Gearbox (Gears)

The gearbox contains pairs of toothed gears on two parallel shafts. By selecting different pairs, the rider changes how many times the engine turns for each turn of the rear wheel, so the engine can stay in its useful rpm range whether the bike is pulling away or cruising.

Most motorcycles have a sequential gearbox operated by a foot lever, typically with five or six gears and neutral between first and second. The gears are selected by shift forks moving dogs on the gears, guided by a rotating selector drum. On most bikes the gearbox shares its housing and oil with the engine.

Notchy shifting, jumping out of gear or false neutrals point to worn dogs, bent forks or clutch problems. Keep the oil fresh and change gear with a firm, deliberate movement.