A disk for a disk brake is formed in two parts: a braking band which cooperates with a brake caliper to generate the braking torque, and a bell connected to a wheel hub and connected to the braking band by a tangential restraint system which provides for a plurality of protuberances of the band, housed in respective seats of the bell.The relative axial positioning between the band and the bell is maintained by a connection element fixed firmly to the bell and urging the protuberance constantly towards an abutment element fixed firmly to the bell and arranged on the opposite side of the bell to the connection element.