Which disc brake adapter?

I picked up a Nimbus 29, which obviously has standard disc mounts. I picked up a IS to Post Mount 160mm front brake adapter from my LBS, but it does not seem to fit correctly.
Is there a specific mount that is needed? Would anyone have a link to the correct mount?
Thanks for the help, picture of the mount I attempted to use is below.

Looks like the correct bracket.
The obvious sanity check questions:

  1. Are you 100% sure that the disk you are using is 160mm?
  2. If yes, what brake are you using? (should be the correct adapter for pretty much most disk brakes currently on the market, but still a safety check)
  3. Are you sure you have mounted everything the right way around?

Every brake manufacturer has their own version of these adapters, which for the most part are interchangeable, but in rarer cases there may be some clearance/fit to the brake disk issues. If none of the suggestions above turn out to be the issue, that may be the problem.

Rotor is a 160mm, not much way for me to mess up installing it.

The brake is a Shimano M365, pretty basic brake.

I tried with the arrow pointing up and the arrow pointing down on the adapter, and there’s just not enough clearance for the caliper to clear the IS mount on the frame it seems. It looks like I would need 5-10mm of spacers to get it aligned correctly.

The install should looked something like this:

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The disk adapters fit a different size front or back of a bike. With your clearance issue, you may try to go for the next adapter size. However, if the caliper would be well aligned on the disk if it weren’t for this clearance issue, maybe it is a problem of shape of the adapter (Nimbus frame should be compatible with 160mm and bigger disks right?).

The standoffs on the adaptor just don’t appear to be tall enough to get the caliper mounts above the IS mounts on the frame. Hard to explain but you can see from the pictures the adaptor isn’t quite correct. A 180 adapter would be much too large.

I will swing by a few local shops and see if anyone has an adapter with a different profile.

That’s weird, I hadn’t heard from any clearance issues with Nimbus frames so far. I hope a different profile adapter can solve the issue! (If not, going to 180mm disk probably would)

(Also, I’ll tag @rogeratunicycledotcom so he can see this and maybe help out)

Possibly 160mm rotors are not compatible? I have a 180mm rotor, but would need to go find a new adapter but that would most certainly fix the clearance issue.
Just a bit of a pain to pull the bearing again to swap a rotor out.

I have a set of mt7 and Mt5 brakes I could throw on but If this m365 caliper won’t clear I don’t anticipate a 4pot brake being any better.

The IS mount on the frames will fit all sizes of brake from 160 up to 210 using a front IS to Post mount.

I suspect that you are trying to use a rear IS mount, they have a different geometry and wont work.

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Is that a cheap non branded adaptor? I have found its best to use genuine shimano ones as they fit better and are only a small cost more.

It is a front adapter, atleast it does say F, which typically means front. I went back into a shop and we dug through some adapters and the few 160f IS TO PM adapters all looked similar.
I ended up just grabbing a 180 and it went together just fine, no issues.

The adapter was just a random shop part, could have been an obscure brand with unique sizing but there are no marks to indicate who made it.

Thanks for the help everyone.


Thats great you got it sorted :+1:

I should probably clarify that I put on a IS-PM 180 adaptor and 180mm rotor.

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