Shimano XTR Disc Brake Adaptors Shimano XTR Disc Brake Adaptors are the finest disc brake adaptors available for Shimano disc brakes. Utilizing an extremely stiff aluminum construction with a machined-out section in the center, you will achieve your proper brake alignment with a bit of weight savings and a sweet look. Use only genuine Shimano brake components for the best braking performance. Lightweight, Stiff Aluminum Construction For IS (International Standard) 51mm mount frames and forks to Post-Mount Calipers Includes lightweight mounting bolts and bolt safety wire | Shimano | Xtr Is Disc Brake Adaptor Sm-Ma90-R160P/s For Rear 160Mm Rotor