Wow, this thread really took on a life of it's own! 29" wheels just look too goofy to me in larger diameters on a serious off-road bike, they're so big unless you have a XL frame. I could see the potential of 650b in that application (though I did ride a Haro Beasley 650b with 2.3 Nevegals for 6 months or so, and switched back to 26" on the next build...)