MTB Disc Brake Adapters

Adapters between the mount on the frame or fork and the brake caliper. They let you run a larger rotor than the mount alone allows. Three things decide which adapter fits: the mount on the bike (IS or post mount), the rotor size you want and whether it sits at the front or the rear. On IS mounts the maths differs between Shimano and Avid, so the brake maker is always stated.