the shoe. This mark would then be used as a guide to locate where the cleat should be nailed on.
In the '70's, adjustable plastic cleats were introduced, and immediately rendered the nail-on system obsolete...unfortunately, they also precipitated a rash of knee injuries, because riders would adjust them by pure guesswork, and this often caused un-natural stresses on their knees. The invention of the Fit-Kit R.A.D. made it possible to adjust this type of cleat even more accurately than the old sole-impression system.
• Cleats for clip less pedals are made of metal or plastic, and lock into the pedal mechanism. They are adjusted in the same manner as the adjustable cleats of the '70's.
Before the invention of clip less pedals, classic cleats were the only way to provide positive, accurate shoe/pedal attachment. They were rather dangerous, however. If the straps were over tightened, it could become impossible to get your foot out in an emergency, and many embarrassing falls have resulted from this. They also were slippery and hazardous to walk on.
Modern clip less pedals have solved these problems, and, in my opinion, nobody should still be using classic cleats. Now that there is an alternative, they are just not worth the risk.
Clincher Tire
This is the normal type of tire, with a separate inner tube. The tire consists of two hoops called "beads", made of steel or Kevlar cable, which are held together by cloth, usually nylon. The whole assembly is dipped in rubber, with thicker rubber applied in the tread area.
A clincher tire has a separate inner tube, which is basically a rubber balloon. This fits inside the tire, and the tire is mounted on the rim by lifting the beads over the edge of the rim. The middle of the rim makes a sort of valley, and while the tire is being installed, most of the bead can fit into this valley. This gives enough slack to allow the bead to be pushed or pulled over the edge of the rim, even though outside diameter of the rim is larger than the inside diameter of the bead.
Strictly speaking, the term "clincher" is slightly incorrect, as it applied to an obsolete style of tire that had ribs in the edges of the tire that fitted into grooves on the rim, where the tire was folded under the tube. The air pressure in the tube pressed the rib into the groove, and "clinched" the tire in place. People who are fussy about this prefer the term "wire-on."
Other types of tires include airless tires, single-tubes (both obsolete) and tubulars.
Clip less Pedals
Up until the late '80s, the choice was between plain pedals or pedals with toe clips and straps. Since "clip less" pedals provided a way to have a secure attachment to the pedal without the use of toe clips, the name stuck, even though it is sometimes confusing to newcomers.
"Clip less" or "Step-in" pedals use a mechanism similar to a ski binding. In fact a ski-binding manufacturer, Look, made the first successful system. Clip less pedals use a cleat that is bolted to the bottom of the shoe. When the rider steps on the pedal with the cleat, the cleat locks into the pedals mechanism, and is held firmly in place. Some systems hold the foot at a fixed angle; others allow various amounts of "float", or angular rotation of the foot on the pedal.
With most clip less pedal systems, twisting the heel outward disengages the foot. Some of the earlier systems, such as the pioneering Cinelli model, required the rider to reach down and operate a release mechanism by hand. This style is sometimes jocularly referred to as "death cleats."
Cluster
A group of rear sprockets on a multi-speed bicycle. If the bicycle uses a thread-on freewheel, the term "cluster" would include the entire assembly including the freewheel mechanism. In the case of a cassette hub, the "cluster" would only consist of the sprockets and the spacers that separate them.
Compact Frame
Traditional "road" frames have been built with level top tubes since the early 1900s. The influence of mountain and BMX bike design has led to the increasing popularity of frames with sloping top tubes, higher at the front.
"Compact" road frames have sloping top tubes, and are intended to be used with a long seat post. Compact frames are a little bit lighter than traditional ones, but this is partially offset by the weight of the longer seat post. Some riders believe they are stiffer.
Manufacturers like them because they are more versatile in terms of fit. Usually 3 or 4 sizes are enough to fit 98% of customers. This saves a lot of money for a manufacturer who doesn't need to deal with so many SKUs.
Composite
Literally, a material made up of different materials joined together. In bicycle technologies, the most common uses refer to the use of carbon or boron fibre, or fibreglass, bonded together with epoxy resin.
Cotter less Cranks
The modern type of three-piece crank set. Although one-piece cranks don't use cotters either, the term "cotter less" normally refers to three-piece sets.
The bottom bracket axle used with a standard cotter less crank has tapered square ends, which fit into matching tapered square holes in the cranks. The ends of the axle will be threaded, either male or female, and a bolt or nut (called the "fixing" bolt/nut) will pull the crank tightly onto the end of the axle.
The nut or bolt head is recessed into the crank, in a hole with threaded sides. These threads can hold a decorative cap that hides the fixing bolt/nut, but their main function it to provide a purchase for the "crank puller", a special tool that is needed to remove the crank from the axle.
Counter steering
When a bicycle turns, it must lean into the direction of the turn so that the tilt of the bicycle and rider counterbalances the "centrifugal force" created by the act of turning.
In order to turn left, you start by turning the handlebars to the right for a moment. This moves the front wheel out to the right of the centre of gravity, so the bike will start to fall to the left. This is immediately followed by turning the handlebars to the left to cause the bike to remain in balance, which also creates the desired left turn. "Counter steering" refers to the momentary motion of the handlebars in the opposite direction of the desired turn.
Criterium
A criterium race consists of many laps around a short course. The course may be a few city blocks. Criteriums are good for spectators, less popular with racers.
A criterium bicycle will often have a somewhat higher bottom bracket than a road-racing bicycle, to allow pedalling through the turns (there are a lot of turns in a criterium!) Criterium bicycles are designed with a particular eye to manuverability, because the pelaton in a criterium is likely to be large and dense. Criterium bicycles are not usually built for comfort.
Cross Country
- Normal, pedal-powered off-road mountain-bike riding, as opposed to down hill racing.
- Riding across the whole width of a country (generally referring to the U.S.)
Cross Frame
A cross frame is basically made up of two intersecting members, forming a cross. The vertical member would be the seat tube, and, perpendicular to it would be a backbone, which might extend and split to form rear stays. This type of frame is not as naturally strong geometrically as the more common diamond frame, so it gets its strength from the use of large diameter tubing, or monocoque construction, particularly in the case of the back bone. There are often gussets or struts added to provide a measure of triangulation to the frame.
Cyclecomputer
An electronic speedometer/odometer for bicycles
Damping
Causing vibrations to stop, usually by the use of friction. In suspension systems, this is commonly done either by direct rubbing friction, or by pistons forcing fluids through small openings.
Derailleur
A mechanism for moving the chain from one sprocket to another to change gears on a multi-speed bicycle.
A typical derailleur consists of a parallelogram, which moves a cage. In the case of a rear derailleur, the cage will have two chain pulleys, a jockey pulley and a tension pulley. Different detailers have different capacities to handle different gear ranges. Also commonly spelled in the French style "Derailleur."
Dish
A bicycle wheel should have the rim centred directly in line with the frame. The fork ends are symmetrical with respect to the frame, and the hub axle locknuts (or equivalent surfaces) press against the insides of the dropouts.
Wheels should be built so that the rim is centred exactly between the axle ends on the hub. In the case of rear wheels, the spokes attach to flanges which are not symmetrical...the right flange is usually closer to the centreline than the left flange, to make room for the sprocket(s).
When rear wheels are built properly, the spokes on the right side are made tighter than those on the left side. This pulls the rim to the right, so that it is centred with respect to the axle (and to the frame.) Viewed edgewise, a rear wheel built this way resembles a dish, or bowl, since the left spokes form a broad cone, while the right spokes are nearly flat.
By extension, the term "dish" is used as a general synonym for accurate centring, even in the case of symmetrical wheels.
Disk Brake
A hub brake, similar to an automotive disk brake, consisting of a disk, which screws on to the hub and a calliper attached to the frame or fork, which squeezes on the disk. Disk brakes are better able to dissipate heat, which makes them popular for downhill events and for tandems.
Some early disk brakes had a reliability problem, in that outer part of the disk could break away from the part that attached to the hub. This would cause complete failure with no warning whatever. When the rider would squeeze the brake lever, it would feel solid, as the calliper was gripping the disk securely...unfortunately, it would do nothing to stop the bicycle!
Disk brakes are becoming increasingly common, partly because they work in wet conditions when rim brakes don't, partly because they don't cause wear to rims, and partly because of fashion.
Disc wheel
A disc wheel is a wheel with solid sides, instead of spokes. Although disc wheels are heavier than spoked wheels, they have less air resistance, and permit a cyclist to go noticeably faster. They are not usually used on the front, because they can cause severe handling problems in cross winds. They are not usually used for hilly conditions, because the added weight is too much of a disadvantage on the climbs.
Draft
To follow another cyclist (or motor vehicle) so closely that the leading vehicle takes the brunt of the wind resistance, and acts as a windbreak for the drafting cyclist.
Since air resistance is the major limitation on bicycle speed, most of the tactics used in bicycle racing are based on exploiting this effect.
Drive Train
The parts of a bicycle, which have to do with generating, forward motion. This would include the pedals, cranks, chainwheels, bottom bracket, chain, derailers, rear sprocket(s) and rear hub.
The drive train area of a frame would consist of those parts of the frame that are directly stressed by the drive train parts, specifically the chain stays, downtube, and seat tube.
