Pedal crank with varying radius - uses unequal length parallel lever arms on fixed axles to mount pedal pin and inner arm slides in tubular axle crank

摘要

The crank shaft may transmit pedal torque to a bicycle chain wheel axle (A), using crank arms (C,D,C',D') of which the effective length varies during a chain wheel revolution. The arrangement gives a maximum arm length during the drive stroke, and the crank arms comprise lever arms (D,D') which slide axially in a tubular radial axle (A) of cranks (C,C'). Other fixed length crank arms (E,E') connect the crank pins or pedal axles (F,F') to fixed axles (B,B'). The pedals (F,F'), orbit about axles (B,B') while the arms (D,D') slide relative to the cranks (C,C') and the cranks may contain roller bearings which promite the sliding.