Abstract: A continuous, variable power transmission device for use with a crank driven power train wherein crank lever arm movement passes through a prescribed arc of less than 180 degrees in reciprocating sequence applicable to a rotary drive wheel. The device includes a frame, a support arm movably attached to the frame in a manner such that the suport arm may be variably displaced in forward and rearward directions. A rotary drive wheel is attached to the support arm such that the wheel axis is displaced in concert with the support arm movement. At least one crank lever arm is rotationally coupled to the frame, with the remaining end being free to receiprocate through a portion of the defined prescribed arc. A guide track is disposed along the length of the crank lever arm and a tracking member is coupled within the guide track for displacement in reciprocating movement. Coupling structure is attached to enable applied force at the crank lever arm to pass through the tracking guide to the rotary wheel.