ALLEN KEY -- Hexagonal tool that fits Allen bolts.
BLOCK -- Cogs fitted to a FREEWHEEL.
BOSS -- Threaded metal fixture on a bicycle frame to which an item such as a bottle cage or a pannier rack is attached.
BOTTOM BRACKET -- Rotating unit that connects the CRANKARMS.
BOTTOM OUT -- A word that describes the point when a SUSPENSION fork or shock absorber reaches the limit of its travel.
BRAKE-LEVER HOOD -- The body in which the brake lever sits, connecting it to the handlebar.
BRAKE TRAVEL -- The distance a brake lever moves before the brake pads engage the braking surface on the rim or hub of a wheel.
CASSETTE -- A collection of cogs that fit on the rear wheel's FREEHUB.
CHAINRING -- A toothed ring attached to the CRANKARMS that drives the chain and, in turn, the cogs and the rear wheel of a bicycle.
CHAINSTAY -- The frame tube joining the BOTTOM BRACKET shell and rear dropout.
CRANKSET The assembly of CHAINRINGS and CRANKARMS.
CLEAT -- A plastic or metal plate that fits on the sole of a cycling shoe and engages with a CLIPLESS PEDAL to hold the foot on the pedal.
CLIPLESS PEDAL -- A pedal with a mechanism to engage the cleat on the sole of a cycling shoe and hold it securely in place. Called clipless because they replaced pedals that had toe clips and straps.
COG -- A circular metal object with teeth that is turned by the chain. Combined with other cogs, it forms a CASSETTE or BLOCK. Cogs are sometimes called "sprockets."
COMPRESSION -- The action of a suspension system when it absorbs an impact from the terrain. The term refers to the compression of the spring.
CRANKARM -- The lever that joins the pedals to the CHAINRINGS and transfers energy from the rider's legs to the DRIVETRAIN of the bike.
DAMPING -- The process that absorbs the energy of an impact transmitted through a suspension system. It controls the speed at which any form of suspension responds to uneven terrain.
DERAILLEUR GEARS -- A system that shifts the chain between COGS on the rear wheel (rear derailleur) and between CHAINRINGS attached to CRANKARMS (front derailleur); it allows multiple gearing on bikes.
DOWN TUBE -- The frame tube that joins the bottom-bracket shell to the head tube.
DRIVETRAIN -- The assembly of pedals, CRANKSET, chain, and cogs that drives the bike forward by converting the rider's leg power into wheel rotation.
DROPOUT -- A slotted plate at the end of the fork blades and stays, into which the axle of a wheel is attached.
FREEWHEEL -- A mechanism that does the same job as a FREEHUB but can be screwed on or off the hub.
GEAR-SHIFT LEVER -- The control mechanism, usually on the handlebar, used to initiate gear-shifts.
GRUB SCREW -- A headless, threaded bolt that has a single diameter throughout its length.
HEAD TUBE -- The frame tube through which the steerer tube runs.
HEXAGONAL BOLT OR NUT -- A threaded bolt with a hexagonal head, or a hexagonal nut that fits onto a threaded bolt.
HYDRAULIC -- A type of mechanical system that uses compressed fluid to move an object.
NEGATIVE SPRING -- A device that works against the main spring in a suspension system. In compression, for example, a negative spring works to extend the fork, helping to overcome the effects of STICTION.
NIPPLE -- The piece of metal attached to the end of a cable that secures the cable in the control lever.
Non-Recreational Biking -- Any time a bicycle is used for utilitarian and/or transportational purposes, such as commuting, shopping, running errands, etc. Said another way, non-recreational biking is when the bicycle is used as a realistic alternative to automobile transportation. This does not mean you can't simultaneously have fun or get a good workout!
Recreational Biking -- When a bicycle is used strictly for leisurely riding, mountain biking, racing, exercising or other athletic use.
SEAT STAY -- The frame tube joining the bottom bracket shell and rear dropout.
SEAT TUBE -- The frame tube that holds the seat post.
SIDEWALL -- Part of the tire between the tread and rim.
STEERER TUBE -- The tube that connects the fork to the stem and handlebar.
STEM -- The component that connects the handlebar to the steerer tube.
STICTION -- A combination of the words "static" and "friction." It describes the tension between moving and static parts at rest, such as the seals and stanchions in a suspension fork.
STOPPER PIN -- The end of a cantilever or V-brake return spring that fits into a locating hole on the bike's brake-mounting bosses.
SUSPENSION -- An air/oil or coil/oil system that absorbs the bumps from a trail or road. The system is either integrated into the fork or connected to the rear wheel via a linkage.
TOP TUBE -- The frame tube that joins the seat tube to the head tube.
TRAVEL -- A term that refers to the total distance a component moves in carrying out its purpose. For example, travel in a suspension fork is the total distance the fork has available to move in order to absorb a shock. Brake travel is the distance a brake lever must be pulled before the brakes fully contact the braking surface.
TREAD -- The central part of a tire that makes contact with the ground.
VISCOSITY -- A rating system for oils, which also refers to the weight. A light oil has low viscosity and moves more quickly than a heavy oil through a given damping mechanism. This results in a faster-acting suspension system or reduced damping.
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