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 form of cantilever brake, which works like a centerpull caliper. The "L"-shaped arms cross over above the tire, so the left brake shoe is operated by the right side of the transverse cable. A U-brake uses studs that are above the rim, rather than below the it, as with conventional cantilevers. They use the same type and placement of studs as rollercam brakes do.
In 1986-88 there was a fad for equipping mountain bikes with U-brakes mounted underneath the chain stays. This provided a nice clean look to the seat stay area of the bicycle, and provided a somewhat simpler cable routing. In addition, since the chain stays are larger and more rigid than typical seat stays, the "problem" of flexing of the studs under load was reduced. Conventional cantileves cannot be mounted on the chainstays, because the cantilevers would get in the way of the cranks.
Although U-brakes were cool looking and powerful, the fad died quite abruptly when people actually started using the bikes that were sold with chainstay-mounted U-brakes. They had several serious drawbacks:
- The inaccessible location made it very difficult to service or adjust the brakes.
- They complicated the process of wheel removal.
- They tended to get clogged with mud.
- Due to the high-mounted studs, if you didn't monitor the brake shoe wear carefully, as they would wear, they would hit higher and higher on the rim. Eventually, they would overshoot the rim and start rubbing on the tire sidewall. This is one of the fastest known ways to destroy a tire.
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- Union Cycliste Internationale, the world-wide governing body of road and track racing.
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- Universal Chrome Plating, a process for chrome-plating cheap steel spokes so that they look shiny when they are new. U.C.P. spokes are used on low-end bicycles because they are cheaper than stainless steel spokes.
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- See Shimano Models
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- An early type of 6-speed freewheel made by Sun Tour, in which the sprockets were closer together than those of a 5-speed or normal 6-speed freewheel. This allowed the use of a 6-speed freewheel on a hub built for a 5-speed cluster, in a frame with 5-speed (120 mm) dropout spacing.
This was made possible by the development of chains in which the ends of the rivets did not protrude far past the side plates. 7- and 8-speed freewheels are also "Ultra" spaced, but the term is mainly used to describe the narrow 6-speed units.
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- An older Shimano buzzword for rear sprockets with twisted teeth for improved shifting. This was replaced by Hyperglide, a more sophisticated system of special sprocket tooth shapes.
See also my article on Shimano Cassettes.
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- Italian parts manufacturer, the leading Italian brake before Campagnolo entered the brake market.
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- A mechanical linkage which allows two parts to flex with respect to one another, but not to rotate. The primary bicycle application of universal joints is for single-wheel trailers.
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- Upright handlebars are used on most of the world's bicycles. They permit a fairly erect posture of the upper body, and are more comfortable for cyclists who ride at a low intensity level. Cyclists seeking greater speed or efficiency often prefer drop handlebars.
- Upright bicycles are conventional bicycles, providing an upright riding position, as opposed to recumbents.
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- The act of shifting to a higher gear. In the case of derailer gearing, this means shifting to a smaller rear sprocket, or a larger chainwheel.
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- Under Seat Steering
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- A type of fork in which the upper ends of the blades bend together to attach directly to the steerer, eliminating a separate crown. This style of fork is common on mountain bikes and hybrids.
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- The part of the inner tube that permits air to be added. There are three types used on bicycles, Presta, Schræaeder, and Woods
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-removeable, 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 Schræder 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!
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- A type of cantilever brake 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 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 which mantains 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.
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- French for "bicycle", commonly used as a root for compound words relating to cycling.
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- A bicycle racing track.
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- A type of locking pliers. It has a toggle link mechanism in one leg, and an adjusting thumbscrew in one of the legs. Vise-Grips are operated much the same as quick-release mechanisms.
This is a tool of last resort for removing nuts or bolts whose heads are so badly damaged that the proper wrench will not fit them. They should not be used on un-damaged fasteners, because their serrated jaws will damage the part they are used on.
- ******
- A metal disc with a hole in the middle.
There are several different types of washers used on bicycles, to serve different purposes:
- Flat washers are commonly used between nuts or bolt heads and the parts that they tighten against. For most fasteners, it is desirable that the part that is turned by the wrench or screwdriver have a washer under it to protect the surface from the turning fastener. Flat washers are also commonly used to spread out the load when a fastener is attached to a thin or fragile part.
- Lock washers have one or more directional teeth that act like pawls against the bearing surface of the fastener. These make it easier to turn the fastener in the tightening direction than in the loosening direction, so it is less likely that the nut or bolt will rattle loose.
- ******
flat washer, keyed washer, spacer, radiussed, serrated washer anti-roation (S-A)
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- 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 newer 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 overtightened.
- 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.
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- Disparaging term used by recumbent fans to describe a conventional upright bicycle.
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- A noted manufacturer of rims and (formerly) brakes. Formerly, Weinmann was based in Belgium and Switzerland, but the current Weinmann company is U.S. based.
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- A process of joining similar metals by heating them so that they melt into one another. Compare to brazing.
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- The old-fashioned type of rim usually seen on roadsters. Westwood rims have rounded sides, so they are not suitable for use with caliper brakes. They are designed to be used on bikes with rod brakes, where the brake shoes rub on the inside circumference of the rim. The Westwood profile has a ridge between the braking surfaces. The spoke holes are drilled into this ridge, and the ridge protects against the brake shoes hitting the nipples.