Drop
- Frame geometry: the difference between the height of the fork ends and the height of the bottom bracket.
Smaller drop = a higher bottom bracket. This dimension is often preferred to the bottom-bracket height dimension, because it is the same whatever tires are installed on the bicycle.
A bicycle with a shorter drop (higher bottom bracket) will be less at risk of striking a pedal on the ground during high-speed cornering or obstacle jumping.
A bicycle with a longer drop (lower bottom bracket) will be slightly faster, and easier to mount/dismount.
- Handlebars: the vertical dimension of a drop handlebar, from the horizontal part to the level of the drops.
Drops
The lower parts of a drop handlebar, the area below the brake levers.
Drop Bolt
An offset mounting bolt, to allow a short-reach brake calliper to be used where a long-reach one would otherwise be required.
Drop Handlebar
A drop handlebar is one in which the middle of the bar is the highest point, or nearly. Most bicycles built for fast or long-distance riding have drop handlebars, which provide a range of different grip positions, allowing the rider to change positions for variety and to accommodate different road/wind conditions.
The most common style of drop handlebar is the "Maes" bend. Variations include the "randonneur" and "anatomic" bends.
Drop Out
A type of fork end that allows the rear wheel to be removed without derailing the chain first.
Track and BMX bicycles do not have rear dropouts, they use fork ends that open to the rear.
Rear dropouts come in two styles:
• Horizontal dropouts have a longish slot for the rear axle to fit into, which runs more-or-less horizontally along the dropout. They permit the wheel to be placed in various positions front to rear. Horizontal dropouts are necessary for bicycles which don't have derailers, because the axle must be moveable to adjust the chain tension.
With horizontal dropouts, it is possible to miss-align the wheel in the frame if it is installed carelessly. The axle nuts or quick-release must be tightened quite securely, or the chain tension may pull the axle askew.
• Vertical dropouts have a vertical notch for the axle to go up into, and the axle's position is not adjustable. With vertical dropouts, the axle cannot be pulled out of position, even if it is not properly secured.
Vertical dropouts require the use of derailleur gearing, and do not permit any adjustment of the position of the rear wheel.
On derailleur-equipped bicycles, the rear derailleur is attached to the right rear drop out, either directly to a hanger that is part of the drop out, or by way of an adaptor claw.
Dropout spacing varies among different styles of bicycles
Drum Brake
A drum brake is a hand-operated brake, which is built into, or attached to the hub of a wheel, with shoes that press against the inside of a cylindrical drum.
The drum may be the inside of an oversized hub shell, or may be a separate unit which screws on to the side of the hub, by threads like those to which freewheels attach
DT ®
Swiss DT is the leading manufacturer of spokes. When DT spokes first became available in the U.S. market in the late 1970's, they revolutionized wheel building. Although stainless spokes had been available previously, the quality of the threading on DT spokes and nipples was quite a lot better than that of brands that had previously been available. This allowed wheels to be built at considerably higher spoke tensions than had previously been possible.
Dual Suspension
Refers to a bicycle with suspension for both wheels.
Elastomer
An elas tic poly mer , a springy plastic used commonly as a spring or shock absorber, particularly in suspension forks and similar mechanisms.
An "elastomer fork" is a suspension fork, which uses elastomers as the active suspension element. Elastomers are also used in some suspension stems, seatposts and saddles.
Eyelet
• Reinforcement in a spoke hole of a rim. Eyelets provide a wider bearing surface against the rim, making it less likely for the nipple to pull through the rim. They also provide a smoother surface for the nipples to turn against while they are being tightened. Also sometimes called "ferrules".
• A braze-on or other threaded fitting for bolting an accessory to a frame. This term is mainly used to refer to the threaded tabs on fork ends, to which you may attach fenders or racks
Fatigue
Fatigue (metal fatigue) is the property that causes metal to break after repeatedly being bent past its yield point. This is a common cause of spoke breakage, and can also affect frames, handlebars and other parts.
A familiar example of metal fatigue is experienced if you open a pop-top beverage can then flex the top back and forth a few times.
Aluminium is more prone to metal fatigue than steel is, so aluminium parts have to be designed a bit stronger to make up for this characteristic
Ferrule
A metal or plastic fitting that slips over the end of a run of cable housing to provide a solid base for the end of the housing
Fixed Gear
A rear hub in which the sprocket is rigidly connected to the hub, without a freewheel.
Float
A property of a clipless pedal system that allows the rider to rotate the foot within limits, as opposed to a fixed cleat, which holds the shoe at a fixed angle in the yaw axis.
Pedals with float allow you to rotate your heel inward or outward to some extent before disengaging the cleat.
Fork
Usually refers to the front fork, the part of the frame set that holds the front wheel. The fork is attached to the main frame by the headset. The fork consists of the two blades that go down to hold the axle, the fork crown, and the steerer.
Frame
The skeleton of a bicycle. The most common type of frame is called the "diamond" frame, and consists of two (of three, depending on how you look at it) triangles.
• The front triangle consists of the seat tube, the top tube, and the down tube...well, it also includes the head tube, so it is not a perfect triangle, but the head tube is usually fairly short, so it is pretty close to being a triangle. The front triangle holds the saddle, the bottom bracket, and, via the headset, the front fork.
• The rear triangle (or triangles, if you count both sides separately) includes the seat tube, seat stays and chain stays.
The diamond frame has evolved over the course of more than a century, and every dimension has been tinkered with and fine tuned to the point that it is a nearly perfect design for the tubular materials commonly used.
This is not to say that it is the ultimate, however. For some applications the cross frame is still viable, and for mouldable materials, monocoque designs may yet eclipse the diamond. It is also not at all clear that the diamond design lends itself to suspension applications.
Frame Set
Usually, a "frame set" will consist of the frame and fork. In some cases, it may also include a headset and/or a seat post, or other parts peculiar to the frame involved.
Frame Size
Frame size generally refers to a measurement of the seat tube. This is measured from the centre of the bottom bracket to somewhere near the top of the seat tube. Unfortunately, manufacturers disagree about where to figure the top of the seat tube, so the same frame may have as many as 8 different size numbers attached to it, depending on the manufacturer!
• Frame size may be measured in inches or centimetres.
• Some manufacturers measure "centre-to-centre", i.e. to the intersection of the centre of the top tube with the seat tube.
• Some measure to the intersection of the top of the top tube.
• Some measure to the top of the seat tube (which protrudes a variable amount above the top tube.)
• Some measure, on bikes with a sloping top tube, to where the seat tube would end up if the top tube didn't slope!
• A further complication is that different bicycles have different-height bottom brackets, so the stand-over height of two different frames may differ, even though both are 58cm center-to-center!
If you ask a bike sales person "what size frame do I need", and get back a number as an answer, without specifying a particular make and model group, you are not getting good advice.
In my opinion, seat-tube length is not the most important frame dimension anyway.
Freeride
This is mainly a marketing term. Generally refers to off-road riding that is also off-trail. Freeride bikes are similar to downhill bikes, with long travel suspension, but are generally a bit lighter and are set up for climbing as well as descending.
Freestyle
Stunt riding, and the bicycles evolved for this purpose from BMX-style bikes. Freestyle bicycles resemble BMX machines, but are heavier, more rugged, and feature pegs, platforms and other places to stand. Freestyle riding is divided into "flatland" and "aerial" classes.
Freestyle bicycles usually are equipped with the "Potts modification" and a "rotor" which allow the handlebars and fork to be turned 'round and 'round at will without tangling the brake cables.
Freewheel
The mechanism that makes coasting possible. A ratchet mechanism that allows the rear sprocket(s) to drive the wheel when pedalled forward, but allows the wheel to turn forward independently even when the sprockets are not turning. In other words, the freewheel is the part which makes coasting possible.
Freewheels are normally sold with the sprockets attached, so this term is frequently used as a synonym for a cluster.
A standard freewheel attaches to a hub by screwing on to external threads that are part of the hub. The action of pedalling tightens the freewheel down on the threads, so no tools are required to install a freewheel.
To remove a freewheel requires a special tool, commonly called a "freewheel puller" or "freewheel extractor"
This tool is a splined unit that may be mounted in a vice or turned with a wrench. The splines engage matching splines in the interior (non-rotating) part of the freewheel body. Different brands of freewheels have used different spline patterns, but there is a recent tendency to standard on the Shimano pattern.
Older freewheels had simple notches and matching extractors with two or four "bosses" (prongs.) This obsolete system was prone to failure, and it is easy to ruin the tool and the freewheel while trying to remove the freewheel. When using a boss-type freewheel puller, the tool should be secured against the freewheel by tightening down the axle nut or quick release skewer.
Friction shifting
Shifting operated by a lever that moves smoothly through its range. With friction shifting, the rider must learn exactly how far to move the lever to get from one gear to another. If the rider moves the lever too far, or not far enough, the chain will not line up properly with the sprocket, causing noise and roughness
Gear
The "gear" of a bicycle relates to the mechanical advantage of the whole drive system. In a low gear, the pedals are easy to turn, but you have to spin very fast to get any speed up. In a high gear, the pedals are hard to turn, but you don't have to make them turn very fast to make the bicycle go fast.
The gear of a bicycle depends on the ratio between the sizes of the front and rear sprockets, and the size of the drive wheel. If the bicycle is equipped with planetary gears, they also affect the gear. There are several ways of designating gears numerically.
