US Patent 10220911 Drive assembly for a human-powered machine

A drive assembly for a human-powered machine may include a front crankset spaced from a rear crankset, each rotatably coupled to a frame. Crank arms of the rear crankset are longer than crank arms of the front crankset. A left foot platform and a right foot platform each have a rear portion rotatably coupled to a distal end portion of the corresponding rear crank arm, and a front portion in sliding and rotating engagement with a distal end portion of the corresponding front crank arm. The front crankset and the rear crankset may be mechanically coupled to each other, such that the two cranksets turn together at the same rotational speed in terms of RPM. The two cranksets may also be operatively connected to the hub of a wheel.