Patent ID: 7344468

Claim:
A bicycle crane speed change sprocket module, said speed change sprocket module having a center for pivotally coupling a crank axle, and said crank axle being driven by both ends of a crank to rotate at an external axle pipe; said speed change sprocket module further driving a chain, and said chain being controlled by a front wheel speed change device to switch on two adjacent gears, and said speed change sprocket module comprising: a fixed star gear, having a ratchet at its internal periphery and a center for passing said crank axle, and said fixed star gear being a fixed part not driven to rotate by said crank axle; a plate, having a center pivotally coupled to said crank axle and being a rotary part driven to rotate by said crank axle; at least two planet gears, axially and rotably disposed on one side of said plate, and said planet gears being engaged with a ratchet of said fixed star gear; at least two chain wheels, having a tooth number smaller than that of said two planet gears, and being driven to rotate by said two planet gears, and the rotary speed of said chain wheel is faster than that of said planet gear; and a freewheel sprocket, freely and rotably coupled with said crank axle and being proximate to said two chain wheels, and said freewheel sprocket having a ratchet at its external periphery for engaging said chain onto said two chain wheels, and said chain being engaged with at least one of said chain wheels.