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  • Shimano - SM-MA90 Disc Brake Adapter - One Color
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  • Shimano - SM-MA90 Disc Brake Adapter - One Color

Shimano SM-MA90 Disc Brake Adapter


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    • One Color, Post, 180mm
    • One Color, Rear ISO, 160mm
    • One Color, Rear ISO, 180mm
    • One Color, Rear ISO, 140mm

    18 Reviews


    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.

    • Item #SHI0547

    Tech Specs

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

    Tech Specs

    • Reviews
    • Q & A

    What do you think about this product?

    Have questions about this product?

    So you went XTR

      We see that, and we respect that. Now, make sure that everything plays nicely together by making sure you use the correct hardware. These not only drop weight, but use a different bolt to match with the XTR calipers.

      Not just for 180

      • Familiarity: I've put it through the wringer

      Got the 180 post mount adapter. Essentially its a 10mm spacer used to increase rotor size by 20mm. Worked great with TRP HYRD to mount 160mm rotors on a Ritchey cross fork. Also used it to swap up from 160 to 180 front rotor on my mtb bike. Does what it needs to do.

      Basic excecution

      • Familiarity: I've put it through the wringer

      It is amazing that a seemingly basic component can be done in so many different ways at different degrees of successful execution. Shimano does theirs very well. keeps the caliper stable and in the correct position with very little, if any flex. You need this adapter for most builds today.

      gotta have it

      • Familiarity: I've used it several times

      My fat bike came with hydraulic 160mm rotors in front and back. For winter, I wanted mechanical brakes and figured I'd upsize the front. Need an adapter to accommodate the 180mm rotor. I used this even though installing TRP Spykes with an centerline rotor--it's all working well together.

      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.