A U brake uses studs (bosses) attached to the front fork or frame above the rim, rather than below it, as with conventional cantilevers. U brakes use the same type and placement of studs as roller-cam brakes do. In 1986-88 there was a fad for equipping mountain bikes with U brakes...
serious risk. If the main cable of a traditional cantilever brake fails, the transverse cable can snag on a knobby tire and lock the wheel. If the front wheel, the rider will pitch forward. A direct-pull brake only stops working if the cable parts. Your bicycle has two brakes -- right...