Grease
A lubricant in the form of a viscous paste, rather than liquid oil. Grease is generally a more difficult to apply, because most bicycle parts cannot be greased effectively without disassembly. Grease lubrication is commonly used on all ball bearings. Good mechanics also use grease (or oil) on the threads of most threaded fittings and fasteners, and also inside the steerer (to keep the stem from becoming stuck) and the seat tube (to keep the seatpost from becoming stuck.)
There are a great many different types of grease on the market with different special features, mainly for automotive applications. For bicycle use, almost any grease is adequate, since the loads and temperatures are generally low.
Group, Gruppo
A group is a set of parts for one bicycle from (usually) a single manufacturer. The practice of selling parts as a group (or "gruppo" in Italian) probably originated with Campagnolo in the 1960's.
A group would normally include (as a minimum) the following:
• Hubs
• Bottom bracket
• Derailers
• Shifters
• Brakes
If a particular manufacturer doesn't make one or more of these items, they may have some made under their name by another manufacturer to fill in their group. For instance, when Mavic was offering groups, they had everything above except for brakes, so they had brakes made under their name by Modolo and Dia Compe, and pedals by Look.
If the manufacture offers them, a group could also include:
• Pedals
• Headset
• Seat post
Note the distinction between a "group" and a "kit": In addition to the group, a kit includes everything needed to turn a frame into a bicycle: built-up wheels (rims, spokes, tires, rim tape, tubes), handlebars, saddle, etc.
The use of the Italian term "gruppo" is sometimes considered an elitist affectation, especially when referring to parts which are not of Italian manufacture. British cyclists sometimes use the redundant term "group set."
Gyro ®
A particular type of rotor, from Odyssey ®. The Gyro features a split cable, so that the rotor is pulled evenly from both sides. This avoids any mechanical friction from the rotor, since it does not slide along the stem shaft as with other rotors. In fact, the rotor part of the system touches nothing but the cables.
In addition, the Gyro has a ball-bearing built into it, so it has very little friction while turning.
Handlebar Tape
Cloth or plastic or leather tape that is wrapped around handlebars to provide better grip and some cushioning. Most commonly used on drop handlebars.
Sometimes incorrectly referred to as "handlebar ribbon." This mistake results from a translation error. (In French and Italian, there is no distinction between "ribbon" and "tape.")
Hanger
This term has several bicycle applications:
- A derailleur hanger is the part of a rear dropout to which the rear derailleur attaches. It is also another name for an adaptor claw.
- A cable hanger is a bolt-on cable stop used with centerpull or cantilever brakes. The front cable hanger is secured by the headset, the rear attaches to the seatpost bolt.
- A chain hanger is a small braze-on mounted on the inside of the right seat stay. When the rear wheel is not installed in the frame, the chain may be routed over this fitting to keep it from flopping around.
- "Hanger" is also an old-fashioned American synonym for "bottom bracket."
Hardtail
A motorcycle term for a bike which has no rear suspension. Some cyclists find this term offensive when applied to bicycles.
Headset
The bearing assembly that connects the front fork to the frame, and permits the fork to turn for steering and balancing.
A conventional threaded headset consists of four races plus associated parts:
• The crown race , which is pressed on to the bottom of the steerer, just above the crown.
• The lower head race is pressed into the bottom of the head tube.
• The upper head race is pressed into the top of the head tube.
• The adjustable race attaches to the steerer.
The adjustable race is secured by either a:
• Keyed washer and lock nut, for Threaded headsets or a:
• Star fangled nut and cap, or compression rings in the case of some threadless headsets.
Threaded vs Threadless
There are two different systems for attaching and adjusting the adjustable race:
• Traditional threaded headsets fit forks with threaded steerers. The adjustable race screws on to the steerer, and a locknut screws on after the adjustable race to secure it. There is normally a keyed washer between the adjustable race and the locknut for extra security.
• Threadless headsets have an adjustable race that slips over an un-threaded steerer. There are three distinct types of threadless headsets which adjust differently:
• "Aheadset" style threadless headsets, the most common type, require a threaded fastener, such as a Star Fangled Nut to be installed inside the steerer.
This type of headset must be used with a special handlebar stem that clamps on to the outside of the steerer, either with one or more binder bolts, or other means. The stem is further secured by a plastic or metal cap that is bolted to the star nut.
To adjust an "Aheadset"-type headset, the stem binder must be loosened, then the bolt that runs through the cap to the starnut is tightened, usually with a 5 mm Allen wrench. This presses the stem down against the tapered bushing that fits inside the adjustable cup. and takes up the slack in the system. The stem is then aligned with the front wheel and tightened with its binder bolts. (Once the stem binder bolts have been tightened, the adjusting bolt that goes to the star nut is under no significant stress, and may even be removed.)
• "Diatech" threadsets from Dia Compe use a special pair of collars, usually mounted just below the stem and above the top race. The lower collar has a bevelled, conical top surface, which fits inside of a matching bevel on the inner circumference of the upper collar.
The upper collar has a gap at one point, with a binder bolt to squeeze the gap together. (This upper collar may also include a cable stop for the front brake, if the bicycle has a rigid fork and conventional cantilever brakes.)
The handlebar stem is clamped tightly to the steerer, preventing the upper collar from moving upward. As the upper collar is compressed by the binder bolt it squeezes lower collar downward, taking up any slack in the headset bearings.
• The YST "GeForce" headset has a collar which slips over the steerer, and is clamped to it with a binder bolt near the top of the collar. The outside of this collar is threaded, and the upper bearing race screws onto these threads. The upper race assembly is fitted with a binder bolt that clamps it tight onto these threads when the desired adjustment has been attained.
The Ge Force is the only threadless headset which doesn't use the handlebar stem as part of the adjustment. These headsets may be used with any stem, either external clamping or internal expander/wedge type.
Headset sizing
The nominal size of a headset is based on the outside diameter of the steerer. This is a source of confusion , because the steerer is not visible on an assembled bicycle. In the case of a bicycle with a traditional expander/wedge type stem, the stem shaft will be 1/8" smaller than the steerer. Sometimes people measure the stem diameter and assume, incorrectly, that this is the size headset they have.
Head Tube
The front tube of the frame, through which the steerer passes. The length of the head tube gives a quick visual indication of frame size, because it varies more, proportionally, with frame size than any of the other tubes.
Housing
The outer sleeve through which a brake or gear cable is pulled. The housing transmits an equal push to counter the pull on the inner cable. Traditional housing consists of a tight spiral of steel wire, usually coated with plastic. Newer versions have synthetic liners to reduce friction. This type of housing is still used for brake cables
Housing stop
A fitting found at each end of a piece of cable housing. It consists of a socket to receive the housing, with a small hole at the bottom, which will let the inner cable slide through, but hold the housing end rigidly in place. This may be a braze-on, or may be part of a clamped-on part. An adjusting barrel is a type of housing stop.
Hub
The middle part of a wheel, to which the inside ends of the spokes attach. Consists of an axle, which attaches to the fork ends, a shell, to which the spokes attach, and bearings to connect the axle to the shell, permitting the shell to revolve around the axle. In the case of a rear hub, the shell would also have a provision for attaching the rear sprocket(s). Some hubs incorporate a coaster, drum, disk or roller brake. Some rear hubs also incorporate internal planetary gearing
Hybrid
A hybrid is a crossbreed, the result of taking features from two different sources and creating something different, with aspects of both. The term has two common uses in bicycle usage:
• Hybrid bicycles , also known as "cross" or "fitness" bicycles are a cross between a mountain bike and a touring bike. The best of them have the handlebars and control levers of a mountain bike, with the frame, gears, wheels and brakes of a touring bike.
Hybrids usually come with 622 mm (700c) wheels like road/touring bikes, but with wider tires than are normally supplied for touring. Most hybrid bicycles, unfortunately, come with tires that are designed for looks rather than for function. These are typically knobbies 35-40mm wide. These tires are not good for much. Knobby tires are good for dealing with soft sand and mud, but hybrid tires are too narrow for these conditions--if you plan on riding through soft sand and mud, you really should buy a mountain bike. When ridden on firm surfaces, these tires are noisy and slow, and can cause an irritating buzz as they roll. They also corner poorly on pavement.
Many hybrids, unfortunately, also take from the mountain bike side of the family, a high bottom bracket. High bottom brackets make sense for mountain bikes, which are intended for jumping over logs and threading through narrow single track. Since hybrid bikes are generally unsuited for this sort or riding, the awkwardness of mounting and dismounting with a high bottom bracket outweigh any possible advantage. This is particularly the case since hybrids are often used for urban cycling, where stop-and-go is the norm.
• Hybrid gearing is the use of both derailleur and internal gearing on the same bicycle. Hybrid gearing has traditionally been a do-it-yourself option for bicycle tinkerers.
Hybrid gearing is no longer limited to the do-it-yourselfer, since the Sachs 3x7 hub has become generally available. This is a 3-speed planetary-geared hub which is designed to accept a Shimano-type 7-speed cassette.
Hybrid gearing provides the close spacing with a wider range of gears than can normally be obtained with a simple derailleur system. It is also particularly well suited to bicycles with smaller than usual drive wheels, because the high range(s) of the internal gear eliminate the need for unusually large chainwheels to compensate for the small wheels.
