29" is the same as 700c, right? then clearance won't be a problem. i've used the
standard bob with 700x38 and 26x2, both setups with zefal fenders. only
clearance issue you might have is hub width, but these can be used with tandems
with the longer skewer.
never had trouble with xt deraillers. might be an issue depending on the bracket
location in relation to the axle.