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Item # SHI0108

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  • Select options
  • SM-MA-F160, IS/Post Front ($8.99)
  • SM-MA-F180, Post/Post Front/Rear ($5.98)
  • SM-MA-F180, IS/Post Front ($8.99)
  • SM-MA-F203 (160mm to 203mm), Post/Post Front/Rear ($8.99)
  • SM-MA-F203 (160mm to 203mm), IS/Post Front ($8.99)
  • SM-MA-R160, IS/Post Rear ($8.99)
  • SM-MA-R180, IS/Post Rear ($8.99)
  • SM-MA-R203, IS/Post Rear ($8.99)
  • SM-MA-F180, IS/IS Front ($6.95)
  • SM-MA-F203 (180mm to 203mm), Post/Post Front/Rear ($7.99)
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Item # SHI0108


Whether you're trying to mount your 160mm rotor with an ISO or post-mount setup, we've got the right Shimano Disc Brake Adapters for the job. All you need is the skeleton key to understanding Shimano's admittedly byzantine model naming convention. SM-MA stands for Shimano Mount Adapter, so that'll be universal across models and can be safely ignored now that you're here.

The rest of the model name is the important part. An "F" denotes front brake and an "R" denotes rear brake. The following number (160, 180, or 203) is, of course, the rotor size, with special parentheticals for 203mm rotor conversion. The final two initials respectively describe the caliper type and the frame/fork mount type with either a "P" (post-mount) or an "S" (ISO). To alleviate confusion, we've reiterated the front or rear specification at the back.

To recap, model number SM-MA-F160, P/S Front is for the front brake (F), it accommodates a 160mm rotor (160), it holds a post-mount caliper (P), and it attaches to an ISO fork mount (/S).

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

Tech Specs

Recommended Use:
Stopping your bike

Reviews & Community


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Choose the Right

  • Familiarity: I've used it several times

Necessary part for bikes with rotors 140 plus. Just make sure you select the correct model and don't trust our photos to be the exact sub-model. Feel free to call us with any questions at 1-888-276-7130 for parts questions.

Fox 36 YES

  • Familiarity: I've put it through the wringer

Finally, a cheap solution to mounting my 203mm rotor to my Fox 36 perfectly. Couldn't believe Fox wanted $35 for the 180mm to 203mm P/P adapter. I love their stuff but come on. Shimano for the win

Helps in slowing down.

  • Familiarity: I've used it several times

Changed a rotor and needed this to make things work. Easy install and now I'm good to go. Or stop... Whatever...

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: 4h 43m 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: 36m 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!