Is there much difference between 26" and 650b? I think in terms of size they're pretty close, although tire selection maybe is what you're going for. I have Panaracer Urban Max tires on my Stumpjumper. They take 95 lbs. and ride great. Maybe a bit narrow for what you have in mind, though. They're 26 x 1.25". [edit] OK, 650b is 584 ISO and 26" is 559, so I guess that's more of a difference than I thought.