Although most motorcycles in use today use mechanically operated braking means, several have introduced the use of disc brakes. This development is due in part at least to the increased horsepower and consequent higher average speeds at which motorcycles currently operate. These disc brakes, however, have been used only on the front wheels of the cycles. Moreover, these braking systems use a single disc that is located externally and to one side of the wheel hub. Since the plane of the disc brake surface upon which braking forces are applied in such brakes is substantially closer to one end of the hub than the other, there is a tendency for the wheel to pull toward one side upon appliction of braking forces at speed. This pulling creates a potentially dangerous physical imbalance or lateral instability especially at high speeds. Such arrangements also appear to result in torque and loading imbalances that are absorbed by one of the legs of the motorcycle front fork. This torque imbalance includes a component about an axis normal to the axle of the wheel. The loading imbalance includes side forces generated by piston reaction that are transmitted to the leg of the fork. Such difficulties or limitations may have contributed to the limited use of disc brakes to the front wheels of motorcycles. In addition, the disc brakes heretofore in use are rther bulky and cannot fit readily into the rear wheel area which must also accommodate the drive mechanism.
USPTO Backgrounds
USPTO Backgrounds