At a high speed (about 50km/h, but not sure exactly, as I don't have a speedometer) the disc starting to noise like it is touching the caliper/pad. At low speeds It doesn't noise and it's rotating ...
I'm running disc brakes on my cyclocross bike with semi-metallic brake pads. I find that I'm constantly having to keep my rotors cleaned off to ensure optimal performance. I'm used to my mountain ...