Abstract: A portable enclosure for the rider of a wheeled vehicle, such as a bicycle, includes an outer skin having an aerodynamically streamlined shape and enclosing at least the torso of the cyclist. The outer skin is supported on the body of the cyclist by a plurality of inflatable cells formed by an inner skin bonded at selected points to an inner surface of the outer skin. The two skins are shaped and assembled together to define an access opening in the bottom of the enclosure through which the cyclist can insert his torso into the enclosure. An opening may also be provided near the top and front of the enclosure, through which the cyclist can project his head. Alternatively, a similarly located socket may be formed in the enclosure to receive and gimbal a rigid protective helmet worn by the cyclist and having a rounded outer surface.