I'm gonna fix up a monocog 29er, but I'm building it up from the frame. The 110mm spacing isn't too bad of a problem if you're willing to build up a wheel with some track hubs that can be respaced. My Promax SBs have washers that can be removed to givea 110mm spacing. The only problem would be making sure the hubs were dirt-worthy. I wanted to run a disc rear on a fixed hub, and one nice solution are atomlab's Disk Adapters. The six bolt mount just threads onto the freewheel thread, and there's a caliper mount for your frame if it wasn't equipped with tabs.