An exercise machine includes a frame, a first rotary mechanism supported on the frame, a second rotary mechanism rotatably engaging with the first rotary mechanism, and a driving mechanism operatively coupled to the second rotary mechanism and configured to impart rotation of the second rotary mechanism while the driving mechanism is being actuated. The second rotary mechanism is hubless. The second rotary mechanism is configured to absorb and retain an amount of the actuation of the driving mechanism as a moment of inertia while the second rotary mechanism rotates.