Disc brake rubbing on new frame

[uad782]

Hi everyone,

Firstly apologies to the guys in the cycle touring section as I have been boring them with this problem.

I recently bought a 2016 Salsa Marrakesh flat bar frame for cycle touring. I am building the bike from scratch. I have sourced some H plus Son wheels (29") from Craftworks who built them with XT hubs. Rear is QR with 6 bolt disc mount.

Like most tourers I prefer cable pull discs so I have bought some TRP Spyke MTB brakes with 180mm rotors. The Marrakesh has an IS mount while the caliper seems to use a PM type mount. I have attached the TRP IS->PM203/180mm adaptor to the rear of the bike. When I install the TRP caliper the innermost pad rubs on the disc. I cannot adjust it out either by moving the caliper or adjusting the pad as per the TRP instructions.

I have tried swapping wheels and calipers (old Magura Louise and Shimano) which still rub. This leads me to believe the problem is either the adaptor or the frame.

I guess the caliper only needs to move half to one mm to stop the rubbing.

Is there some measurement/dimension that I can measure to determine the problem? I think the easiest solution is to add a 0.5mm thick washer/shim between the frame and adaptor. However, this is still clunky as the problem should not exist.

Any comments appreciated.

[Nobody]

Sounds like the frame to me. But if you want to be sure, take it to a bike shop. The washer idea sounds valid. Just keep in mind that QR tension will change the disc horizontal distance too.

Don't play with the pad adjustment screws unless you intend to use a reasonably strong thread locking compound. I've never touched my Spyre ones as I've read they will wander once adjusted. I just adjust the caliper position with the mounting bolts and the pad distance with the cable adjustment. Not ideal, but reliable.

Obviously I'm assuming you've used all the caliper mounting sideways movement available.

[uad782]

Too late regarding the pad adjustment screws. I have used all the caliper mounting adjustment.

[Nate]

Too late regarding the pad adjustment screws. I have used all the caliper mounting adjustment.

I adjusted the pad screws too - no issues this end

[uad782]

I have used all the adjustment to move the closest pad to the rotor out

[Duck!]

Thin washers between the frame tabs and adaptor are fine; it was the standard means of adjustment for IS-mount calipers.