Sheldon Brown's Bicycle Glossary U-V
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U-brake
- A form of cantilever brake that 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 it, as with conventional cantilevers. It uses the same type and placement of studs as roller-cam brakes do.
In 1986-88 there was a fad for equipping mountain bikes with U-brakes mounted underneath the chainstays, providing a nice clean look to the seat stay area of the bicycle, and a somewhat simpler cable routing. In addition, since the chain stays are larger and more rigid than typical seatstays, the "problem" of flexing of the studs under load was reduced. Conventional cantilevers 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 chain stay-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, they would hit higher and higher on the rim. Eventually, they would overshoot the rim and start rubbing on the tire sidewalls, one of the fastest known ways to destroy a tire.
Adjusting U-brakes:
First, remove the arms from the studs and, make sure the studs are free of rust. Coat the studs liberally with grease (this is VERY important!)Install the arms at their maximum spread and tighten the bolts that hold them to the frame. This is how you set the springs. Only connect the transverse cable after this has been done.
There is usually a small setscrew on the side of one of the arms for fine adjustment of spring balance.
Set the transverse cable as short as possible for best braking. Check the brake-shoe adjustment frequently--due to the location of the pivot studs on these brakes, as the brake shoes wear they hit higher and higher up on the rims. If you don't keep on top of the adjustment, they will eventually start rubbing on the tire sidewall. Many thousands of tires have been ruined this way.
- The inaccessible location made it very difficult to service or adjust the brakes.
U.C.I.
- Union Cycliste Internationale, the world-wide governing body of road and track racing.
U.C.P.
- 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.
UD ®
- See: Ultra-Drive
Ultegra ®
- See Shimano Models
Ultra-Drive ®, (UD ®)
- Campagnolo's equivalent to Hyperglide
Ultra Spacing
- 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., allowing 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. A 7-speed freewheel could be used with 126 mm dropout spacing.
Ultra spacing, 5 mm center to center,is identical with the spacing of Shimano 7-speed cassettes; Shimano 7-speed or 8-speed shifters can be used to index these freewheels. This shifting isn't as clean as with Hyperglide cassettes, but it is much nicer than friction shifting.
Ultra spacing 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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UMCA
- The Ultra Marathon Cycling Association, US sanctioning organization for Centuries, Double Centuries, Brevets, Randonnées, Cross-state records, 12 and 24-hour races and qualifier rides for RAAM (the Race Across America).
Uniglide ®
- An older Shimano buzzword for rear sprockets with twisted teeth for improved shifting. Uniglide was replaced by Hyperglide, a more sophisticated system of special sprocket-tooth shapes.
See also my article on Shimano Cassettes.
Uniglide ® Hyperglide ® Universal
- Italian parts manufacturer, the leading Italian brake before Campagnolo entered the brake market.
Universal Joint
- 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 the trailer hitch of single-wheel trailers.
Upright
- 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 handlebars are sometimes referred to as "mountain bike " handlebars, but that's sloppy usage, because upright handlebars are also used on most bikes designed for street use.
- Upright bicycles are conventional bicycles, providing an upright riding position, as opposed to recumbents. See also wedgie.
- 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.
Upshift
- 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.
U.S.C.F.
- United States Cycling Federation, the principal governing body of road bicycle racing in the U.S.; known until 1975 as the Amateur Bicycle League of America (A.B.L.A) and now one branch of USA Cycling, which also includes the USPRO (track),NORBA (mountain biking), and NCCA (collegiate cycling)
U.S.S.
- Under Seat Steering
U.S.T.
- Universal System Tubeless. The most common system of tubeless tires/rims for bicycle use.
Unicrown
- 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.
V1, V2 ®
- Shimano Octalink ®
cranks come in one of two different spline
patterns:
- The original "V1" type for:
- XTR (BB-M952 9-speed)
- Dura-Ace (BB-7700 9speed)
- Ultegra (BB-6500 9-speed)
- 105 (BB-5500 9-speed)
- The later "V2" type for:
- Deore XT (ES70/71)
- Deore LX (ES70/71)
- Deore (ES50/51)
The V2 BBs work with FC M752, FC M751, FC M572, FC M571, FC M510-8 and FC M440-8 cranks.
- Tiagra 2005 (4401,4404)
- Sora 2005 (3301,3304)
- The original "V1" type for:
Valve
- The part of the inner tube that permits air to be added. There are three types used on bicycles, Presta, Schrader, and Woods
Schrader valve Presta valve Woods valve Valve Cap
- A metal or plastic screw-on cover intended to protect the innards of a tire valve from dust and other foreign matter.
Presta valves have non-removable, built-in caps, and external caps are unnecessary.These redundant caps come with Presta tubes and tubulars so that the pointy end of the valve won't puncture a spare tube or tubular while it is rolled up. There's no reason to use them in actual riding
V-Brake ®
- A Shimano trademark for a direct-pull cantilever brake, which does not use a separate transverse cable. A V-Brake 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 which 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 with conventional cantilevers.
"V-Brake" is a Shimano trademark.
Vélo
- French for "bicycle", commonly used as a root for compound words relating to cycling. Short form of "vélocipède".
Velodrome
- A bicycle racing track.
V.I.A.
- Japan Vehicle Inspection Association, a quasi-official agency that promotes standardization and minimum quality standards for Japanese vehicles.
In the post WW2 era, most Japanese industries acquired similar governing bodies under the J.I.S.C. (Japanese Industrial Standards Committee). These agencies helped to turn around the international reputation of Japanese products from the former stereotype of cheap copies of western designs to their present high reputation for quality and reliability.
Vice
- The opposite of "virtue."
Also, British spelling of "vise ."
Vise
- A very useful tool for holding parts solidly to a workbench. A good vise, bolted to a solid workbench, is one of the most basic requirements of a well equipped work area.
Vise-Grip ®
- 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. Vise-grips should not be used on un-damaged fasteners, because their serrated jaws will damage the part they are used on.
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Since May 4, 1996
Copyright © 1996, 2007 Sheldon Brown
Revised April 29, 2010 by John Allen
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