Offset bicycle pedal mechanism - has guide fingers on pedal arms working in cam grooves and parallelogram linkages

摘要

The bicycle pedal mechanism has at hub level on each side of the frame a component with a groove (13) forming a cam, and accommodating a roller-ended guide finger (15) fixed to the pedal arm. The latter in turn is secured (17) to the pedal wheel by two links (22, 23) and a crank (21) forming a variable parallelogram. The geometrical figure described by the pedal axis during a revolution can be a circle whose centre is offset towards the front of the bicycle from that of the pedal wheel. There can be a stop ring fixed to each grooved component to hold the finger in place. All joints between links, cranks and pedal arms can incorporate ball-bearings.