Originally Posted by well biked
Nope, won't work. Even if you went to disc brakes, the stays are too short, along with the fork legs, on mtb's designed for 26" wheels to accept 29ers............And you wouldn't have anywhere near the clearance between the stays, fork legs, etc. on a road bike to accept a true 29" mountain bike tire. Sorry-
I've seen it done. There was pleanty of room for 700c's on a mountain bike frame designed to accept huge knobbies. This bike had road side pulls installed. The only thing I didn't like was that the studs for the cantilevers were still there.
The frame has to be cold set to accept a narrower road hub. but that's no big deal. The special tools required are a 2X4, a piece of string and a ruler.