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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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Unanswered Question

I have a realm beach cruser from the 60s it comes stock with springer forks I would like to put a disc brake on the front is there a adapter that will work on the springer forks for a disc brake. I'm about ready to give up and go for a drum brake. Thanks

Easy to install

  • Familiarity: I've put it through the wringer

I would use these for Sram or shimano brakes. Work the best for either option and they are super easy to install brakes with.

Avg. ride time: 6h 23m 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: 7m 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 - klivingston@backcountry.com - 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