Originally Posted by
pablosnazzy
29" mountain bike wheels are the same size as a road bike wheel (700cc).
The rims are the same size - 622 ETRTO, but the overall diameter of the combined rim and tire are very different. A 700c X 23 road tire mounted on a 700c rim is almost identical to the diameter of a 26 X 2.1 MTB wheel/tire (about 26.4").
A "29er" 2.1 tire on a 700c rim measures about 28.5" in diameter.