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Just fitting a set of Guide RS brakes to my mates bike and having a problem with the front one.
Its on the same Shimano mount his old brakes came off but when tightened up the wheel barely spins at all as it seems the disc is catching the inner caliper. I initially thought it needed aligning and when I loosen the two allen bolts it does spin freely its just once nipped up its almost solid.
Has anyone had a similar problem?
Its asif I need to put a small shim in front of the mount but I know I shouldn't have to be doing that.
Have you taken pads out (don't apply brake! ) and then refitted to see if it's actually fouling the caliper body itself?
Once you've checked what Poopscoop said try loosening both bolts slightly pull the brake leaver and hold it with some elastic bands or get your mate to hold it. Then tighten the bolts up. See if it's still catching once you release the brake leaver. It might just be the alignment is a little off.
I've had issues with some calliper/disc combos.
Specifically hope discs with Shinano calipers. I just put a thin washer under the calliper before mounting to the frame.
Had this a few times with frames that had the mounts faced. The tolerancing of the cast caliper housings do vary quite a bit so you may find one is fine and the other fouls the disc.
Solution as above. I just made some thin washers with some tin snips and a drill.
Thanks guys. I will get some washers later and see if putting one between the caliper and mount helps.
I had the exact same problem last night with a Hope rotor and an XT caliper.
it's most likely a 200mm mount vs 203mm rotor (or 180/183 etc) so the caliper is 1.5mm too close to the hub and is catching the rotor. A couple of shims should sort it out as mentioned above.
Why we have a situation where there are both metric (140/160/18/200) and imperial (183/203) rotors I have no idea but that's "standards" for you 🙄