180mm with XT Caliper on Boxxer

[Christina L]

I've had two different bike shops get me the wrong brake mount. I know that I have a 74 mm post mount on my fork. I know that I have 74 mm calipers. I know that I'm using a 180 mm rotor. Found this picture to show the second bike shop and it still did not help. This is the only thing stopping me from riding my brand-new bike for the last three weeks.





Looking to order this from Universal cycles

Shimano Disc Brake Adapters
180mm / 74mm / Front / 74mm Post / ISMMAF180PPA

Item #: 18669-73890
Mfg#: ESMMAF180PP2
UPC: 689228295841
EAN: 689228295841
Other #s:
BR8593
SH65582
86200812

[StuLax18]

Can you take it into a shop and have them try out different mounts? My 203mm Avid brakes needed a 160mm labeled adapter to work on my Fox 40. We just kept trying until one worked.

[jmallory]

What year Boxxer is it? Please correct me if I'm wrong, but I think a Boxxer is meant to be run with a 203mm rotor, don't think you can run smaller. If its pre-2010 it needs a special adapter, new Boxxers use a normal post mount to post mount.

[Christina L]

it is a 2011 Boxxer. I was only using the smaller rotor because I already had the same size being used on my other bike. That and I only weigh 120 pounds.

[jmallory]

Have you tried just mounting the caliper to the fork? I have a 2013 and I needed an adapter to go to 203 so maybe it is designed around a 180 rotor.

[Christina L]

yeah, definitely needs an adapter.

[lobster_CT]

With the adapters you've purchased, is the caliper sitting too far away from the rotor, or is the rotor "too deep" in the caliper?

If its the case it is too deep, could you put a couple spacers (washers from the hardware store) under the adapter to move the caliper out further until it is in the proper position? That might at least give you "working" measurements you could compare to the measurements of a potential replacement adapter.


Being relatively heavy, I experimented with a 9" rotor on my bike for a period. Even with the specified adapter, it didn't work until I put a couple spacers underneath. The little burled rings from a couple of presta tubes worked perfectly. I just drilled them out so the threads didn't interact with the threads of the caliper's mounting bolts.

[Christina L]

.......