Most motorcycles have a manual, five-speed transmission. The transmission consists of a series of gears, shafts, and other parts that control the forward motion of the motorcycle and enable it to maintain high cruising speeds. To change gears, the rider activates a clutch lever on the left handgrip to disengage engine power from the transmission, then shifts a foot-operated gear lever on the left side of the motorcycle. Some motorcycles have automatic transmissions, which eliminate the need for a clutch and manually shifted gears.
On most motorcycles, the transmission delivers engine power to the rear wheel via a drive chain. Chains stretch with age and require periodic adjustment. In some motorcycles, a cogged rubber drive belt or an enclosed drive shaft replaces the drive chain. Belts and drive shafts do not require adjustments and operate more quietly than chains.