211,725. Bourgard, P. March 15, 1923. Back-pedalling brake and free-wheel arrangements.-In a coaster hub for bicycles, a triangular or equivalently screw-threaded driving-sleeve 2 engages with a correspondingly threaded nut or sleeve 5 which is longitudinally slotted, as at 5<1>, for the greater part of its length, the slots starting alternativelv from one end and then the other. During driving the coned surface at the left-hand end of the nut engages with a corresponding surface on the inside of the hub, but on backpedalling, the teeth of a ring 6, coupled to the nut, engage teeth on an anchored bearing-cone 7 so that the nut is expanded into contact with the hub. The ring 6 is fitted into a conical recess at the left-hand end of the nut which is flanged at 5<11> to ensure that the ring will move longitudinally with the nut; the ring also has radial lugs engaging with the enlarged ends of the slots 5<1> at the left-hand end of the nut, and in this waythe nut and ring are connected together, for rotational movements. The ring is mounted on a slidable but non-rotatable sleeve 10 which carries a drag spring 11.