Shimano Disc Brake Adaptors Shimano Disc Brake Adaptors are the finest disc brake adaptors available for Shimano disc brakes. Utilizing an extremely stiff aluminum construction, you will achieve your proper brake alignment and optimum function. This adaptor is for mounting a standard Post Mount caliper to a Post Mount fork to use a 203 mm disc brake rotor. Thisadaptorisdesignedto fit a 203 mm rotoron forks with a 180mmnative brake mountconfiguration (forks that run a 180mm rotor without anadaptor).Use all Shimano brake components for the best braking performance. Lightweight, Stiff Aluminum Construction For Post Mount forks to Post-Mount Calipers and 203mm Rotor Includes Mounting Bolts Brake Caliper Mount: 74mm Post For Rotor Diameter: Front 203 mm Frame/Fork Mount: 74mm Post Mount (180mm native) Caliper Type: 74mm Post Mount | Shimano F203P/Pm Disc Brake Adaptor 203mm Rotor, 74mm Caliper, 180mm Dm Fork