Well, on one rotation of every rear wheel spin, I hear a noise, but the rotor is never touching the brake pads. That's not what the noise is coming from. I just tend to think with a big mountain bike tire, that some subtle wobble of the disc rotor is more normal than not even on perfectly new compnonents. If you have a mountain bike with a rotor that rotates perfectly straight when carefully inspected, I'd consider that a marvel and would like seeing a video.