The problem with this is that it is for a given pressure. I'm not going to pump my 700X38's to 100 psi like I would with my 700X28's, so naturally, they would drag more. By the same token, if I kept my 28's at 55-60 psi like I do with the 38's, they'd be half flat, and wouldn't be any faster. The problem being that the larger the tire, typically the lower the pressure.


Also, you're talking about weights as well. I could have my 600 gram 38's, or I could have my 350 gram 28's. What is the weight theory? Adding 1 lb of reciprocating mass is like adding 5 lbs to the frame?

Something like that anyway.

As always, bless Sheldon:

A common debate among cyclists centers on the issue of whether a wider tire has more or less rolling resistance at the same pressure. The constant pressure is proposed because it appears more scientific to eliminate this as a variable, but this is not realistic in practice. The short answer to this question is that, yes, a wider tire of similar construction will have lower rolling resistance than a narrower one at the same pressure. This fact is, however, of no practical value. If you are comparing two tires of similar construction, with the same load, and the same pressure, either the wider tire is overinflated, or the narrower tire is underinflated!

Right now, I switched to my 38's, and I'm dog slow. I went to them for (a) training and (b) mud flotation. Either I make it home, or I'm walking.