Sprocket is a kind of wheel with cogged sprocket, which is used to mesh with the block with accurate pitch on the chain link or cable. Sprockets are widely used in chemical industry, textile machinery, escalators, wood processing, three-dimensional parking garages, agricultural machinery, food processing, instrumentation, oil and other industries. The bicycle sprocket is made of high-strength steel to ensure that it reaches the required tension.

The chain, also known as vehicle chain and roller chain, is installed on the coupling wheel and flywheel. Its function is to transfer the pedal force from the crank and sprocket to the flywheel and rear wheel to drive the bicycle forward.