I built a set of 27.5+ wheels for my wife's gravel touring bike. I tried to save a few bucks by using SLX hubs and rotors with the existing XT calipers. The goal is to be able to switch between the 29 X 2 and 27.5 X 3 inch wheels easily. My LBS assured me there was complete compatibility between XT and SLX drivetrain components. It turns out that the rotor is outboard about a half millimeter. It is not much, but the drag is noticeable. I could shave off a half millimeter from the inside of the rotor hub with emory cloth on a flat surface, but i'm afraid I could introduce a wobble. I could use spacers or modify the locknuts to offset the hub inboard. Does anyone have suggestions for a best practice for a solution for this problem. Thanks in advance.