SHIMANO A BRAKES / ADAPTORS R203P/S Adaptor: Go Big Out Back Want more rotor on the rear? This adaptor mounts a post mount caliper to an IS frame and lines it up for a 203mm rotor. Rotor 203mm Position Rear Caliper 74mm Post Mount Frame 51mm IS Why You&';ll Love It More rotor, more stopping. Step up to a 203mm rear rotor. Shimano fit. Built to pair Shimano post mount calipers with IS rear mounts. Ready to bolt on. Mounting hardware comes with it. Compatibility Rear brake with a 203mm rotor Post mount caliper to a 51mm IS frame mount Check your frame&';s brake mount and its maximum rotor size before you order Why buy from Gravity Coalition: we&';re a real Wasatch Back bike and ski shop, not a warehouse. Stop by our Midway or Heber City shops and we&';ll help you get the right part, or order online and we&';ll get it out the door. Questions? Call us at 801-448-6096.