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Whether you're in paradoxical possession of post-mount brake calipers and a flat-mount frame or just need to correct flat-to-flat mount adapter to fit your chosen rotor size, Shimano has a Flat Mount Disc Brake Adapter to get you up and running (and stopping) in a flash. Available in a variety of post/flat and flat/flat combinations to accommodate 140mm and/or 160mm rotors, this adapter installs quickly and ensures your calipers work seamlessly with that shiny new frame.

  • Adapt flat-mount calipers to different mounts and rotor sizes
  • Available in post/flat and flat/flat combinations
  • Options for both 140mm and 160mm rotors
  • Reviews
  • Q & A


    Fit and function were excellent

    Worked as advertised

    • Familiarity: I've put it through the wringer

    Converted my 140mm rear rotor on a BMC Roadmachine 01 to 160mm so I could interchange wheels from several bikes. Easy to install. No worries here.


    • Familiarity: I've used it once or twice and have initial impressions

    If you need to fit post-mount calipers onto a flat-mount frameset, these little adapters are the way to go. The end result might not look as clean as using a flat-mount caliper, but I'm more than happy to make that compromise if it lets me save the few hundred dollars a new brake system would cost.

    Life Saver

    • Familiarity: I've used it once or twice and have initial impressions

    So I just got a new gravel bike and the ENVE Gravel road fork that came on the frame is the new flat mount standard. The SRAM RED Hydraulic disc brake set that I have is a post mount. I really did not want to buy a new caliper for this new standard, admittedly it would have a cleaner look if I used a flat mount caliper, but I really did not want to shell out extra cash. In comes the Shimano flat mount disc brake adapter to the rescue. I picked up the 160mm "Front Post to Flat" adapter and voila! Everything was right in the world again.

    The description indicates that this adapter allows for installing a flat-mount caliper on a post-mount frame. Is this true? If so, which ones would I need for front and rear? "Post to flat" to me would mean you have post calipers you need to install on a flat frame, so I was looking for an item called "flat to post"--but do I have this backwards?

    Thanks in advance.

    Hi, so this mount is for installing a post mount or standard brake caliper onto a flat mount frame.

    Right now there are no adapters that would allow flat mount calipers on post mount frames. The one you mention means adapting a post mount caliper to a flat mount frame. I am glad I called shimano before being really dissapointed once I ordered it.