Mechanical Info

Glossary of Terms

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A glossary of commonly used bike terms.

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Air Pressure

The amount of compression of the air in a bike tire. The tire pressure reduces the rolling resistance, and provides suspension to the bike, increasing the comfort of the ride. In the U.S. pressure is usually measured in pounds per square inch (psi). The typical modern fat tire rates at a pressure of up to 65 psi. The typical thin tire rates up to 100 pounds per square inch. The exact recommended pressure varies from one model of tire to another, and is typically imprinted on the side of the tire.

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Blowout

A bursting of a tire and inner tube., usually associated with a loud popping noise. This can be caused by filling a tire past the recommended air pressure, filling a tire that is mounted incorrectly or that is damaged, and can happen while riding and hit an large obstacle or sharp object. A blowout will typically necessitate a replacement of the tire and inner tube.


Bottom Bracket

A bicycle component that consists of the crank axle (bottom bracket spindle) and ball bearings. Crankarms are bolted onto the bottom bracket.


Brakes - Linear Pull

This is the generic term for a V-Brake. The V-Brake name is a trademark of Shimano.

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Cassette

A group of sprockets designed to be used with a freehub.


Chain

The key drivetrain component. Power is transmitted from the crankarms to the rear wheel through the chain.


Chainring

Large sprocket(s) attached to the right crankarm which drive the chain.


Chanistays

The frame tubes that run horizontally from the bottom bracket shell to the rear dropouts where the wheel is attached.


Coaster Brakes

A type of brake, used mainly on kids’ bikes and cruisers that is engaged by pedaling backwards.


Crankarm

A type of brake, used mainly on kids’ bikes and cruisers that is engaged by pedaling backwards.


Crankset

The drivetrain parts consisting of the crankarms and chainrings.

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Derailleur

Front and rear gear changing devices that move the chain across the cassette and the front chainrings. Derailleurs are operated by pressing the shifters to move the derailleur cables.


Down tube

The portion of the frame that runs from the head tube to the bottom bracket shell.


Dropouts

The slots in the frame and fork in which the rear and front wheels, respectively, are mounted.

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Fork

Part of the bicycle that holds the front wheel. The fork steerer tube is inserted into the head tube.


Fork Suspension

A fork that is designed to absorb shocks using coil springs or air springs. Generally found on mountain bikes, comfort bikes and some hybrid bikes.


Frame

A welded set of tubes to which all of the bicycle components are connected. Frames generally have the following parts: head tube, top tube, down tube, seat tube, seat stay, chain stay and bottom bracket shell.


Freewheel

The ratchet mechanism that allows the rear wheel to turn without turning the crank. Necessary to allow coasting. It can be part of the hub or part of the freewheel cluster, depending on the design.


Front Derailleur

Bicycle component that moves the chain across the front chainrings thus changing the gear ratio and achieving what is referred to as a gear shift.

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Handlebar

The flat or riser bar that grips, brake levers, and shifters are attached to.


Head tube

Vertical frame tube onto which the top tube and down tube are attached. The fork steerer tube is inserted into the head tube.


Hub

Bicycle component located in the middle of the wheel from which the spokes radiate outward.

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Inner tube

The air bladder which hold the air pressure within the tire of the bicycle. The tire provide the structure and protection, while the inner tube maintains the air pressure.

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Patch kit

A selection of tools and materials that allows the repair of bicycle inner tubes.


Pedal (Flat, clip, and clipless)

A flat-pedal in the one we’re all familiar with. It’s flat and doesn’t require special shoes. Pedals with toe clips hold your foot on to the pedal. And clipless pedals actually require special shoes that attach to the pedal.


Puncture

A hole or leak in the inner tube, causing loss of air pressure. The result is a flat tire.

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Quick-release

A device typically used in place of a static bolt allowing for easy tool free removal or adjustment of a component. Frequently used on wheel hubs and seat posts.

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Rear Derailleur

Bicycle component that moves the chain across the rear cogs thus changing the gear ratio and achieving what is referred to as a gear shift.


Rim

The metal hoop which holds the tire and tube, which is attached to the hub by spokes.


Rim strip

A strip of rubber, plastic or cloth used in clincher type rims that protect the inner tube from being punctured by wear against the tops of the spoke nipples or the rim.

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Saddle

Cyclist's name for a bicycle seat.


Seat post

Frame component onto which the saddle is attached. The seat post is inserted into the seat tube.


Seat stays

Paired frame tubes running from the seat tube to the rear dropouts.


Seat tube

Frame component into which the seat post is inserted.


Seating a tire

The way a tire is mounted on a rim. A properly seated tire will be nicely round producing a smooth ride. An improperly seated tire can have bulges or flat spots, and can even blow out if very poorly seated.


Shifters

The mechanism, generally found on the handlebars, that move shift cables which in turn move derailleurs in order to change gears.


Skewer

The portion of a wheel quick-release mechanism that extends through the hub axle.


Snakebite flat

A flat tire caused by pinching the tire and tube between the rim sidewalls and a rock or other obstruction. It usually causes two parallel punctures in the tube that look like a snake bite.


Spokes

Spokes are wires that connect the hub to the rim on a wheel.


Stem

The component that holds the handlebars and mounts to the steerer tube.

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Tire bead

On clincher tires, the metal, fiberglass, or plastic cable running along the edge of both sides of the tire, called the "bead." This is molded into the edges of the tire. The bead seals the tire against the rim once filled with air pressure, keeping the tire on the rim.


Tire tube

A tool for removing tubular tires from rims used to pry the tire over the edge of the rim.


Top Tube

Horizontal frame tube running from the seat tube to the head tube. When shopping for a bike, you generally want 1-2 inches of space between the top tube and your crotch.


Truing a wheel

The process of making a wheel truly round by adjusting spoke tension. Not a job for amateurs.

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U-Brake

A style of brake that push pads into the rim to slow the wheel.

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V-Brake®

Shimano's trademark name for linear pull brakes.


Valve

Bicycle inner tubes have valves through which air can be put into the wheels. The two common types of valves are Schrader valves, which are the same as the valves found on car tires, and Presta valves, which are smaller and lighter in weight. Huffy rides use Schrader valves.

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Wheel

A complete commonly consisting of a tire, inner tube, rim strip, rim, spokes and a hub.


Wheel alignment

The condition of the roundness, and lateralness or planeness of a wheel. A properly aligned wheel will produce a smooth ride, free of wheel induced vibration, wobble or bounce.


Wheelsmith

A bicycle professional who specializes in building and/or repairing wheels.


Work stand

A tool that holds a bicycle off the ground for convenient repair.

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