Hydraulic
Operated by applying pressure to liquid in a tube. Some bicycles (and all automobiles) have hydraulic brakes, using liquid-filled tubing to connect the brake control lever to the calliper. Hydraulic brakes have less internal friction and are immune from cable stretch, but are expensive and harder to service than cable operated brakes.
Hyperglide (HG) ®
A system of ramps and special-shaped teeth on Shimano rear sprockets that permits much smoother shifting than older systems. HG sprockets are designed so that, as the chain moves from one sprocket to the next, it will engage the new sprocket before it has completely derailed from the old one. This makes for smooth, silent shifting.
Hyperglide requires that the teeth of adjacent sprockets be oriented specifically with respect to one another. It also reduces interchangeability to some extent. For example, a 17 tooth sprocket that is designed to be used next to a 16 tooth sprocket will be shaped differently from on designed to be next to a 15 tooth.
Indexed Shifting
Indexed shifting means that the shift control has positive detents or click stops that provide discrete positions corresponding to different gears. See friction shifting
Italian
Italian bicycles are built to specific standards of threading and dimension. Most parts on Italian dimension bicycles are interchangeable with British/ISO dimensioned parts.
The major exception is the bottom bracket. Italian bottom brackets are 70 mm wide, as opposed to the usual 68 mm dimension of British/ISO and French bottom brackets. The cup diameter is also larger. Sometimes, bicycles which have damaged bottom-bracket threads are machined out to Italian size to eliminate the damaged threads. Italian bottom brackets, like the French, use a right-hand thread on both sides, so the fixed cup is prone to loosening up unless very securely tightened.
Italian threading is a curious mixture of metric and British. Diameters are specified in millimetres, but threads are in threads-per-inch! In addition, the thread angle is 55 degrees, like the obsolete British Whitworth system, rather than 60 degrees as with U.S. and metric threads.
Italian freewheel and headset threads are the same as British/ISO, except for the thread angle difference. They may be interchanged, but you should not go back-and-forth between Italian and British/ISO headsets. Italian freewheels are basically extinct, so the issue is moot there. Italian size handlebars/stems generally use a clamping diameter of 26 mm. Many high-end aftermarket drop handlebars and "road" stems also use this size even if not Italian made.
ISO
The International Organization for Standardization. This is an international agency that is active in trying to rationalize bicycle design to make parts interchange more easily among bicycles made in different countries. Most ISO standards are compatible with British standards. These standards include:
• 1" x 24 tpi headset thread
• 1" (25.4 mm) handlebar/stem clamp diameter
• 1.375" x 24 tpi bottom bracket thread (left-hand on the fixed cup)
• 1.375" x 24 tpi freewheel thread
• 56 TPI spoke thread
• 1 mm axle thread
In the case of tires and rims, the ISO adopted the E.T.R.T.O. system, the modern system for designating tire and rim sizes. This is explained in detail in my article on Tire Sizing
Kevlar ®
A very strong artificial fibre, used in bulletproof vests and bicycle tires. Kevlar is used in tires two different ways, for two different purposes:
• Kevlar beads are used on some high performance tires. Replacing the normal wire bead with Kevlar ® saves about 50 grams per tire. Kevlar-bead tires have the additional advantage of being foldable, making them popular as emergency spare tires with touring cyclists. Kevlar-bead tires are somewhat harder to mount on a rim, and are more likely to blow off than wire-bead tires. They work best on "hook edge" rims.
• Kevlar-belted tires have a layer of kevlar under the tread surface, with the purpose of making the tire more resistant to punctures caused by small sharp objects, such as thorns and glass slivers. Kevlar-belted tires have slightly higher rolling resistance, price and weight than corresponding tires without the belt.
Keyed Washer
A keyed washer is a washer with a special-shaped hole that fits over a special shaft. It can slide, but not turn. The usual set up is to have a groove in the axle or shaft, and a washer's hole will have a small tang that fits into the groove. This is almost always used in headset and pedal bearings. It used to be common in hub bearings as well, but has fallen out of favour for that application.
Kickstand
A prop for holding a bicycle upright when it is parked. They are called kickstands because they are operated by the foot.
Knobbly
A tire with an "aggressive" tread pattern, that is, one with knobs or bumps of various shapes, designed to dig into soft surfaces for better traction. Knobby tires get better traction on soft surfaces such as mud, gravel, snow, and dirt, compared with smooth treaded tires.
Knobbly tires perform extremely badly on paved surfaces. The knobs greatly increase rolling resistance, and create annoying vibrations. They also corner badly on pavement, due to squirm.
Left (Hand) Thread
Most threaded fasteners are right threaded, so you turn them clockwise to tighten them. Some parts which are used in conjunction with rotating shafts would tend to unscrew themselves if they threaded normally, so they are threaded in the opposite direction. This is called a "left thread," "left hand thread" or "reverse thread."
Left-threaded fasteners are turned counter-clockwise to tighten them.
Left threads are found on left pedals, some bottom-bracket parts, and internal parts of freewheel.
Spoke nipples and the expander bolts that hold bar-con shifters in place often appear to have left threads, because they are approached from the opposite direction of most fasteners.
Limit Stop Screws
The limit stops are two screws that set the limits of how far the derailleur can move from left to right. They are usually located on the back of the parallelogram; sometimes they face outward to the bicycle's right. The ends of the screws bump into internal parts of the parallelogram when the derailleur has moved all the way in the direction controlled by that screw.
Lock Nut
A nut which is tightened against another nut to keep it from loosening up. Often, but not always, there will be a key washer between the lock nut and the cone or other part it secures.
Lock nuts are used to secure bearing adjustment of most hubs, headsets, pedals and sidepull brakes. Most hubs use lock nuts to secure the cones so that they will stay in adjustment. These lock nuts are the outermost parts which are screwed onto the axle, and their outer surfaces press against the insides of the fork ends of the frame. The lock nuts are therefore the reference point by which axle width and dishing are measured.
Lock Ring
A thin lock nut used to keep threaded assembly from coming unscrewed. Conventional bottom brackets use a lock ring on the adjustable cup to make it hold its adjustment.
• Hyperglide cassettes and freewheels use a splined lockring to hold the sprockets to the body.
• Fixed-gear hubs use a left (reverse) threaded lock ring to keep the sprocket from unscrewing when the cyclist resists the motion of the pedals.
Low (Gear)
A low gear is one in which the pedals move rapidly compared to the speed of the wheels.
Low gears are achieved by using small chainwheels and large rear sprockets.
Low gears are used for climbing hills, or for starting up from a stop.
Low-normal/High-normal
Modern derailers are spring loaded, pulled one way by the spring and the other way by the control cable. A "low-normal" derailleur is one in which the spring pulls it toward the lower gear(s). If you release the tension on the cable, it will shift to the lowest gear.
Up until the late 1950s, all spring-loaded detailers were low-normal type. When Campagnolo introduced the parallelogram-type rear derailleur, they changed to high-normal, and most rear detailers made since then have been of the high-normal type.
The major advantage of high-normal rear derailers is that, when used with a low-normal front, both levers move in the same direction for double shifts. This makes it easier to perform a double shift with down-tube shift levers.
The major advantage of low-normal derailers is that they generally downshift a bit better than high-normal units.
In the late 1990s, Shimano attempted to revive the low-normal rear derailleur design, using the trademark "RapidRise." This has met with limited acceptance.
Sun Tour used to make high-normal front derailers. The principal advantage of this was that the front and rear shift levers moved in the same direction to either raise or lower the gear, which was less confusing for beginner cyclists.
Lug
A lug is a socket that forms the junction between two or more frame tubes. Traditional bicycle construction uses steel tubes and lugs, joined together by brazing or silver soldering so that the space between the tube and the lug fills up with molten brass or silver alloy. Some aluminium or carbon fibre bicycles also use lugs, with glue instead of the brass or silver.
Some frames use internal lugs, with a necked-down section that fits inside of the tube, rather than having a socket that the tube fits into.
Lycra ®
A shiny, stretchy fabric, popular for cycling clothing. The stretchiness of Lycra allows it to snugly so that it doesn't flap in the breeze, while still allowing free motion of the legs.
Monocoque
A structure, such as a bicycle frame, built as a hollow shell, without an interior framework. The strength of a monocoque structure comes from the shell alone. Monocoque bicycle frames are uncommon, but have been made from carbon fibre and from formed sheet aluminium.
Mountain Bike
"Mountain bike" (MTB) is the currently preferred term for bicycles made for off-road use. Mountain bikes use 559 mm wheels, have at least 15 speeds, and usually have cantilever brakes. There was an attempt to make a copyright out of "MountainBike", but the term has become generic. Some have tried to promote the term "All Terrain Bike" (ATB) as an alternative, or to designate some subtle variant of the mountain bike, but this term has largely fallen into disuse.
Nipple
The nut that secures the end of a spoke to the rim of a bicycle wheel. Nipples have a normal right-hand thread, but because they are normally seen from the "bolt" side, it is often confusing which way to turn them. It is as if you were watching the hands of a clock move clockwise, but the clock was transparent, and you were looking from behind it.
