Importance

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Abstract

A variable ratio bicycle drive mechanism has particular advantages for use in the drive train of an off-road bicycle but has application in human powered vehicles generally. The mechanism provides a mechanical advantage which varies with the position of the pedals. The angle between the left and right pedals is not fixed at 180.degree. but varies as the pedals rotate so that one pedal enters the most efficient part of its cycle before the other pedal has finished the most efficient pad of its cycle. The mechanism can help to improve the balance of a rider and even out the delivery of power by the rider to the bicycle. The mechanism has a driving axle rotatably mounted in a frame and a pair of pedal axles, one for each foot, mounted parallel to and spaced apart from the driving axle. The pedal axles are driven by the rider by means of linkages, which may be conventional pedals mounted at the ends of crank arms connected to the outer ends of the pedal axles. The pedal axles are each connected to the driving axle by means of an arm which extends radially away from the driving axle, an arm extending radially away from the driven axle, and a connecting link having one end pivotally connected each arm. In an alternative embodiment of the invention, the arms connected to the driving axle are telescopic and no connecting links are required.

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First Claim