Abstract: A sprag wheel is a one-wheeled recreational vehicle. Two treads extending on opposite sides of a ground wheel provide a place for the rider to stand. A flywheel concentrically mounted with the treads and ground wheel and housed within the ground wheel provides pitch stability for the rider. That is, the flywheel is coupled to the treads and ground wheel so that the flywheel rotates faster than the ground wheel. The treads are coupled to the flywheel so that the treads will move only by changing the rpm of the flywheel. Thus, a relatively large force is required to move the treads, and, in any event, a force greater than that necessary for the rider to balance on the treads. The sprag wheel of this invention is designed to imitate Thor's wheel in the "B.C." comic strip, so the ground wheel has a relatively large diameter and a moderate width so that a rider may balance on the wheel.