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Item # SHI0108

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  • SM-MA-F160, P/S Front ($5.99)
  • SM-MA-F180, P/P Front ($5.98)
  • SM-MA-F180, P/S Front ($5.99)
  • SM-MA-F203 (160mm to 203mm), P/P Front ($5.99)
  • SM-MA-F203 (160mm to 203mm), P/S Front ($5.99)
  • SM-MA-R160, P/S Rear ($5.99)
  • SM-MA-R180, P/S Rear ($5.99)
  • SM-MA-R203, P/S Rear ($5.99)
  • SM-MA-F180, S/S Front ($6.95)
  • SM-MA-F203 (180mm to 203mm), P/P Front ($7.99)
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Item # SHI0108


Like much of life, making your Shimano disc brakes work with your 160mm rotor is easy --once you learn how to figure out which adapter you need. Whatever you have, we can either sell you the adapters to make it work, or tell you that what you have is enough.

You need to know three things -- what kind of mount your Shimano disc caliper is, International Standard (ISO) or post mount. If it goes on the front, you need to know what your fork is: ISO, post-mount, or a few special cases (Marzocchi 20mm axle, Boxxer-type). And, you need to know the rotor size that you're trying to fit -- in this case, it's 160mm.

If you're trying to diagnose what you already have and/or what you need, here's how to do it. The Shimano adapters all have a model number that starts with SM. The Mount Adapter acronym is MA. Front brake is F. Rear brake is R. Rotor Size is 160, 180, or 203. Caliper Mount Type will be S for ISO/International A, and P will represent Post. And the last letter will be for the frame or fork mount type: S for ISO/A, P for Post, B for Boxxer, Z for Marzocchi 20mm Axle as well as QR20Plus and DH ISO. Thus an adapter that reads SM-MA-F-203S/P is Shimano Small Parts Mount Adapter Front 203mm Rotor with ISO caliper on a Post type fork.

  • Durable alloy construction
  • Mounting hardware included
  • Compatible with ISO and post-mount calipers and frames/forks

Tech Specs

Recommended Use:
Stopping your bike

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Avg. ride time: 6h 35m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Gotta Have It

  • Familiarity: I've put it through the wringer

Cracking the Shimano-speak code to figure out which one you need is the hardest part. Once you have the right one, it's easy to install, and does what it needs to do. Never had an issue with any of these that I've used.

Avg. ride time: 20m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Great Adapter

  • Familiarity: I've put it through the wringer

This is a great adapter for disc brakes. Find which one you need and get it. These adapters keep your caliper where you need it with little flex.

Better Choice than Avids

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

I originally got the Avid Post Mount Brake Adapters (Item #AVI000D) for my new SRAM Guide RSC Disc Brakes but swapped them for these Shimano Disc Brake Adapters. Much better choice and cleaner look on my bike, no extra washers or spacers required.

Big thanks to Joe Bolton in our Retail Store Bike Shop for getting my new Mach 6 put together. If you are ever in Salt Lake City definitely stop by our Retail Store to check out their bike selection and visit Joe (2607 S 3200 W, Suite A, West Valley UT 84119). Contact me with any questions about these adapters, especially if you are interested in custom building a new mountain bike.

Kyle L. - Expert Gearhead - - 801-736-4337

Frame - Pivot Mach 6, Large Stealth Black/Green

Brakes - SRAM Guide RSC Disc Brake - Black Ano, 180mm front/180mm rear

Adapters - Shimano SM-MA-F180, P/P Front

Better Choice than Avids

Needed for bigger rotors

  • Familiarity: I've put it through the wringer

I recently went from a fork with 200mm posts, to a 180mm post, and needed to get an adapter. Installation is as simple as installing a caliper right to the post, but the extra spacing allows for larger rotors.

Shimano upgrade for trial bike

  • Familiarity: I've used it several times

Used the MA-F180P/S to upgrade the terrible front brake on my newly acquired trial bike. It came stock with a 180 rotor and IS mount caliper. This bracket placed my new XT caliper right into place. Very easy to install, and the extra description provided by Backcountry helped ease my mind that I chose the right part the first time. True thanks to them for the great explanation!

Solution for the 2015 Fox Float +203mm

  • Familiarity: I've put it through the wringer

Finally, a perfect solution when you have the 2015+ Fox Float fork and want to mount a 203mm front rotor. Much better than using a 180mm spacer + washers

Factory Equipment

    What else would you use for Shimano Brakes? I decided to upgrade my front brakes from a 160 mm disc to a 180 mm. This part is necessary for that upgrade, moving the brake calipers 20 mm further from the hub to accommodate the larger disc. Works like a charm

    Road Disc Adapter for 140MM to 160MM

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

    Its a small package from Shimano, all of the proper fittings are included.
    There is a bit of confusion at the moment if you are installing a 160MM rotor on a disc equipped road bike. If you are stepping from a 140MM to a 160MM on your road fork, this is the most likely the part you need. Its simply a 20MM step that mounts inline post -to post on your fork, works if you are originating from a 140MM or 160MM. I used this with a Shimano RS785S setup and an ICE centerlock rotor. Works like a charm, no hassle.

    Road Disc  Adapter for 140MM to 160MM

    Sorry, didn't see this until recently. For those mounting post to post (99.999% of the new road bike disc market) the part number is:
    Shimano Disc Brake Adapters
    SM-MA-F180, P/P Front
    Price: $8.06

    Thanks for the post. Any idea of this will also work for a rear brake. My Fuji CX is currently meant for 140mm rotors. Just curious if this adapter (SM-MA-F180, P/P Front) will also for the rear to make it work with a 160mm rotor. Thanks!

    Hi Peter , its works on both front and rear brakes for stepping from 140MM to 160MM. I have successfully used them on both Shimano hydraulic and non-hydraulic disc calipers. Its confusing because the part number is the same for front and rear, when mounting post to post with a 20MM step.

    Avg. ride time: 3h 47m per week
    • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

    Slow your roll

      I always upsize my rotors to 180, front and rear. These will get the job done.

      Unanswered Question

      I have a 2011 Specialized Stumpjumper 29er HT with RockShox Reba RL 29, 9mm-travel w/lockout (15.5": 80mm travel and I am hoping to install the Shimano XT SM-RT86 6-Bolt Disc Brake Rotor (180mm) on the front. I do not know which mounting bracket I need? Can you please help me? I really appreciate it.
      Thank You.

      Austin Blasingame

      Unanswered Question

      I have a Mach 5.7 pivot with fox float fit Tlc up front what brake adapters would I need to go to 160 in back and 180 up front