Since 2019, virtually every disc brake road, gravel and cyclocross frameset from a major manufacturer has been built with the Flat Mount disc brake standard. This system allows the disc caliper to sit as close as possible to the frame. Many frames and forks and calipers are built spaced for 140mm caliper/disc rotor use, which is the smallest size option, so to use a 160mm rotor, you must use a flat adapter that gives you the required rotor clearance. The Shimano SM-MA-R160D/D is the adapter you need to increase the clearance for the rear Flat Mount frame interface for a rear Flat Mount disc brake caliper. It was designed by and for Shimano calipers, but works with others as well.

The adapter is precision machined to exacting tolerances for consistent and proper interfacing with caliper and frame. Shimano includes the special steel tapered head-shaft bolts that allow you to secure the mount, plus retaining safety clip. Again, this a rear only adapter for using a 160mm rotor with a Flat Mount caliper designed for 140mm use, on a Flat Mount equipped disc brake frame.