I had never seen 650b as a MTB wheel size until the above links, so thanks. Has anyone here done a 26" to 650b conversion? I'm wondering how the canti brakes work with the larger wheels. If that could be sorted out, I'm sure I could find an old hardtail-hardnose MTB to convert into a poor man's 29'er (about the only bike missing from my stable.) Might even be worth doing a little brazing to move the studs.