Abstract: An infinitely variable forward speed mechanical transmission uses asymmetric helical/spur gear trains mounted to rotate within a rotor assembly to reduce the torque output within the rotor assembly through inefficiency of the asymmetric gear trains. The rotor assembly includes integrated input and output hubs having adjacent radially flush outer control surfaces, with the output hub in mesh with the asymmetric helical/spur gear trains in mesh with an output shaft. A transmission speed control device connected to a control gear connected to a control tang of a wrap spring positioned about the control surfaces of the input and output hubs provides infinitely variable control of the relative rotation of the two hubs to selectively control the torque output of the transmission.