Abstract

The present invention relates to a crank set, for example for propelling a bicycle or driving a similar pedal powered machine or vehicle. A crank set comprises a left and right crank arm. Each crank arm has a piston- in-cylinder whose stroke reciprocates to lengthen or shorten the respective crank arm, thereby enabling a torque, applied to a pedal connected to an end of each crank arm, to be varied. A fluid pathway connects the two pistons via a flow control valve, whereby in use fluid urges a piston to lengthen a first crank arm, during part of its downwards stroke, and to shorten the length of a second crank arm, during part of its upwards stroke. An advantage of the flow control valve is that it enables a user to optimise crank length depending on the terrain or slope.

IPC Classes  ?

• B62M 3/02 - Construction of cranks operated by hand or foot of adjustable length