Slowman wrote:
splain me this. and tell me if i've got a problem with my reasoning.
1. 25mm is testing better than 23mm in most rolling resistance tests.
2. in the limited amount of testing i've seen, isn't 28mm outrolling 25mm?
3. wider tires are also likely to be more comfortable (lower pressures).
but...
4. almost 6 in 10 are choosing 23mm or thinner.
yes, there are aerodynamics to consider as well. is this your argument? or is there something wrong with my chain of reasoning above?
I think your premises 1 and 2 might be flawed...at a given pressure, yes, but as you point out, wider tires are typically run at lower pressures. For example, from an article right here on this site:
If you look at reasonable pressures for each tire size, you'll see that there isn't much difference in the Crr...in other words, the horizontal yellow line is more reasonable than the vertical yellow line, in regards to how tires are actually run.
So, if that's the case (and there isn't really any great Crr benefits from wider tires), for a RACE bike, I'm going to be following Josh Poertner's "Rule of 105"
https://silca.cc/...ure-and-aerodynamics To me, the driving factor for choosing tire width for a given application is the tire pressure I want to run for a given course. In other words, if the course conditions require lower pressures for comfort reasons, then I'm going to choose a tire width that allows for that pressure without causing other concerns, such as bottoming rims and/or "snakebite" flats. Of course, expected speeds/wind angles also comes into that calculus. This is how I ended up selecting 42mm wide tires for BWR this year...knowing the amount of off-road conditions, I basically wanted to be able to run close to MTB pressures ;-)
That type of thinking is somewhat opposite of how most folks approach the subject (i.e. pick a tire width and then ask "what pressure should I run?"...I like to think that it's not that wider tires allow lower pressures, but lower pressures
require wider tires ;-)
Additionally, the ROT that "wider is lower Crr" is mainly only applicable across a given tire model (and at a given pressure, as pointed out above), so there's that. For example, the fastest tire (by far) on my testing chart is a 23C (Vittoria Corsa Speed)...so, I think many are aware that there ARE fast rolling narrower tires, and that could be coming into play. "Wider is faster rolling" is a generality that has some notable exceptions.
Also, as Greg K. points out above, with wider rims, 23s are the new 25s :-) You really should be asking about "mounted width".
http://bikeblather.blogspot.com/