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Bicycle Glossary - R


R & R - Remove and replace, a term sometimes used by bicycle professionals which refers to the concept of replacing damaged parts with no consideration of repairing them. R & R makes sense in many modern situations from a purely economical point of view, where the labor cost of repair exceeds the cost of the part plus the lesser labor of removing and replacing it. In other times and places, many things we throw away today were repaired. 

Racing - Competing on bicycles for speed. There are many types of racing. The most common are: Road racing, time trials (which see) off-road racing which is also known as mountain bike racing or BMX racing (which see), cyclocross (which see), track racing (which see), and stage racing (which see).

Racing jersey - A special shirt worn for racing. Synonym: Jersey.

Racing shorts - Shorts worn for racing and touring. Synonym: Shorts - which see.

Randonneur - A style of handlebar named after a successful racer. This is a style similar to Maes (which see), a downturned style found on thin tire road racing bikes, but with a slight upward curve on either side of the middle, and a slight flare outward of the lowest parts, so the rider's forearms do not bump into the upper portion of the handlebar.

Ratchet - 1. A stepped surface over which pawls (little spring-loaded flippers) run. When the ratchet or pawls are turned one way, they engage. When turned the other way, coasting is possible. Ratchets are found in freewheels and planetary gear sets. See also: Pawl. 2. A handle to which sockets are attached for turning nuts and bolts.  The handle can work in a limited area by swinging back and forth, slipping in one direction, and turning the fastener when swung in the other direction.

Rattrap - A colloquial term with two meanings. It can mean a luggage carrying platform which mounts over the wheel, or a style of pedal which has a metal cage.

Reaction arm - By pedaling backward about an eighth-turn of the pedals, a coaster brake can stop a bicycle's rear wheel easily. The torque developed at the hub is tremendous. Normally, that torque would spin the coaster brake's axle within the dropouts - not a desirable condition. Therefore, to counteract the force, a steel arm comes out of the left side of the coaster brake, and is fastened to the chainstay a few inches away. This is the reaction arm. Synonym: Brake arm.

Rear derailleur - A cable-operated guide mechanism that allows the rider to shift the chain from one sprocket to another on the freewheel of the rear wheel.

See also: Front derailleur

Recumbent -  A bike that's built close to the ground for less wind resistance, and lower center of gravity. Also called "bent."

Repair stand - A device for holding bicycles up at a comfortable working height, and allowing the repair person to spin wheels. Synonym: Workstand - which see for more details. 

Replica - A copy of an antique bicycle.

Reynolds - An English manufacturer of steel alloy bicycle frame tubing. 

Right-threaded - Nuts and bolts that are threaded in the conventional direction. To install or tighten a right threaded part, you turn it in the same direction you would turn a pickle jar lid when you're putting it back in the fridge.  See also: Left-threaded.

Rim - The metal ring which holds the tire and tube. The whole wheel, consisting of rim, spokes and hub is often mistakenly referred to as "rim."

Rim strip - A strip of rubber, plastic or cloth that protects the inner tube in a wheel from being punctured by wearing against the tops of the spoke nipples or the rim. 

Road bike - A bicycle with thin tires, large frame, and light weight that's designed for maximum efficiency for riding on pavement.

Rohloff - A manufacturer of rear wheel hubs using multiple planetary gear sets achieving 14 speeds with an incredibly wide range of gearing greater than 500%. Rohloff hubs cost close to $1,000 but are very strong and reliable. The only critique offered by many Rohloff riders  is that there is a sudden momentary stiffness in pedaling when you switch from 7th to 8th gear as it engages 14th gear before settling into 8th.

See also: Planetary Gearing, Nexus

Roller bearing - A bearing that uses cylindrical rollers instead of balls.  Roller bearings are stronger than ball bearings for handling radial stresses, but do not handle linear stresses well.  A variation of roller bearing uses tapered cylindrical rollers to accommodate radial stresses, and linear stresses in one direction only.  Roller bearings are seldom seen in bicycle components.

See also: Ball bearings, Needle bearings.

Rolling a tire - A situation in which sew-up (tubular) tires roll off the edge of the rim while cornering. These tires are glued to rims that are not as concave on their outer surface as conventional rims. Rolling a tire is usually caused by improper gluing, but can happen in unusual cornering situations, such as hitting a stone or edge in the pavement while cornering. With properly glued sew-up tires, rolling a tire is very rare. 

Rotor - A device surrounding the handlebar stem on freestyle bikes that allows the handlebar to turn around and around without tangling up the rear brake cable


Anything missing or need greater coverage? Let me know - Jeff

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Although I have attempted to cover the major safety issues, I cannot be responsible for your use of this information. Working on bicycles is dangerous if you do it without considering consequences of bolts left loose, known problems which are ignored, things which should be replaced but are glued instead, and so on. Proceed carefully at your own risk and use common sense. Jeff Napier, and all agents associated with this information, do not offer any guarantee or warranty for your use of this information

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