A bicycle brake unit includes a first arm, a second arm and a connector, when the brake cable is pulled, the first and second cable connectors on the two arms are moved toward each other to pivot the first and second arms. The first rail on the first arm and the second rail on the second arm are moved relative to each other via the rotation of the pivot. The pivot is movable in the elongate slot in the connector which is pivotably connected to the first and second arms. The first and second arms are pivoted toward each other to brake the wheel by the brake pads on the two arms. The first and second arms apply even forces to the two brake pads.