Abstract: An exercise device, for simulating elliptical motion of stair climbing, comprising a frame having a front support and a rear support, and comprising upper and lower exercise units. The front support and rear support meet at an apex where they form an acute angle. The exercise units each comprise a pair of elliptical guide tracks which each form a closed loop. A pair of actuating levers are each attached onto the guide tracks by a partial sleeve which is capable of travel around said loop. Each exercise unit also comprises a flywheel assembly which each has a pair of flywheels mounted to the rear support. Each flywheel is attached to one of the actuating levers by a connecting lever. The flywheels are shaped and the connecting levers are connected to the flywheels so as to permit elliptical motion of the actuating levers around the guide track.