Originally Posted by rekmeyata

I'm not sure I understand you. The size of wheel combined with the a fat MTB tire, in your example is 26" which is as tall as a 700x23, but I wasn't talking about those two types of tires, and even if I were the size is the same from the ground to the top of both tires, thus whatever point you're trying to make is moot. The point of having chainring size change would be if you have two wheels, with tires, one would be say 27" and the other say 20" and to get the same speed from a similar performing cyclist riding each bike would require a different gear ring size on the smaller one so he can keep up with the larger wheel/tire cyclist, thus the weight of the larger chainring would off set the weight of the reduced size wheel/tire combo.

My point was the comfort issue more than anything else since I know so little about the other stuff, so I found this to help explain that more than I did: http://sheldonbrown.com/650b.html