One-piece Crank
A one-piece crank (OPC) consists of a single steel forging which constitutes the left crank, axle, and right crank in a single piece of steel. This type of crank set is found on older U.S. made bicycles, and many current low-end bicycles. It is also commonly used on BMX and freestyle bicycles.
Overshoes
Overshoes are simple covers that fit over your existing cycling shoes to protect the uppers and your ankles from the elements. There's a fair bit of variety when it comes to overshoes, some are a lot more waterproof than others.
- Materials
The most commonly used material is Neoprene, the same material that wetsuits are made from. It's stretchy, easy to fabricate and offers a lot of insulation. However, in spite of what many people think, it's not waterproof. It will shrug off road-borne grime, and will keep water out of your shoes over shorter journeys. Other materials you may find are nylon, Gore-Tex or similar, and fully waterproof layers of high tech materials like Teflon.
- Style
Most of the overshoes on test here are designed for road use, some for off-road, some for both. There are now a few more commuter-friendly overshoes hitting the market – like Ahu's knee-length Bike Boots – that will help you to keep the bottom of your trousers dry. These go further up your legs and can be totally waterproof – and they're a bit more cycle-friendly than trying to ride in a pair of green wellies…
- Sizing
As with so many items of cycling kit size really does matter. If your overshoes are too small, you'll have trouble getting them on and they'll wear quicker. Too large and the insulating properties are reduced. So where possible try before you buy.
• Closure systems
Velcro and zips are used for keeping overshoes on: Some use both. Velcro doesn't always work well in the wet or mud, but is more durable. Zips, while more secure can break – the zip jammed altogether on one of our pairs.
Oversized
Larger in diameter than the traditional sizes. This term is commonly used for headsets and frame tubing. Oversized parts are stiffer, and can be lighter for their weight if the walls are made thin enough. If the walls become too thin, however, they become too easy to damage by denting.
Pannier
A bag that hangs alongside one of the wheels of a bicycle. They usually come in pairs. Well-equipped touring cyclists often use two pairs, one on the rear, and the other on the front, for better weight distribution. If they are mounted so that the top of the pannier is below the top of the wheel, they are "low riders."
Pedal
The part you put your foot on. The axles of the pedals screw into the cranks.
Pedal Threading
Direction
The right pedal has a normal thread, but the left pedal has a left (reverse) thread.
The reason for this is not obvious: The force from bearing friction would, in fact, tend to unscrew pedals threaded in this manner. The fact is, however, that it is not the bearing friction that makes pedals unscrew themselves, but a phenomenon called "precession".
Pedal Types
• Plain pedals rely on the rider's coordination to keep the foot properly located on the pedal. This type of pedal is most popular with beginner or unsophisticated riders, who fear being unable to put a foot down in a hurry.
• Toe-clip able pedals (sometimes known as "rat trap" or "quill" pedals) which work with stirrup-like clips and adjustable straps to hold the foot in place. These were the near-universal choice of knowledgeable cyclists until the 1980's. Toe-clip pedals, especially "platform" pedals, may be used either with normal street shoes or with special cleated shoes. The use of cleated shoes with toe clips, however, was made obsolete by the development of:
• Clipless pedals , which provide a positive connection between the shoe and the pedal, without the constriction of straps.
Pinch Bolt
When a round part is held inside another round part, but adjustability is desired, the outer part will often have a slot or gap. This gap will be bridged by a bolt that can squeeze or "pinch" the outer part so that it will clamp onto the inner part. Such a bolt is called a pinch bolt. Most bicycles use pinch bolts to secure the seatpost into the seat tube of the frame, and to secure the handlebars to the stem. Threadless stems usually use pinch bolts to secure the stem to the steerer. Many tandems use pinch bolts to secure their eccentric bottom brackets.
The bolt may fit through "ears" that are attached to the outside of the outer part, or it may close the gap of a split collar which surrounds the upper part of the seat tube.
A few older bicycles used a collar and pinch bolt to secure a handlebar stem inside of the steerer. This system is particularly common on folding bicycles to allow the use of a quick-release for the handlebar stem. This required a compression slot to be cut into the steerer, which could constitute a stress riser.
Pinch Flat
A hole in an inner tube caused by getting the tube pinched between the rim and a hard, sharp object, such as a rock, curbstone or the edge of a pothole.
Pinch flats (also known as "snakebites" because there are usually two small holes in the tube, as if made by the fangs of a snake) are usually caused by carelessness or riding under-inflated tires. They can also be caused by the use of a tire which is too narrow for the weight it is asked to carry.
If the tire is too soft, or too narrow, it is easy for it to bottom out when striking an obstruction.
If the tire is hard enough and plump enough to carry the weight, the air will keep the tube from being pinched between the rim and the road hazard.
Presta
The narrow valve used on most high-performance bicycles, and all tubulars. Also known as a "French valve". The wider Schrader (automotive style) valve is used on children's bicycles and utility bicycles.
Presta valves have built-in valve caps, which must be opened before you can pump them up. These caps are "captive" nuts, which cannot be removed. Since there is no spring in a Presta valve, this knurled nut must be retightened after inflating the tire, or the valve may leak slowly.
Presta valves are light, and don't require as large a hole in the rim. Since the don't use a spring, they can be easier to pump with a hand pump.
Separate valve caps are not needed with Presta valves. Valve caps , lock rings and Schrader adaptors can actually be dangerous, if you ride tubular tires
There is a third type of valve, very rarely seen, which has a bottom similar to an Schrader and necks down to about the size of a Presta. This is a Woods valve, formerly popular in the British Isles and Asia. These low-tech valves work with rubber tubing and spit. This is also sometimes referred to as a "Dunlop" valve.
Quick-release Wheels
Quick Release wheels use a cam mechanism to allow the wheels to be removed quickly, and without any tools. This was invented in the 1920's by Tullio Campagnolo, when he suffered a flat while racing over the Croce d'Aune pass in the Italian Alps. His frozen fingers were unable to loosen the wing nuts used to hold his wheels in place.
When quick-release wheels started being supplied on bicycles intended for the general consumer market, ignorant users caused a rash of accidents due to front wheels falling off. The resulting lawsuits led to the addition of "lawyer lips" to most front forks, greatly reducing the convenience of quick release wheels.
Quick-release Brakes
To facilitate wheel changes, most high-performance road bicycles have a quick release mechanism that allows the brakes to be temporarily opened a bit wider than usual, so that the tire can fit through the brake pads.
Some brake quick releases are located in the brake levers, which is the best place for them. This type of quick release allows the brakes to work normally even if the user forgets to reset them after use.
Other quick-releases are located at the calliper or on the cable hanger. These must be manually reset after use, or the brakes may run out of travel. The better calliper-mounted QR's feature a cam which allows a variable setting. This is of use to racers who may knock a wheel out of true, because they can temporarily loosen the QR as much as it takes to get the bent wheel to clear the brake shoes.
Radial spoking
The oldest and simplest of spoke patterns. The spokes run straight outward from the hub to the rim. This is called "direct" or "radial" spoking. This pattern is not well suited for transmitting the torque of pedalling, or of a hub brake, but is suitable for front wheels.
Traditional cycling folklore holds that radial-spoked wheels give a "harsh" ride, due to the slightly shorter spokes they use. Jobst Brandt demolishes this fallacy nicely:
"...'radial spoking also gives you a very stiff wheel. You can actually feel increased bumpiness compared to a three- or four-cross wheel.'
"I think you are imagining all this. There is no change in radial elasticity between a radial and crossed spoke wheel with the same components, other than the length of the spokes. A 290mm spoke is 3% stiffer than a 300mm spoke of the same type. Since spokes stretch elastically about 0.1mm on a hard bump (not ordinary road ripples), the elastic difference between the radial and cross-three wheel is 3% x 0.1mm = 0.003mm. Copier paper is 0.075mm thick, and if you can feel that when you ride over it on a glassy smooth concrete surface, please let me know. You have greater sensitivity than the lady in "the princess and the pea" fable.
"If your story weren't so common, I would assume it to be a put-on, but it isn't. I find it amazing how humans love to believe unbelievable things, the more unbelievable the stronger the belief. It isn't new."
I would add that the deflection of the tire, the flex of the fork, stem and handlebars are each an order of magnitude greater than this theoretical deflection difference in the spokes. The difference in elasticity between spokes of different thicknesses is also much greater than the difference between spokes which differ in length by 3 %, but you don't hear the same complaints about wheels built with spokes of different thickness.
Rake
The "rake" or "offset" of a fork is the distance between the wheel axle and the extension of the steering axis. This may be accomplished by bending the fork blades, or by attaching the fork ends to the front of the blades, or by tilting the blades where they attach to the crown.
Rake is one of the three factors that affect the trail of the bicycle, which has a considerable influence on the handling qualities.
RapidFire ®
Shimano below-the-bar shift levers for upright handlebars. The original version of Rapidfire, introduced in the early '90's, had two thumb buttons, one above the other. One was for upshifting, the other for downshifting. Since the motion was the same for shifting in either direction, riders found it confusing, and it was quite unpopular.
The newer generation, known as "Rapidfire Plus" uses a thumb button to shift to a larger sprocket, and an index-finger trigger to shift to a smaller one. This is a great ergonomic improvement, and Rapidfire Plus has been widely accepted.
