My gut tells me that the "limited availability" critique of 650B is overplayed. Having ridden a few short (4-7 day) tours, I feel that such wheel/tire failure is too rare to warrant sustained consideration. I'm planning a cross-America on 650bs, and think that I'll bring a spare tire in case of blow out (which, with newish tires, seems unlikely). But the risk of wheel failure seems overstated. Given the fat tires, smaller wheel size, and assymetrical rear rim, failure seems unlikely on my 650Bs. But having never toured for extended periods, I'm looking for the experienced folks' opinions.
Now, I understand that wheel size provokes some of the hottest debates in the bike community. Pundits on any side of the wheel debate -- 26", 650A, 650B, 700C, 27" -- can and will extol the virtues of their particular wheel size while eviscerating all other wheel sizes' inability to offer "the perfect ride." A search through the forums will turn up myriad opinions on this tired debate (yes, pun intended). So in this thread, let's avoid posts lauding the intrinsic virtue of any wheel size.
My question relates only to experience. I want to put my gut feeling about the improbability of wheel failure on public display. Are there any long-distance tourists who have ridden across the United States on 650Bs? Did you actually encounter any of the dreaded tire blow-outs, rim collapses, or other hypothetical problems associated with 650B's limited availability? Did you have trouble finding whatever replacement part you needed?
And likewise, to experienced long-distance folks of all tire sizes (especially those who have ridden cross-country): how frequently have you had serious tire/rim/wheel failures? If you had such failures, did faulty materials (a poorly built wheel; an old and deteriorating tire; a too-low spoke count; a cheap or inappropriate rim) cause your plight? Or were they the kind of catastrophic and unpredictable failures that cause tourists to lose sleep?