roady wrote:
aravilare wrote:
roady wrote:
Nick B wrote:
Not that close. People spend thousands of dollars to get less performance than the difference between tires.
Tires represent the best watt/$. Buy the fastest rubber.
They're pretty close...
I agree, buy the fastest rubber. I don't think "what's fastest" is an easy question to answer. Depends on the wind, how fast you're going, depends on whether or not the Crr of your particular tires match up with the ones Tom tested, depends on the accuracy of Specialized' wind tunnel claims for its cotton tire--and the wheel on which it was tested. A lot of "it depends".
The Attack/Force combo, the Specialized tires, the new Zipp tires and the 4000S are all good choices. I think "what's absolutely the best" is a bit tougher riddle to solve than you suggest.
Given the recent evidence that actual yaws experienced are significantly lower than previously quoted, the GP4000S advantages are mostly negated. Sure, there's variance but that's not to say there's not a fairly clear choice. It's like ignoring a correlation (TRIMP vs. load) because it has a confidence interval.
No, it's actually not like that at all. But if you want to believe that, it's cool. You're making a lot of assumptions in reaching the conclusions you're reaching-all of which I addressed above. For instance, it's surprised the bandwagon has devolved to "this tire is fastest" when the Zipp tire and the Conti Force roll just as fast--and neither of those has a glued-on tread (which generally is less aerodynamic). There's zero evidence that this tire is faster than either of those 2 tires? Again, not saying it's a bad tire, by any means--I imagine it's a really good choice. I also think there are a lot of "what if's" that are being completely ignored, and that there are other choices that are likely as good, and possibly better.
One thing I'd suggest is for folks to test the Crr of some tires themselves, multiple lines of inquiry and all that--vs. reaching such definitive conclusions.
The Continental Force from Tom's data is used and is also marginally slower than the Turbo Cotton (if you look 50kph column, you can spot the 1 watt difference). The SS is well-worn. The only Zipp tire with lower Crr is a tubular and 27c.
Regarding the aero question, I suggest you actually read up on real world yaw exposure (e.g.,
http://static1.squarespace.com/...ngle+White+Paper.pdf) and notice that high yaw (where previous data on tires shows real divergence) are very rare. At low yaws, even this "generally is less aerodynamic" assumptions is largely mitigated.
Sure, you could get a tire with worse Crr than Tom tested, but then you are certainly just arguing confidence intervals, just as asking people to run more tests on their own is.
