As time went on, the Bicycle Glossary has grown, and many of the pages became inconveniently large.
I have split the larger pages into smaller ones, but I realize that there may be external links pointing to the older pages. For this reason, I have maintained copies of the older pages at the same location.
This is one of the older pages, and the newer pages that were derived from it are liable to be more complete and up to date, so please follow the links below to the current version. Sorry for any inconvenience.
If one of my own pages had a link that took you to this page, it would be helpful if you would send me an email with the URL of the page that had the bad link, so I can update it.
Sheldon Brown
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- A speed competition. Bicycle races take several forms:
- Bicycle Motocross (BMX) races.
- Cyclocross races.
- Mountain bike races. (Downhill and Cross-Country)
- Road races.
- Track races.
Races in any of these categories may take the form of mass-start events or time trials.
- The part of a ball-bearing or roller-bearing assembly on which the balls or rollers roll.
In the case of conventional bicycle bearings, the races take the form of a cup and matching cone.
The races in cartridge bearings there is an inner and an outer race, both in the same plane as the balls.
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- An accessory framework which attaches to a bicycle for carrying baggage, often used with panniers or other bags.
- A device which attaches to an automobile to carry bicycles. Car people call these "bike racks"; bicycle people call them "car racks".
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- 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 pedaling, 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 290 mm spoke is 3%
stiffer than a 300 mm 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 = 0.003 mm. Copier paper is 0.075 mm 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.
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- 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.
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- The Raleigh bicycle company of Nottingham, England, was, for many years the largest cycle factory in the world. Over the first two-thirds of the century, Raleigh absorbed most of the independent bicycle manufacturers in Britain.
Raleigh had its own standards for threading and other dimensions, which were different from standard British dimensions. In particular, they used 26 threads/inch, rather than 24 for headsets and bottom brackets. More information on older Raleighs is available in my article on English 3-speeds, and my Raleigh Sports Page.
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- The rim style used on higher end Raleigh 3-speeds. The Raleigh pattern rim was similar to the Westwood rim, except that it had flat sides and square corners, so it could be used either with caliper brakes or rod brakes. It may have been the strongest rim ever made. This style of rim is most commonly found in the 590 mm (26 x 1 3/8) size and smaller.
Raleigh pattern rims are sometimes also referred to as "Westrick", which is a made-up word combining "Westwood" with "Endrick." Westwood rims were only for use with rod brakes; Endrick rims were only for use with caliper brakes, but Raleigh Pattern, a.k.a. "Westrick" rims can be used with either type.
They combine the raised (or dropped, depending how you look at it) center that keeps rod brake shoes free from the risk of hitting the spokes, with the flat sides required for rim brakes.
Raleigh Pattern rims are preternaturally strong, probably the strongest bicycle rims ever made.
There is also a Schwinn copy of this design, seen on some older Schwinn 3-speeds. The Schwinn used the larger 597 mm bead seat, instead of the 590 used on most English 3-speeds.
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- The French word "randonnée" is not exactly translatable into English. The closest is probably "hike", which is not commonly used in bicycle contexts. A randonné is an organized group ride, with some emphasis on speed, but it is not a race. Riders will typically be on road-racing or light-touring bicycles. Randonnées are often quite long, but do not normally involve stopping for the night away from the start. Some randonnées run all night. One of the most famous (and most rigorous) is the quadrennial Paris-Brest-Paris ride, 1200 kilometers, (750 miles) stopping only for meals and catnaps.
To be eligible to ride in major randonnées, a rider must qualify by riding a series of shorter randonnées called "brevets."
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- A cyclist who participates in randonnées.
| A type of drop handlebar, similar to the Mæs bend, except for an upward sweep on either side of the stem, which provide a somewhat more upright riding position.
This type of handlear was formerly very popular on French touring bicycles, but has fallen out of fashion.
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- 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.
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- Shimano's trademark for low-normal rear derailers.
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- A mechanism which will rotate freely ("freewheel")in one direction, but either will not turn the other way, or will drive some other part when turned the other way.
A bicycle's freewheel has a ratchet which causes the sprocket to turn the wheel forward when the rider pedals forward, but allowing the wheel to turn forward even when the pedals are not being turned.
Ratchet wrenches turn a nut or bolt only when moved in one direction, leaving the nut or bolt in place when turned the other way. This allows the wrench to be used by swinging it back and forth, without having to lift it off the nut or bolt for the backswing.
A ratchet was also part of the Sun Tour Power Ratchet shift levers.
Most ratchets use spring-loaded pawls to engaged a toothed ring for forward drive, while the teeth in the ring slide over the ends of the pawls when freewheeling.
