Motorized bicycle

In a motorized bicycle having a pedal crank shaft housing, a pedal crank shaft journaled in said housing and pedal cranks extending from said pedal crank shaft, the improvement comprising a pedal crank shaft engagement assembly comprising a slot disposed in said pedal cranks adjacent said pedal crank shaft, a movable pin disposed in said slot, a corresponding slot disposed in said pedal crank shaft for reception of said pin and means for moving said pin into engagement with said slot on said pedal crank shaft whereby said pedal cranks transmit movement to said pedal crank shaft.

In combination with a bicycle having a pedal crank shaft housing, a pedal crank shaft journaled in said housing, a frame having a front diagonal bar, an upwardly extending bar forming a seat support, a rearwardly extending fork, a forwardly extending fork, a wheel carried by said forward fork, a rear wheel carried by said rear fork and a sprocket assembly on the rear wheel, a motor unit attached to said bicycle frame, power input means for transmitting power output from said motor to said pedal crank shaft, a sprocket assembly mounted on said pedal crank shaft, a chain connecting said sprocket assembly with said rear wheel sprocket assembly, and pedal cranks extending from said pedal crank shaft, the improvement comprising means for engaging said pedal cranks to impart movement to said pedal crank shaft and to disengage said pedal crank when power is transmitted from said motor to said pedal crank shaft and comprising a cam surface disposed on the pedal crank shaft adjacent the ends of said pedal cranks, a slot disposed in said pedal cranks, a movable pin disposed in said slot, a tension spring disposed in said slot for urging said pin into engagement with said cam surface, said cam surface having a portion of its surface arranged to engage said pin during operation of said pedal cranks whereby said pedal cranks transmit movement to said pedal crank shaft.