stevej wrote:
Looks like they are assuming tire pressures between a 25 mm and 28 mm tire are the same. Based on that assumption, their data is correct. But the optimum tire pressure for a 25 mm tire and 28 mm tire for the same road and wheel is going to be different. When you optimize tire pressure for the tire size, wheel width, and road condition, the rolling resistance is going to be roughly the same between the two different size tires.
Yeah, folks always seem to forget this with the big tire stuff.
It's one thing to go from old school 19mm tires up to 23's or 25's because the average amateur racer isn't some 145 pound weight pro cyclist able to run decent tire pressures for roads on skinny tires.
A 23 or 25 on a modern width rim is usually plenty. HED for their rims state pretty low needed tire pressures for those modern sizes as people forget a bigger rim bed is more volume. The same that a new tire size is a new volume.
A 23mm on a 17 or 19mm internal isn't the same volume as a 23mm on a 21mm internal. Necessitating less pressure.
28's except for folks of a weight really needing them, are largely IMO a "rail trail" gravel tire size. Not a triathlon/road racing/time trial tire. Now, Paris Roubaix, yeah.........that's a LOT rougher than your average rail trail. So seeing a pro cyclist run a 28 there makes total sense. Even then I thought 25's were more common.
Given ALL of that, I feel like just maybe they've got motivation to push that out given some other brands these days have even wider max rim width wheelsets where 25's and 28's "match up aero wise" better.