I currently have a Sette Reken built up as my interim bike before I get my new race bike for next year (built it up to get me through the fall and winter after I broke my Kona LeRoi). I just measured the rear clearance with a Maxxis Crossmark UST 2.1 and I have an inch to the bridge between the seatstays and over an inch (1.25-1.5) on the chainstays to the narrowing before the seattube. I also have a 3/4 of an ince on either side on both the chainstays and the seatsays. Would a 650B wheel fit in here? If no one knows is there anyone in the greater Boulder area that possibly has one I could borrow to just put in and see if it fits.

I'm a pro xc racer so I tend to ride only fairly arrow and low profile tires so I would be more interested in the Racing Ralphs or the Quasi-Motos as my tire of choice on this bike. Thanks a lot for all the help!