US Patent 8998776 Load wheel for a self-propelled exercise device

A rotational bearing has an outer surface and an outer layer attached to the outer surface of the bearing by overmolding, bonding or mechanical fasteners. The outer layer has an outer surface which rotatably engages a bearing surface of a track along which the bearing device is adapted to travel, and is of a material softer than the material of the track bearing surface, such as a polymer or a relatively soft metal. In one example, the bearing is rotatably attached to a foot link carrying a foot engaging platform of a human powered conveyance or exercise system.