Joe, the bike shop had the same issue when they did the build of our Co-Motion Speedster last summer. We have the exact same setup, the Wound-up fork, Rolf tandem wheels, and avid BB7 disc brakes. The shop contacted Co-Motion about the problem and CoMo sent out a replacement fork. It had exactly the same issue. They ended up milling the aluminum bracket that mounts the caliper to the fork so that it is centered properly over the rotor. It must be a design issue between the Rolf wheel and the Wound-up fork.