Abstract: A brake disk includes a central hole so as to be connected to a wheel shaft and a serrated periphery which includes a plurality of first protrusions and a second protrusion is located between any two adjacent first protrusions. Two recesses are connected between the second protrusion and the two adjacent first protrusions. A plurality of first grooves and second grooves are defined in each of two sides of the brake disk. Each second groove communicates with the first groove corresponding thereto so that rain drops, dust and debris from lining plates of calipers can be easily removed from the brake disk.

Abstract: A brake disk has a disk body. The disk body has two sides, an outer periphery, a central hole, multiple through holes and multiple curved grooves. The central hole is defined through the disk body. The through holes are defined through the disk body around the central hole. The curved grooves are defined respectively in the sides of the disk body and each groove has a first end extending to the outer periphery of the disk body and a second end extending to and communicating with one of the through holes.