The sprocket spins along with the hub or crank where it’s inserted, transferring the movement to the wheel. Each sprocket is made in one piece, and it can be made of aluminium, steel or titanium.

Key points:

· Threaded vs. Splined: sprockets can be threaded (standard 1.37” x 24tpi thread) or splined (Echo splines, Shimano HG cassette, etc.).

· Number of teeth: normally, 12 teeth rear sprockets are used for 20” bikes, 14t for 24” bikes and 15t for 26” bikes. Kid bikes usually have a 13t or 14t sprocket.

· Material: steel sprockets are the most popular and reliable, but are heavier than aluminium and titanium sprockets.