Abstract: A exercising apparatus attachment is disclosed as comprising one or more air deflector devices that are adapted to be mounted on the driven rotatable wheel of an operator propelled device, such as the spokes of the wheel(s) of a bicycle, for increasing the resistance to rotation of the wheel and hence provide an exercising function for the vehicle operator. The attachment includes a pair of planar deflector sections interconnected by an intermediate web section arranged generally perpendicular to the plane of the sections and one of the deflector sections includes a plurality of deflector portions that are separated from one another in a radial direction relative to the axis of the wheel to which the deflector is attached.