Bicycle chain wheel has an oval shape, to give a variable reduction ratio during rotation to optimize the power transmitted to the driving wheel from the pedals

摘要

To increase the drive power of a bicycle or other pedal vehicle, with or without gear selection, the reduction ratio is varied according to the pedal position using an oval chain wheel. When the pedal is pushed in the driving direction, in a downwards movement from the vertical of 0degrees, a higher rotation is transmitted to the driving wheel between the 45degrees and 135degrees positions than the sum of both pedal movements between 0degrees and 45degrees and between 135degrees and 180degrees. The angles are all related to the downwards pedal propulsion movements, without regard to any freewheel.