SEAT POST A hollow tube that holds the saddle and is inserted into the seat tube.
SEAT STAY The frame tube joining the bottom bracket shell and rear drop-out.
SEAT TUBE The frame tube that holds the seat post.
SIDEWALL Part of the tyre between the tread and rim.
SPROCKET A cog turned by the chain. Combined with other sprockets, it forms a cassette or block.
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 term that combines 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 a 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.
THREADS The spiral grooves cut into metal that allow separate parts to be screwed or bolted together.
TOP TUBE The frame tube that joins the seat tube to the head tube.
TRANSMISSION A bike’s transmission is made up of those parts that transfer the rider’s energy into forward motion – the pedals, chain, chainset and sprockets. See also Drivetrain.
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 tyre 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 quicker than a heavy oil through a given damping mechanism. This results in a faster-acting suspension system or reduced damping.
WHEEL JIG A stand that holds a wheel so that its rim runs between two jaws. Used in truing a wheel after replacing a broken spoke.