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- Old colloquial term for toe clips. Also, a type of pedal designed to accommodate toe clips.
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- The extension of a handlebar stem.
- The distance forward from the horizontal part of a drop handlebar to the drops.
- The effective length of the arms of a caliper brake. This is measured from the centerline of the center bolt perpendicularly down to the middle of the brake shoe. Reach is commonly expressed as a range (allowing for the fact that the brake shoes are adjustable, typically over a 10-15 mm range.)
Reach dimensions can run anyhere from 39-108 mm. There has been a historical trend toward shorter reach brakes, as newer bicycles, particularly racing-style road bikes, are designed for use with narrow tires and without clearance for fenders.
The reach required for a particular installation depends on the frame construction (how low the brake mounting holes are) and the rim diameter.
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| This caliper has a reach range of 39-49 mm. As shown, with the brake shoe adjusted all the way up, it measures 39 mm from the center of the bolt to the center of the brake pad. | This fork and rim combination call for a brake caliper that can be adjusted to provide a 45 mm reach. The caliper shown would fit. |
Some people refer to "short reach" "normal reach" and "long reach" calipers, but this is a recipe for confusion. As fashion has changed, the 47-57 mm size that used to be "normal" has become "long" and the longer-reach calipers have become nearly extinct. Currently, "short reach" calipers usually offer a range of 39-49 mm. This has become the de-facto standard for "road" calipers, and can now be considered "normal", though it is also correct to call it "short."
If you wish to avoid confusion, use numbers, not the ambiguous "short/medium/long" designations, and especially, don't refer to "normal" reach calipers.
If you need a brake with longer reach, you can effectively extend the reach by using a drop bolt.
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- The arm which connects a Hub brake to the chain stay or fork blade. It is designed to prevent the axle and other non-rotating parts of the hub from turning under the stress of braking. The reaction arm may be attached to the stay or fork blade either by a metal strap, or by a braze-on. The "Pacman" braze-on allows the wheel to be removed without having to un-bolt the reaction arm from the frame.
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- A cutesy term for the stoker of a two-person tandem.
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- The distance from the bottom bracket to the rear axle.
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- Caliper brakes have a center bolt 6 mm or 1/4" in diameter, which fits through matching holes in the fork crown and the brake bridge of the frame. Traditionally, these bolts have been long enough to protrude all the way through, to be secured by a normal hex nut, and associated washers.
Most newer good-quality bicycles that use caliper brakes use recessed mounting to save weight and for a more elegant appearance. Calipers intended for recessed mounting have much shorter center bolts, which do not extend all the way through the crown/bridge. Frames/forks designed for recessed mounting have stepped holes...6 mm in front, substantially larger at the back. Instead of a conventional hex nut that takes a 10 mm wrench, a cylindrical nut is used, which is broached for a 5 mm allen wrench.
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Recessed Mount Rear Caliper
Uses 5 mm Allen Wrencn | Traditional Nutted Rear Caliper
with 2 radiussed washersUses 10 mm wrench |
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Because the trend toward recessed mounting and toward short reach calipers happened simultaneously, most short-reach calipers come set up for recessed mounting. Medium- and long-reach calipers usually come with longer centerbolts for conventional mounting.
Mounting recessed calipers on older frames
Rear: Front calipers for recessed mounting have bolts that are long enough to mount in back, if you substitute the appropriate washers and a 6 mm nut.
Front: Here are 3 options:
- Drill out the back of the fork crown (8 mm or 5/16 drill bit). This is actually quite easy to do with a handheld electric drill, since you're only enlarging an existing hole.
That's it if you can get two front calipers. Sometimes, you may have to deal with a pair of brakes, with one long and one short bolt. If you used the long one in back, you can use the short one in front two different ways:
- Drill out the back of the fork crown and use an extra-long recessed nut. These nuts are commonly available for use in carbon fiber forks.
- Use the short recessed nut, but don't put it through the back of the fork. Instead, push it up into the inside of the steerer from the bottom. You can reach a 5 mm Allen wrench in through the hole in the back of the fork, and poke the short caliper bolt in from the front.
You may need to shorten the recessed nut slightly to get it to fit inside your steerer.
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- A vehicle in which the rider assumes a more-or-less horizontal position, usually reclining with the feet forward. Recumbent bicycles are potentially more aerodynamic than conventional "upright" bicycles, but tend to be more complicated mechanically. They are very comfortable, and are often quite well adapted for long-distance riding. Most recumbent bicycles have smaller-than-usual front wheels.
There are many different designs of recumbents. They fall into several classes which are known by arcane abbreviations:
Wheelbase categories:
- L.W.B. (Long Wheel Base) recumbents have the front wheel located in front of the "bottom bracket". LWB recumbents have straight, efficient chain runs. The downsides of the LWB design include poor weight distribution (too little on the front wheel), and general unwieldliness due to the greater overall length.
