650'b only to out niche anyone on a 29er but IMO its dead in the water. Tyre and rim options are very limited I've no idea why someone would choose it. Either stick with 26 or move up to 29. I think the only manufacturere offering one is Haro with the Beasley.
EDIT:Looks like the Beasley has been dropped.
EDIT:Looks like the Beasley has been dropped.