Rim
The outer metal hoop of a bicycle wheel. The rim does not include the spokes, or the hub.
Rollers
A treadmill-like device for riding a bicycle indoors. Consists of a framework with 3 rollers. The front wheel rests on top of one of the rollers, and the rear wheel sits between two of them. The front roller is connected to one of the rear rollers, so that as the rear wheel turns its rollers, the belt makes the front roller turn with them. This allows the bicycle to be "steered" within the length of the rollers, and allows the bicycle to be balanced as if it were being ridden on the road.
Compared with a stationary trainer, rollers have the advantage of forcing one to ride in a very smooth manner, and generally improve form and smoothness on the bike. For most riders, however, a stationary trainer allows a higher intensity of riding, since it requires no mental effort to stay balanced.
Mastering roller riding is tricky. It is helpful to start out with the rollers in a doorway, so that one can lean against the door frame to prevent a fall.
It is also useful to have a full-length mirror straight ahead, so that you can observe your form.
If you are having trouble learning to balance on rollers, make sure that you are looking straight ahead, not down at the rollers. It is much harder to balance if you look down.
It is also a very good idea to set up a fan to help cool you off, as the slipstream does when riding outdoors.
Roller Bearing
A bearing that uses cylindrical or conical rollers instead of balls. The major bicycle application of roller bearings is in some headsets. Roller bearing headsets are very long lasting, due to the greater contact surface area as opposed to ball bearings. Current units, however do not turn as freely as ball bearing headsets. This is due to the use of cylindrical rollers, rather than conical rollers. Cylindrical rollers do not naturally roll in a circle, but in a straight line.
Roller Brake ®
A Shimano trademark for a variant form of hand-operated drum brake. It uses a ring of rollers pushed outward by a cam to engage the brake shoe with the drum. The cam is operated by a cable from a hand lever.
Rolling Resistance
The friction caused by the flexing of the tire and tube as it deforms under load. For a given tire, rolling resistance will vary considerably with the inflation pressure: the higher the pressure, the lower the rolling resistance
Rotor
A mechanism used on freestyle bicycles to route the rear brake cable through a bearing assembly which surrounds the handlebar stem. This allows the handlebars and fork to revolve indefinitely without fouling the rear brake cable. See also Potts modification. Probably the best rotor currently available is the Odyssey Gyro ®
R.P.M.
R evolutions P er M inute, a measure of speed of rotation. In bicycling, this is most often used in discussions of pedalling cadence.
Saddle
Frequently called a "seat", a bicycle's saddle is not intended to support the rider's entire weight. Traditional saddles are made of leather stretched over a metal frame, hammock style. This type of saddle requires care and careful breaking in, but when this is done the classic leather saddle moulds itself to fit the particular anatomical shape of its rider.
Seat Pin
British term for seat post, particularly the simple "pipe" type seat post which uses a separate saddle clamp.
Seat Pillar
British term for seat post.
Seat Post
The tubular support that holds the saddle. The seat post telescopes into the seat tube of the frame, providing the adjustment for saddle height. It is usually secured by a pinch bolt at the top of the seat tube.
Older seat posts, and those on cheap bicycles, are basically pieces of pipe, perhaps with a different diameter (usually 7/8" / 22.2 mm) at the top end. A separate clamp attaches the saddle to this type of seatpost.
Modern, high-quality seat posts have the saddle clamp mechanism built into the top of the post. This type is also commonly referred to as "micro adjusting" because it permits a finer degree of adjustment of the saddle angle.
Seat posts come in a wide range of diameters, from 21.15 mm to 31.8 mm. Low end department-store bicycles are typically 21.15 mm (13/16"). Most bicycles with one-piece cranks, including most BMX machines use this size. Bicycles with standard-size (1 1/8" / 28.6 mm o.d.) seat tubes usually use sizes between 25.4 (1") and 27.2 (1.07"). They typically come in sizes with even-numbered tenths of millimetres (26.0, 26.2, 26.4...).
For standard-sized seat tubes, the larger the seat post the thinner the tube. Thus, a larger seat-post size is often an indicator of a lighter, fancier frame.
Seat-Post Bolt
The binder bolt that secures the seatpost in the frame. It may be a conventional bolt with a nut, or an Allen bolt, or a quick release.
Seat Stays
The thin frame tubes that run from the rear fork ends up to the seat cluster.
Seat Tube
The frame tube running from the bottom bracket up to the seat cluster.
Shimano
The leading Japanese manufacturer of bicycle parts. Shimano has come to dominate the industry, and to have a near monopoly on many parts categories. This gets them a lot of bad press, because they are perceived as the Goliath of the industry.
They achieved this position because they have the most successful research and development program in the industry.
Shorts
Good shorts are worth their weight in titanium. As with most things in life, you get what you pay for so it's not worth skimping at the till if you value comfort.
Good quality shorts tend to have more panels (sections that are sewn together) and a better quality padded insert. These are generally referred to as a chamois as that's what they used to be made from. However, for the sake of both hygiene and comfort, most modern inserts are synthetic and they often have antibacterial qualities. The pad's purpose is to provide extra saddle padding for comfort and to prevent nasty chafing. Be wary of awkwardly placed seams in the padding and shorts; any pad with a seam running along a point of contact with the saddle (eg down the centre of the insert) should be avoided.
Opinion is split when it comes to choosing between bib or non-bib shorts. We believe that bib shorts are by far and away the best option for comfort as shorts with an elasticated waist can slip or dig in on longer rides. On the other hand, lack of straps means non-bib shorts are slightly cooler.
Skewer
In a quick-release hub, the skewer is the shaft that runs through the middle of the hollow axle, and the associated hardware, in cluding the quick-release cam and the acorn nut.
A rod used to help maintain alignment in a stack of elastomer bumpers in an elastomer suspension fork.
Slick
"Slick" or "bald" tires, those with no tread pattern, or perhaps just a bit of siping, provide the best performance for bicycles which are used on pavement.
Slick tires are smooth and silent running, and have excellent traction. They have the lowest rolling resistance of all tire styles. Many people reject them because they look slippery, but in practice, they are not. Tread patterns on road tires are purely cosmetic, and have no practical value.
Spinning
· Pedalling at a rapid cadence in a lowish gear.
· A program of indoor exercising. "Spinning ®" uses stationary cycles, with a fixed gear and a heavy flywheel. A trainer guides a group of "cyclists" using loud music to regulate cadence.
In this specific context, but only in this context, "Spinning ®" is a registered trademark.
Spoke Patterns
Spoked wheels may be laced in several different patterns. Most wheels use the semi-tangent pattern, less common is "direct" or "radial" spoking. Some rear wheels are laced "half radial".
There are also "novelty" or fad lacing patterns, including the "crow's foot" and "snowflake" designs. These patterns are eye catching, but have no practical advantage.
Spoke Protector
A plastic or sheet-metal disk that fits between the cluster and the right-side spokes of a rear wheel. This is intended to prevent the derailleur from getting caught in the spokes, which can cause very extensive/expensive damage/destruction to the wheel, the derailleur, and the frame.
A spoke protector is not a necessity on a bike that is well treated, because the derailleur can't go into the spokes if it's properly adjusted and if it is not bent. Bicycles which are subjected to rough handling, however, are prone to getting the rear derailleur bashed in, and in such a case, the spoke protector can prevent very serious damage.
Stack Height
The stack height is the vertical space taken up by the headset. With a conventional threaded fork, the steerer tube is longer than the head tube by some amount. If a headset is chosen with a stack height greater than this difference, there may not be enough of the steerer free above the upper bearing race for the keyed washer and lock nut to be installed. In the case of threadless headsets, the stack height also includes the height of the part of the handlebar stem that clamps to the steerer.
Stainless Steel
A family of steel alloys, usually containing 10-20% chromium, among other alloying elements. Stainless steel is rust resistant, and very tough, but is generally not the best choice in applications where surface hardness is of primary importance, such as bearings.
The primary bicycle application for stainless steel is for spokes. Virtually all modern high-quality spoked wheels are built from stainless steel spokes.
Stainless steel is also used for high quality control cables.
Standover Height
One of the prime dimensions of a bicycle, this refers to the height of the top tube above the ground. If the standover height is too tall for a given rider, mounting and dismounting will be awkward and dangerous.
Conventional wisdom is that the standover height should permit 1-3 inches (2-8 cm) of clearance between the top tube and the crotch of a rider straddling the frame, for road use. For off-road riding, considerably more clearance is required
Stem
The part that connects the handlebars to the steerer of the fork.
Types of stems:
• Conventional stems for most bicycles with threaded headsets fit inside the steerer of the fork, and use an expander/wedge to attach to the steerer. The stem diameter must match the inside diameter of the steerer, which is usually 1/8" smaller than the nominal headset size.
• "Threadless" type stems clamp on to the outside of the steerer, so they must match the outside diameter of the steerer, which is the same as the nominal headset size.
• Stoker stems for tandems are very similar to "threadless" type stems, except that they clamp on to the seat tube of the rider in front, rather than to a steerer.
• Pinch-bolt type stems are not in common use any more. They work with a fork that has a steerer with a slot cut into it, and a collar with a pinch bolt or quick release. These are most often seen on folding bicycles, because this design permits the use of a quick release.