- C.L.W.B. (Compact Long Wheel Base) recumbents are a variation which usually uses small 406 mm (20") wheels front and rear, with the rear tucked somewhat under the seat to reduce the wheelbase.
- S.W.B. (Short Wheel Base) recumbents have the front wheel behind the bottom bracket. SWB machines are more maneuverable, and generally more compact. The downsides of the SWB design relate to interference between the front wheel and the drive chain. SWBs generally have to run the chain over an idler pulley or two, which causes a significant loss in efficiency.
Steering Categories:
- A.S.S. (Above Seat Steering) recumbents have tall handlebars, with the grips typically located just in front of the rider's shoulders.
- U.S.S. (Under Seat Steering) recumbents have the handlebars located below the seat, so the rider's arms hang down at his or her sides. This is a very comfortable position, and makes for easier mounting and dismounting. USS machines almost always use an indirect steering linkage, with a tie rod connecting the handlebars to the fork crown.
| Recumbent Pros & Cons |
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| Pro | Con |
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- Recumbents are generally more comfortable for the butt.
- Recumbents are generally more comfortable for the hands/wrists.
- Recumbents are generally more comfortable for the neck.
- Recumbents are more aerodynamic, potentially faster.
- If you crash a recumbent, you hit feet first.
- Recumbents are generally heavier.
- Recumbents have more complicated drivetrains, often with convoluted chain runs, due to need to avoid interference between the pedals and the front wheel.
- Upright bikes, are generally less expensive, partly due to simpler design, partly due to economies of scale in manufacture.
- Recumbents are usually more awkward to store or transport, due to their greater length.
- Recumbents are a bit harder to balance, due to their lower center of gravity.
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- Reflectors are supplied with most bicycles with the intent of making the biycle visible at night when illuminated by the headlights of another vehicle.
Reflectors alone are not sufficient for this purpose. Any bicycle used at night must have a headlight. This is the law, and common sense.
Although rear-facing reflectors are of some use, side and front reflectors accomplish nothing, since vehicles on a collision course with a moving bicycle don't have their headlights shining on the reflectors until it is already too late to avoid a collision.
There has been a long-running conspiracy among bicycle manufacturers to perpetuate the fiction that reflectors alone are enough for night riding. They have done this out of fear that they will be required to supply lights with new bicycles. For details, see John Forester's article on the subject.
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- Regina was a noted Italian manufacturer of freewheels and chains up through the early '90s. The Regina "Oro" ("Gold") chains and freewheels were the standard for high-end racing bikes in the 1970s and into the early '80s, but Regina lost ground to the better shifting Sedisport chains, and better shifting Japanese freewheels from Sun Tour and Shimano. The coup-de-grace for Regina was Shimano's S.I.S. system.
The word "Regina" meens "Queen" in Latin.
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A retainer is a clip, usually sheet-metal or plastic, that holds and separates the bearing balls in a ball bearing. The advantages of retainers are ease of assembly, and economy because the manufacturer can get by with fewer balls, if they are spaced apart by a retainer. Retainers are a good thing for headsets, and one-piece cranks, due to the ease of assembly issue. They are generally not so good for other bicycle bearings.
Conventional bottom brackets with loose balls can hold 11 1/4" balls per side. High quality retainer sets also have 11 balls. Cheaper retainers will only have 9 or even as few as 7 balls, and should not be used.
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- Reynolds, currently known as TI/Reynolds, is an old and very highly regarded maker of bicycle tubing. They pioneered the techniques of making butted tubing around the turn of the century, and their 531 (say "five, three, one") manganese-molybdenum alloy tubing was the standard of excellence for many decades. Newer formulations from Reynolds include 753 and 853.
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- Handlebar tape. This is a mistranslation of "ruban", and should be avoided--"tape" is the correct English term.
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- A frame or fork which does not have any built in mechanical suspension system. Conventional forks actually are designed to flex slightly over bumps, but they are still called "rigid" forks as compared with true suspension forks.
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- The outer metal hoop of a bicycle wheel. The rim does not include the spokes, nor the hub.
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- A pinch flat, or the damage suffered by the tire sidewall from similar causes.
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- In an upright handlebar, the "rise" is the vertical distance from the low point of the bar (the middle) and the high points (typically the grip area.)
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- A rivet is a cylindrical fastener which fits through a tight-fitting hole. The end of the rivet is then hammered or "peened" over so that it spreads out like a mushroom, so that the rivet will stay in place. Generally, rivets are one-time fasteners, for parts which are not expected to be dissasembled for servicing.
