thumb|16T type sprocket Do: Sprocket diameter Dp: Pitch diameterA sprocket is a profiled wheel with teeth that meshes with a chain, track or other perforated or indented material. It is distinguished from a gear in that sprockets are never meshed together directly, and from a pulley by not usually having a flange at each side. Sprockets are used in bicycles, motorcycles, cars, tanks, and other machinery either to transmit rotary motion between two shafts where gears are unsuitable or to impart linear motion to a track, tape etc. Cycles In the case of bicycle chains by varying the diameter (and therefore, the tooth count) of the sprockets on each side of the chain, modifying the overall gear ratio of the chain drive is possible. This is the basis of Derailleur gears. A 10-speed bicycle, by providing two different - sized driving sprockets and five different-sized driven sprockets, allows up to ten different gear