• "Adjustable" stems, (also known as "Major Taylor outriggers", after their inventor), have the handlebar clamp unit mounted on a moveable part, permitting setting different amounts of forward extension.
Straight gauge
Not butted, i.e., a tube which has the same wall thickness from end to end, or a spoke which has the same thickness from end to end.
Tire Lever
A special tool for prying the bead of a tire over the rim. Most tire levers have a rounded end which slips between the rim wall and the tire. The other end of the lever is bent and has a notch. Once you have inserted the first tire lever and pried one section of the bead over the edge of the rim, you can hook the other end around a spoke. This leaves your hands free to stick another lever in, usually two spokes over from the first.
One or two tire irons are usually enough to get all but the most recalcitrant tire beads over the rim, but in extreme cases you may need three. When the third is in place, the middle one can be removed and re-inserted farther over. This is why they are usually sold in sets of three, since you never need more than three.
Since most new tire levers are made of plastic, the term "tire iron" is a bit anachronistic.
Toe In
When a brake shoe hits a moving rim, the pull of the rim causes the brake arm to flex a bit. If your brake shoes hit a stationary rim perfectly straight and squarely, the flex of the brake arm will cause the rear edge of the brake shoe to do the brunt of the work. The front edge of the shoe may not even be engaging the rim under hard braking.
Good practice in installing brake shoes is to "toe them in", so that the front part of the shoe hits the rim first. As the brake arm flexes under real braking, it will permit the whole surface of the brake shoe to engage the rim.
Toeing in of brake shoes can also reduce the annoying squeal some brakes make when in use.
Most new brake shoes have special washers with curved surfaces to allow you to adjust the angle of the shoe to the rim. Older brakes relied on brute force, typically bending the brake arm with an adjustable wrench.
Top Pull
A style of front derailleur operated by a cable coming down from above, as opposed to a traditional "bottom-pull" unit, operated by a cable coming up from below. Top pull detailers are mainly used on mountain bikes, because they permit the designer to avoid running the gear cables by the bottom bracket, where they are exposed to spray from the front wheel.
Top-Swing ®
Most front detailers use a parallelogram which is fixed (attached to the derailleur body) at the top, with the moveable cage attached to the bottom link of the parallelogram. Many of the newer Shimano units are built "upside down": the bottom of the parallelogram is fixed in place and the cage attaches to the top link.
A peculiarity of Top-Swing ® derailers is that the limit stop adjustment screws are reversed, so that the outer screw limits inward travel, and vice versa.
Top-Swing ® derailers clamp on to the seat tube lower down than bottom-swing units. (Some don't even attach to the seat tube, but are held on by the bottom bracket mounting ring.) Some frames made for use with top-swing derailers will not permit the installation of conventional bottom-swing derailers, because there's a bottle braze on in the way. Some suspension frames also require a top-swing front derailer for clearance reasons.
Top-Swing ® or bottom-swing derailers can be (and are) made in either top-pull or bottom-pull versions. (This has to do with the direction from which the cable approaches.)
Top Tube
The frame tube that runs horizontally from the top of the head tube to the seat cluster. Up until the 1980's, most high quality bicycles were built with the top tube exactly horizontal. Newer frame designs commonly have sloping top tubes, higher at the front. This is particularly common in smaller frame sizes.
The length of the top tube is probably the most important dimension in providing a comfortable fit. See my article on Frame Sizing.
Torsion, Torque
A force applied in the form of a twist, rather than a straight push or pull. "Torsion" is used to indicate that the force involved it a rotary force. "Torque" is a measurement of torsional force.
Torque is the linear force times the radius at which it is applied. For example, a 10 pound force applied two feet from the axis produces the same torque as a 2 pound force applied ten feet from the axis.
The standard units for measuring torque are pound-feet or Newton-meters. Note that the force unit goes first, so as not to be confused with energy/work measurements. A common error is to refer to "foot-pounds" instead of pound-feet of torque. This is not strictly correct, since the foot-pound is a unit of energy/work, not torque.
Torque Wrench
A "torque wrench" is a type of wrench with a built-in spring-loaded indicator that gives a numerical readout of the amount of torque being applied through it.
This is primarily an automotive tool, especially useful for applications involving crushable gaskets which must be tightened evenly.
Torque wrenches are never needed for bicycle work, although they can be a useful training aid for inexperienced mechanics that haven't learned the feel of a properly-tightened fastener.
Track Mitts
British term for fingerless cycling gloves.
Track Nut
An axle nut with a built-in washer loosely riveted to it. The washer is permanently attached, but can rotate with respect to the nut. Used on high quality solid-axle hubs. Cheaper solid-axle hubs use serrated flange nuts, or plain nuts with serrated washers.
Traction
The frictional force that keeps a tire from skidding. A tire with good traction will be less likely to skid.
The traction of a tire is affected by:
• The composition of the rubber of the tire
softer rubber gives better traction, but wears out sooner.
• The nature of the road or other surface
Paved or unpaved, wet or dry, hard or soft, smooth or bumpy.
• The tire pressure
• If the tire is too soft, it can "squirm" and deform itself so that it will not track properly when making turns.
• If the tire is too hard, it will bounce excessively on rough surfaces, bounding from bump to bump, spending too much time airborne.
• The shape and depth of the tire tread.
This is mainly a concern in the case of tires for off-road use, where a knobbly tire can get a bite of a soft or irregular surface.
For pavement riding, smooth tires get as good traction as those with tread, sometimes better. Aggressive knobbly tread tires corner very poorly on pavement, because the tall knobs bend sideways under stress.
Trail
Trail is the distance from the contact point of the front wheel with the riding surface to the intersection of the steering axis (head tube) with the surface. The trail is a function of the head angle, the fork rake, and the tire diameter. Trail has a major effect on the handling of a bicycle. More trail increases the bicycle's tendency to steer straight ahead. A bicycle with a largish trail dimension will be very stable, and easy to ride "no hands". A bicycle with a smaller trail dimension will be more manuverable and responsive.
Tread
- The contoured surface of a tire, used to improve traction in loose or rough surfaces. Knobbly or grooved tread designs have no real value for use on paved surfaces, and extreme tread patterns increase drag, noise and reduce cornering traction due to squirm. Despite appearances, slick tires perform best on hard surfaces.
- The lateral distance between the pedal attachment points on a crankset. For most cyclists, the narrower the tread the better. When we walk, our footprints fall almost in a straight line under the centre-of-gravity of our bodies. When we cycle, the "tread" forces our feet to be exerting their force farther apart than they are designed to do. Some theorists blame this for knee and hip problems experienced by some cyclists, but the jury is still out on this.
A wider "tread" also creates a greater sideways force when pedalling out of the saddle, so the rider must exert more upper-body strength when riding "en danceuse".
A wider "tread" decreases pedal-ground clearance when the bicycle is banked over into a tight turn.
Trekking Bicycle
This seems to me to be basically a bit of marketing hype. "Trekking" bikes are basically indistinguishable from 700c "hybrids" except that they come with a lot of accessories that are not stock on a hybrid, such as fenders, racks and generator lighting systems.
Another way of looking at it is that a trekking bike (or a hybrid for that matter) is basically a touring bike with upright handlebars instead of drops.
Although the word "trek" is of Afrikaans origin, meaning a long painful journey on foot or by oxcart, I believe the term "trekking" bike originated in Germany in the 1980s.
Trials
A form of bicycle acrobatics, in which the object is to navigate a course that is as close to un-rideable as possible, without putting a foot down (known as "dabbing.")
Trials are sometimes done on more-or-less standard mountain bikes, but more often with purpose-built trials bikes.
A trials bike is a one speed, geared very low, with a tiny chainwheel both for low gearing and improved clearance. Tires are usually fat 20" or 24" size, with aggressive tread. Frames are small, equipped with a very low saddle. Trials riders never actually sit on the saddle, but a saddle is required as a safety measure.
The major technique involves locking the wheels up with the brakes, and bouncing the bike up and down in the manner of a pogo stick.
Triple
A crankset with three chainrings. The smallest, inner chainring is commonly referred to as a "granny gear."
This term is sometimes used incorrectly to refer to a triplet, a 3-place tandem.
Triple Butted
Double butted, but with different thickness butts on each end.
This term may apply to frame tubing or to spokes.
True, truing
A "true" wheel is one in which the rim is perfectly concentric and runs along a plane perpendicular to the axle.
A wheel which is "out of true" vertically will be out of round, and will give a bumpy ride even on a smooth road.
A wheel which is "out of true" horizontally may rub on the brake shoes at part of its revolution, causing excessive drag...or causing the brake to be adjusted looser than it should be to prevent this drag.
Tube (inner)
Inside of all modern bicycle tires you will find an inner tube, which is basically a rubber balloon with a valve that fits through the rim so that you can inflate it.
The purpose of the tube is to make the tire airtight. The tire itself may have small holes and pores without creating a problem, as long as the tube doesn't leak. If the tire has a large hole or cut, the stretchy rubber tube can bulge through and burst. The tube does not, in itself, have the ability to withstand the high pressures used in bicycle tires without the support of a tire around it.
Most tubes are made of synthetic (butyl) rubber.
Tubing (frame)
Traditional bicycle frames are built out of metal tubing, generally aluminium, steel, carbon fibre or titanium.
