An apparatus for coupling a bicycle disc brake rotor to a bicycle wheel hub is disclosed. The apparatus includes an adapter and a rotor retaining member. The adapter is adapted to be nonrotatably coupled to the bicycle wheel hub and to be nonrotatably coupled to the disc brake rotor. The adapter includes a plurality of axially extending protruding portions adapted to extend through the disc brake rotor to nonrotatably couple the disc brake rotor to the adapter. At least one of the protruding portions has a groove defined therein. A portion of the rotor retaining member is received in the groove in the protruding portion.