To provide a bicycle which adopts a gear mechanism to reduce the weight and scale, considerably reduces the vertical distance as compared with a conventional bicycle, and adds new functions in accordance with the intended use in the reduced space.

The bicycle has a gear mechanism 8 including: a first gear 19 which is located outside a front fork 3 and has a central portion fixed to a crank shaft 10; a bearing 21 provided to the front fork 3; an interlocking shaft 22 rotatable about the bearing 21; a second gear 20 which is located outside the front fork 3 to mesh with the first gear 19 and has a central portion fixed to the interlocking shaft 22; a third gear 23 which is located inside the front fork 3 and has a central portion fixed to the interlocking shaft 22; and a fourth gear 24 which is fixed to a hub tube 27a to mesh with the third gear 23 and has a central portion fixed to a hub 27. The gear multiplication rate for the rotation of a drive wheel is related to the rotation of the crank shaft 10.