Somewhere I think we lost sight of the original tire switch. Sure, what's been said about rotating weight, tire width, et cetera is all true, but does it matter. Let's take weight, for instance. A 700x23 Conti Gatorskin with wire bead (chosen for apples-to-apples comparison) weighs 280 grams. The same tire in 700x28 weighs 360 grams, so now that's an 160 gram bottle of wine in our backpack we're using for comparisons, right?

On the other hand, if you're using something like the 700x50 Schwalbe Marathon Supreme (as I am), you've got 645 grams per tire -- nearly an extra pound per tire -- and most of that weight is rotating about an inch farther away from the hub, further multiplying the inertial effect. Can I feel that difference? Yeah, I think so, but it's not as dramatic as you might expect. I'd say it's less than the difference I feel from having either tire underinflated by 10 percent or so. The worst part is having two and a half inch wide fenders, which really suck going into a headwind.