Tubular
A type of tire mainly used for racing. A tubular tire has no beads; instead, the two edges of the carcass are sewn together (hence the term "sew-up") with the inner tube inside. Tubulars fit only on special rims, where they are held on by cement.
Tubulars use Presta valves. You should never use valve caps or other screwed-on valve accessories with tubulars.
For most non-competitive applications, conventional clincher tires are more appropriate.
Most people find expensive tubulars too expensive for recreational riding...but cheap tubulars are distinctly inferior to good clinchers, particularly in that they tend to be lumpy and crooked.
Comparing high-quality tubulars with clinchers, including the rims, tubes, etc, tubulars save about 50 grams per wheel...but your bike winds up heavier, because you really need to carry a complete spare tubular, as opposed to a tube and/or a patch kit. This doesn't apply if the team car is carrying spare wheels/bikes for you.
If you don't glue your tubulars on properly, they can roll off, causing you to crash. If you get a flat on the road, you can't glue your spare securely, since the glue needs to dry overnight; as a result, you have to ride very gingerly on your spare, taking it really easy on the curves and descents. If you get two flats on the same ride, you're screwed.
Some people believe that tubulars corner better in the rain...but I never go fast on wet roads anyway. If you flat in the rain, your ride is over, because there's no way to make a wet tubular stick to a wet rim.
Tubulars are fairly immune to "snake-bite" rim cuts, and may offer slightly better "suspension" action than comparable clinchers. Their rolling resistance is actually worse than good clinchers in most cases, due to flex of the glued section.
Valve Cap
A metal or plastic screw-on cover intended to protect the innards of a tire valve from dust and other foreign matter.
In the case of Presta valves, which have non-removable, built-in caps, external caps are unnecessary in use. The purpose of these redundant caps that come with Presta tubes and tubulars is so that the pointy end of the valve won't puncture your spare tube or tubular while it is rolled up.
These caps are actually dangerous if you ride tubular (sew-up) tires: Should your tubular come unglued and roll off of the rim, with luck, you will be able to roll to a semi-controlled stop on the bare rim. If you have a cap (or Schrader adaptor) screwed onto the valve, the wheel will only roll until the captive tubular bumps up against the frame or fork, then the wheel will lock up, and down you will go!
V-Brake ®
A Shimano trademark for a direct-pull cantilever brake. This is a cantilever which does not use a separate transverse cable. It has two tall arms, one of which has a housing stop and the other an anchor bolt. The exposed part of the cable runs horizontally from one arm to the other.
V-Brakes and other direct-pull cantilevers have more mechanical advantage than other brakes, so they require special hand levers with less-than-average mechanical advantage to keep the overall mechanical advantage in a useful range.
Some V-Brakes also incorporate a parallelogram linkage that maintains the shoe at the correct angle as it approaches the rim. This feature also allows the motion of the shoe to be more nearly horizontal than conventional cantilevers.
"V-Brake" is a Shimano trademark.
Wedge bolt
Conventional handlebar stems use a long bolt running down the middle of the shaft to clamp the stem to the inside of the steerer. At the bottom of the stem shaft this bolt screws into a special shaped nut. These nuts are of two different types:
• Wedge-type stems have the bottom of the shaft cut off at an angle, and the nut is cylindrical with an angled top surface to match the angle of the bottom of the stem shaft. As the bolt is tightened, the wedge-shaped nut is pulled sideways so that it presses against one side of the steerer, and the shaft presses against the other side of the steerer. Most new stems are of this type.
• Expander-type stems have square-cut shaft bottoms, but have one or two slots cut up from the bottom of the shaft. The nut is in the shape of a truncated cone. As the bolt is tightened, the conical nut spreads the bottom edge of the stem shaft outward, pressing it against the inside of the steerer.
Each system has advantages and disadvantages:
• Wedge-type stems:
• Provide a more positive lock against the steerer (which may be an advantage or a disadvantage...if the stem is too tight there is a greater risk of bending the handlebars in a crash.)
• Are easier to adjust. In most cases, just loosening the wedge bolt will permit the bars to be raised, lowered or straightened.
• Are cheaper to manufacture.
• Expander-type stems:
• Are less likely to damage the steerer if over tightened.
• Do not require quite as deep an insertion into the steerer.
• Are harder to adjust, because it is usually necessary to knock the wedge loose by striking it with a mallet after loosening up the bolt.
Wishbone
Wishbone type frames have seat stays that do not run all the way up to the seat cluster. Instead, there is a single tube running from the seat cluster down to where the brake bridge would normally be. The seat stays come up and join this tube, much as the blades of a unicrown fork join the steerer. The advantage usually given for this type of construction is that it provides a more solid mounting for cantilever brake studs, since there is only a short length of narrow seat stay above the stud.
Wrench
A tool for turning nuts or bolts. This term is not common in British usage, where the term "spanner" or "key" is generally preferred.
Wrenches are divided into two families:
· Fixed Wrenches are made of a single piece of metal, and only fit specific sizes of fasteners. Fixed wrenches are made for different sizing systems, including Metric, S.A.E., and Whitworth. Types of fixed wrenches include:
• Box Wrenches have a complete loop that surrounds the fastener. They are substantially stronger than
· open-end wrenches, and are the best use for high torque applications, both because the wrench is stronger, and because it can contact more than two corners of the fastener.
• Combination Wrenches are double-ended wrenches with an open end and a box end, usually for the same size on each end. This is the most useful and most common general-purpose wrench style.
• Open-end Wrenches have ends shaped like a two-tined fork. They normally have two parallel surfaces that bear against two of the sides of a fastener. Open-end wrenches are faster to put on to fasteners, and are the only kind that can be used where there is not clearance to slip a box wrench over the end of the fastener. (Cone wrenches, headset wrenches, pedal wrenches and spoke wrenches)
Bicycle applications often call for special-purpose open-end wrenches:
• Cone wrenches and headset wrenches differ from normal open-end wrenches in that they are thinner than usual for a given fastener size.
I have an article about Cone Wrenches in my Tool Tips series.
• Pedal wrenches are thin open-end wrenches with heavy-duty jaws and extra-long handles.
• Spoke wrenches have taller contact areas than most wrenches and have short handles for use in the close quarters between spokes.
• Socket Wrenches, similar to box wrenches, surround the fastener. Unlike box wrenches, the outside of the head of a socket wrench is circular so that it can reach a fastener that is recessed into a hole. A socket wrench may have an offset handle, as with a peanut-butter wrench, but more often, the handle will attach to one end of the socket.
Most socket wrenches are part of modular systems, and have interchangeable handles available, including ratchet handles, torque-wrench handles, extensions, breaker bars, and screwdriver-type handles.
6 Point vs. 12 Point Socket and box wrenches for hex fasteners come in two types, 6 point and 12 point.
12 point is good for box wrenches, because it gives you twice as many possible orientations to put the wrench on the fastener. This is especially good for working in close quarters, but is rarely an issue on bicycles. 6-point wrenches are stronger and less likely to slip. Generally, 6 point would be preferable for bicycle work when you have a choice.
• Nutdrivers are smaller sized socket wrenches with screwdriver type handles. These are often faster to use than conventional wrenches, and the screwdriver-type handle makes it unlikely that you'll strip the threads of a smaller nut or both. 8 mm, 9 mm and 10 mm nutdrivers are among my favourite bike tools. They usually have a hollow handle so they can even be used to run a nut down a long bolt.
• Spanner Wrenches use pins to engage holes or notches in the fastener.
• Pin spanners usually use two pins that fit into a pair of holes in the surface of a fastener. Common bicycle applications for pin spanners include adjustable bottom-bracket cups and freewheel bearing cones. Some crank dust caps and headset lock nuts also use pin spanners.
• Hook spanners have an end shaped a bit like a capital "G". They wrap around a round fastener and the tail of the "G" fits into one of several notches on the fastener. Hook spanners are commonly used on bottom-bracket lockrings and track hub lockrings. They are also used on some headsets.
• Allen Wrenches are hexagonal wrenches that fit into the matching hexagonal holes of Allen bolts.
• Spline Wrenches (including Torx, freewheel, etc.)
· Adjustable Wrenches can be adjusted to fit different sized fasteners, usually by the use of a thumbscrew. They don't fit as well as the correct size fixed wrench, so good, well-equipped mechanics only use them as a last resort.
• Crescent ® Type Wrenches. Although "Crescent" is a trademark, it is commonly used in the U.S. to refer to a normal, angled head adjustable wrench regardless of brand. The jaws are set at a 30-degree angle to the handle to allow them to be used in tight quarters.
• Monkey Wrenches have their jaws perpendicular to the handle. They commonly open up much wider than crescent-type wrenches.
• Pipe Wrenches are similar to monkey wrenches, except that they have serrated jaws, which are designed with a bit of play which causes them to grip more tightly when turned in the appropriate direction. Pipe wrenches are primarily used for plumbing, generally have no bicycle application.
• Adjustable pin spanners fit a range of different pin spacing. The spring-loaded Park SPA-1 (green) adjustable pinwrench is the most useful one for most adjustable bottom-bracket cups.
Wrenches are sometimes confused with pliers, and naive users sometimes try to use pliers for jobs that really require a wrench. This usually results in damage to the nut or bolt so abused. It can also cause failure due to under tightening the part involved.
