I'm thinking about building up a new single speed, and I'm kicking around the idea of trying 650b wheels. It will be a XC oriented hard tail. Is it a good idea to get a frame intended to run 26's that fits 650's or a dedicated 650b frame? I like the idea of changing back to 26 if I don't like the 650b, but I'm afraid the geometry might be weird with the bigger wheels. Does anybody have experience with a 650b single speed and want to share some thoughts?