This is a quadaped trike, as opposed to a trike modified into a quad, which has four wheels (and as opposed to a quarduped, which is an animal with four legs.) A quadraped has four cranks, two for feet and two for hands.

The quadraped was originally built by designer Gary Hale for people with disabilities. Each was custom made to the client's specifications. He fabricated one for a triple amputee. Subsequent versions were intended for typically able riders who wanted and upper as well as lower body workout in their trike ride.

When I bought the quadraped, the cranks were all aligned together (left) rather than alternating left and right (below). The first is better for a full body workout; the second for typical cruising.

Steering is accomplished by moving the tiller in the direction of the turn. The tiller also supports the hand cranks.

A direct drive chain connects the hand cranks with the foot cranks, so they always turn in tandem. A second chainring connected to the foot cranks powers a chain to the middle derailleur and five-speed freewheel. A third chain connects an extra sprocket on the center freewheel to another one on the rear wheel.

Both front wheel drum brakes are controlled by a single lever on the left side of the frame. The two shifters are located on the right side of the frame.

One of most common questions about the Quadraped is, doesn't the tiller steering twist the chain?

The answer is yes, but the twist is small where it enters the derailleur and where it exits the cassette.

This picture shows maximum twist, a turn I seldom use even on the windng trails here. The chain rolls across the cassette quietly, and the short cage derailleur moves the chain smoothly.

One quirk of this type of steering is that if you back the tike while turning, one or both chains come off. It is a lesson quickly learned. Keep the wheels straight when backing, or lift the rear wheel off the ground. The reverse is also true, so that reattching a chain on a twisted ring is a snap.