Stage-variation variable speeds transmission bicycle

A stage-variation variable speeds transmission bicycle, comprising a bicycle bracket (1), wherein the bicycle bracket (1) is provided with a medial axis (2), a medial axis chain wheel group (3) is arranged on the medial axis (2), medial axis chain wheel group (3) comprises three chain wheels with different size;

• also comprising a freehub (18) arranged on bicycle rear shaft (16), the freehub (18) is fixed with a sun gear (4), one side of the sun gear (4) is provided with a planetary carrier (5), planetary gears (6) are provided in the planetary carrier (5), a gear ring (7) is provided radially outward of the planetary gears (6), a ratchet (8) is provided radially outward of the gear ring (7), the ratchet (8) is provided with a pawl (9), and the pawl (9) is fixed on the bicycle bracket (1), the pawl (9) is controlled and adjusted by connecting with a derailleur beside bicycle handle by a steel wire rope (13), the pawl (9) and the ratchet (8) are detached or engaged by the extension or retraction of the steel wire rope (13), pin coupling A (10) is provided axially outward of the planetary carrier (5), a main chain wheel (12) is side-by-side arranged beside the planetary carrier (5), one-way bearing (19) is provided inside the main chain wheel (12), the main chain wheel (12) is also provided with pin coupling B (11), the pin coupling A (10) on the planetary carrier (5) and the pin coupling B (11) on the main chain wheel (12) are engaged, thereby the main chain wheel (12) can effectively power planetary transmission (17).