I have bolted the rotor to the rear wheel hub and the caliper mount to the chainstay , however...

when I fit the wheel in the dropouts, there is no space between the rotor and the mount. The wheel won't spin freely.

I can't find a solution yet. Am I using a mount of the wrong width? I haven't attached the caliper yet.

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    If the wheel did not originally have a disk likely it was put together with the wheel fully dished to one side rather than being more centered. You likely need to move some spacers to the other side of the axle, then re-true your wheel. It may be necessary to change out some of the spokes. Nov 19, 2017 at 22:58
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    Was your bike's frame built with disk brake mounts from new or did you fit some kind of adapter? Could be your bike just wasn't built for bolt-on disk brakes. Possibly try the seat stay but they're even thinner than chainstays normally. A photo would help a lot, please consider adding one.
    – Criggie
    Nov 20, 2017 at 0:30
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    Can you post a picture showing the mount interfering with the rotor? Nov 22, 2017 at 14:16
  • No camera available at present. I spoke to a technician at the workshop and his only suggestion was that the original (missing) caliper frame adapter that was supplied with the bicycle new was a custom width, thinner than the standard. Have had a look on-line and they all seem to be a standard thickness so am wondering if my only option will be to grind down the metal where it makes contact with the rotor. Unless anyone knows of any narrow gauge brake adapters?
    – andersj
    Nov 23, 2017 at 11:50
  • This will be a tough one to answer without seeing some good pictures of where the interference is. All I can suggest is that most disc brake calipers have slotted bolt holes that allow a good amount of sideways adjustability- perhaps you could simply push the brake caliper out of the way? Feb 28, 2018 at 6:10

1 Answer 1


I have a 2010 Gary Fisher that Trek recently warrantied. They provided me with the entire rear triangle of a 2013 Superfly, which by all appearances seems identical to my old triangle. There are differences though. Most notably with the new drop-outs. They are deeper than the original. By just enough that I was also having your exact problem. The fix - recommended by the mechanic at my local bike shop - was a simple, external star lock washer placed in between the axle end cap and the drop-out.

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