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Item # SHI0547

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  • One Color, Post, 180mm ($12.99)
  • One Color, Rear ISO, 160mm ($11.99)
  • One Color, Rear ISO, 180mm ($11.99)
  • One Color, Rear ISO, 140mm ($11.99)
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Item # SHI0547


With the SM-MA90 Disc Brake Adapter, Shimano has taken an artful leap at the lowly disc brake adapter. Not only is it lighter than their older adapters, but it's more refined -- this refinement being the reason for its lightness. Where Shimano's older adapters were blocky, this one has curved edges. Where they were solid, this one has a window machined out of the center of the adapter body.

The Shimano SM-MA90 Disc Brake Adapter is available in five versions to fit 160 and 180mm rotors for front ISO or Post mounts and rear ISO mounts.

Tech Specs

Shimano front ISO/Post and rear ISO
Recommended Use:
getting calipers to fit correctly
Manufacturer Warranty:
1 year

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Here's what others have to say...

Unanswered Question

I have a 140 post mount rear and I want to use a 160 disc rotor, which adapter do I choose?

Avg. ride time: 2h 44m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

180s 4eva

  • Familiarity:I've put it through the wringer

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

What is the Thin Metal Wire used for, that is included?

Responded on

you put it through the holes in the head of your bolts to keep them from coming lose


just works

  • Familiarity:I've put it through the wringer

used these to bring the rear up to 140 and front up to 160 on a specialized xc rig with xtr trail brakes


Upgrade to 180

    I recently installed new rotors on my Santa Cruz Tallboy LTC. After riding a friends bike which had 180mm rotors front and rear, I decided I'd do the same. It's made a noticeable difference for sure. I got the Post for the front and the ISO option for the rear. Just a heads up sometimes ISO is referred to as IS.


    Fits Avid brakes

    • Familiarity:I've put it through the wringer

    Bought this to install a Avid Elixir 9 Trail front caliper on a post to post mount using a 180 Rotor. Fits perfectly! Avid for some strange reason does not sell a 180mm adapter, but only provides them on complete bikes.

    Will this adapter work with shimano xt...

    Will this adapter work with shimano xt brakes on a Fox float RL fork (with post mount). Trying to put on a 180mm rotor but want to make sure i get the right adapter. Thanks.

    Responded on

    The Post 180 mount will work no problem.