Westwood rims are most commonly seen in the 635 mm (28 x 1 1/2) size, but they were made in most of the middleweight British sizes.
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- Handlebars located below the seat of a U.S.S. recumbent.
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- A hub, rim, and spokes all together; may also include the tire and tube.
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- A wheelie is the act of using a combination of pedal thrust and weight shifting to raise the front wheel into the air. A skillful freestyler can lift the front wheel high enough that the center of gravity moves over the rear wheel, then ride the bicycle as if it were a unicycle. The correct verb to describe the act of doing a wheelie is "pop". Wheelies often cause great stress on a bicycle's fork when the front wheel comes back down.
A "nose wheelie" results when the front brake is applied hard enough to cause the rear wheel to lift off.
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- Also known as a "high-riser", "Stingray", "polo bike", "banana bike", "Chopper". The most horrible children's bikes ever made. Some who had them as children retain a sentimental attachment to them, so there is an active market in "collectible" wheelie bikes, but they were, in my considered opinion, an unmitigated disaster.
Early wheelie bikes were home made by adapting a bike made for a small child for use by a larger child. They would use a frame from a 20" wheel child's bike, install tall "ape hanger" handlebars and a "banana seat" which extended back over the rear wheel. The resulting weight distribution created a bicycle that would do a wheelie with the slightest effort.
The American bicycle industry, led by Schwinn with it's "Stingray" and "Krate" models, jumped on this early '60's fad. They made a lot of short-term profit, but, I believe, this led to a serious long-term setback for the American bicycle industry.
Before the wheelie bike craze, there was a well-established progression of frame sizes for growing children, from 16", to 20", to 24" and finally to 26" wheel bicycles. The wheelie bike killed the 24" bike market, because these bikes would sort-of fit children who should really have been riding on 24" wheels.
Wheelie bikes also greatly re-inforced the idea that the bicycle was a child's toy, not a serious vehicle. Wheelie bikes were easy to do wheelies on, but their awkward riding position made them hellishly uncomfortable to actually ride more than a half-mile at a time.
Wheelie bikes in turn were killed by BMX bicycles, which are much more "rideable", but the 24" market never completely recovered.
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- The distance from the center of the front wheel to the center of the rear wheel. In general, a bicycle with a longer wheel base is more stable and comfortable; one with a shorter wheel base tends to be more maneuvrable. See: angles.
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- A cyclist who drafts other cyclists without taking his or her share of pulling.
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- Sir Joseph Whitworth was one of the great inventors of the 19th century. He invented the milling machine, and was the first to manufacture all-metal machine tools. I believe that he was also connected with the Rudge bicycle company (later acquired by Raleigh).
He was also one of the first to establish a standardized set of screw threads and wrench sizes. Whitworth fasteners were used in British industry up until the late 1960's, when Britain adopted the metric system. The Whitworth system is now virtually extinct.
Whitworth fasteners used a 55 degree thread angle. The wrench sizes were confusingly marked, the wrenches are all larger than you would think. This is because the dimension given on a Whitworth wrench is the diameter of the bolt thread usual for that size wrench, rather than the size of the head. Some Whitworth wrenches even have two marked sizes, because the same head size is used with one coarse thread and a different diameter fine thread.
Some of the smaller sized Whitworth threads are interchangeable with S.A.E. threads.
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- 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.
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- In many ways, wood is an ideal material for bicycle rims, and most bicycles in the early part of the century were equipped with them. They are light, strong, and resilient. Wood rims are not suitable for "clincher" tires, but worked well for other types.
Wooden rims went out of style for road bicycles when rim brakes came in, but continued to be use on the track well into the '40's. They were eventually outlawed for competition because of their dangerous failure mode: When a highly-tensioned racing wheel with a metal rim was damaged, it would fold up, but it would stay together. Similar wood-rim wheels, when overstressed, would suddenly turn into a cloud of sharp, dangerous splinters.
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- There is a third type of valve, very rarely seen, which has a bottom similar to a Schræder and necks down to about the size of a Presta. This is a Woods valve, also known as a "Dunlop" valve. Woods valves were formerly popular in the British Isles and Asia. These low-tech valves work with rubber tubing and spit. You can pump them up with a Presta pump.
If they don't hold air, you can unscrew the knurled ring that holds the valve core (the "Presta-sized" part) in place. You should see a short length of rubber tubing covering the inner part of the core. If the rubber tubing it old and perished, the valve won't work. Some patch kits include short lengths of replacement rubber tubing for this purpose. When installing new tubing, lubricate the valve core with spit before slipping the tubing in place.
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- 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 which 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.
- 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 which 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. ****nutdrivers; 6-point/12-point)
- Spanner Wrenches use pins to engage holes or notches in the fastener.
- Pin spanners usually use two pins which 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
- Spline Wrenches (including Torx, freewheel, etc.)
- Adjustable Wrenches can be adjusted to fit different sized fasteners, usually by the use of a thumb screw. 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 spacings. The spring-loaded Park SPA-1 (green) adjustable pin wrench 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 undertightening the part involved.
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- ****
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- See Shimano Models
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- See Shimano Models
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- A fitting used on center-pull caliper and cantilever brakes which use a transverse cable. The yoke is the part that connects the main cable to the transverse cable.
This is frequently misspelled as "yolk", which is part of an egg.
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- An electronic rear derailer made by Mavic.
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- A brand of aftermarket fairings.
