Abstract: Leg-powered, foot-steerable devices for attachment to a wheelchair are disclosed that include a longitudinal pole unit, attachment clamps for releasably mounting the pole unit upon the frame of the wheelchair and a wheel assembly that includes a bearing unit carried by the pole unit, a pillar assembly carried by the bearing unit for limited rotation about a steering axis, an axle supported by the pillar assembly, at least one drive wheel carried by the axle for free rotation thereon and for limited rotation with the pillar assembly about the steering axis, and a pair of peddles fixed by opposed crank arms on opposite sides of the drive wheel for simultaneous rotation thereof by the feet of the wheelchair user about the steering axis and the axle.