Rivets are commonly used to assemble derailers, fenders and saddles together. They are also used to assemble low-quality pedals and cranks/chainwheels.
The links of a bicycle chain are held together by rivets which, in most cases only have a slight thickening at the ends, rather than a seriously spread head. This allows chain links to be disassembled by partially removing the rivet, then driving the rivet back in with a chain tool.
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- In the broadest sense, this would refer to any bicycle designed to be ridden primarily on pavement.
Usually, the term "road bicycle" is used to refer to a sport bicycle with drop handlebars and narrow tires. Sometimes the term is used in an even more restrictive sense, to apply to a road racing bicycle.
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- In one sense, road racing is any racing that is done on roads, but the more usual sense is that of a mass-start race from one place to another, or possibly a loop course with long laps (as opposed to a criterium.) Since road races tend to be longer than criteriums, and the packs tend to be smaller and less dense than those in criteriums, bicycles designed for road racing tend to favor comfort more than criterium machines do, but to be less maneuverable. They may have lower bottom brackets, since there is less need to pedal through corners in a road race than there is in a short-course criterium.
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- A traditional type of utility bicycle, sometimes known as a "postman's bike". These usually have 37-635 (28 x 1 1/2) wheels, rod brakes, a chaincase, slack angles. Most of them are black. This is the predominant type of bicycle in Asia, the Netherlands (although Dutch roadsters are more likely to have rod-operated drum brakes)
Click for larger image. (64k)
See my articles on English 3-Speeds, and my 1954 Superbe Roadster (pictured above.)
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- Roller-lever brake
Some rod brakes use the rods to operate a drum brake, this set-up is popular in the Netherlands.
Most rod brakes use a "stirrup" which holds brake shoes that pull against the inner circumference of the rim. These are usually used with Westwood or Raleigh pattern rims, which have a ridge where the spokes attach, so there is no risk of snagging a spoke nipple with the brake shoes.
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- 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.
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- 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.
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- 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.
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- A type of brake which uses a triangular cam. It has two see-saw like arms, pivoted in the middle on cantilever-type studs. The cam is pulled by the cable, which is attached to the narrow end. As the cam is pulled, its sloping sides push outward on rollers which are attached to the upper end of the brake arms. Roller-cam brakes permit the use of variable ratios by making the sides of the cam curve instead of being straight. Typically this is done to make the shoes travel in toward the rim fast, then more slowly as they engage...this gives more mechanical advantage in the actual braking range of travel, while allowing the shoes to back off farther from the rim than they would be able to if the mechanical advantage was consistent throughout the travel range.
Compared to normal cantilevers, rollercams have the advantage of not protruding past the sides of the frame, which made them popular in the lae '80's when there was a fad for placing the rear brake under the chainstays...you couldn't use conventional cantilevers there, because the cranks would bump into them.
Unfortunately, roller cams are more difficult to set up than conventional cantilevers, and they make for more difficult wheel changes.
Roller-cam cantilevers do not work on cantilever studs made for conventional cantilevers, because conventional cantilever studs are mounted inward from the rim, while roller-cam studs are outward from the rim. "U-brake" cantilevers are interchangeable with rollercams.
With both roller cams and U-brakes, there is a tendency for the brake shoes to strike higher and higher on the rim as the pads wear. If the pads are not checked regularly, they eventually start to rub on the sidewall of the tire, which destroys the tire in short order.
The Odyssey "Pitbull" is a caliper-type rollercam unit, popular in BMX and recumbent applications.
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- A hand-operated brake that uses solid rods and pivots as a linkage from the handlebar to the brake unit. Roller-lever brakes are harder to work on than brakes operated by Bowden cables, but they are more reliable than cables, especially on bicycles which are subject to neglect and abuse. They are commonly found on roadsters.
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- Standard bicycle chain has rollers that smooth the engagement of the chain with the sprockets, as opposed to block chain.
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- A roller clutch (or "silent clutch" in Shimano terminology) is a type of freewheel ratchet mechanism which uses cams and rollers instead of pawls.
In addition to eliminating the annoying "tick-tick-tick" of a pawl-type freewheel, a roller clutch has less slop when drive force is applied to it...drive begins as soon as forward motion of the pedals starts, unlike a pawl-type freewheel which only drives once it has rotated far enough to let the pawls engage the notches of the ratchet ring.
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- 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.******
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- The distance a bicycle travels in one complete revolution of the cranks; development.
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- 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 ®
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- Revolutions Per Minute, a measure of speed of rotation. In bicycling, this is most often used in discussions of pedaling cadence.
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- See Shimano Models and Buzzwords
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- See Shimano Models and Buzzwords
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