Time to replace my race tires for 2017. Last year I settled on a 23mm GP4KsII in the back (Super 9) and a 22mm Attack up front (808 NSW). I realize these both run 1-2mm wider than spec in the real world. I’m considering whether the 23mm GP TT would be an improvement up front. Data from Tom A’s blog for the 22mm Attack on a Flo 9 suggests it’s a very good choice considering both crr and aerodynamics. Unfortunately they didn’t test the GP TT, so my question comes down to reasoning out whether the better crr of the GP TT trumps the better aero performance of the Attack as a front tire on an 808 NSW…for a ~152lbs rider at 22-25mph. I’m not interested in the SS at this point
After a bit of researching the differences between the Flo 90 and my 808 NSW in looks like they both have nearly the same internal width (17mm vs 17.25mm) but the 808 NSW is 2.4mm wider in the brake track and 1.8mm wider at the widest part of the fairing. Since the internal width is the same I would assume a given tire would have the same shape on either wheel, but the extra width of the 8087 NSW would definitely have an effect on the aerodynamics of the tire/wheel system. I’m tending to thin the wider Zipp is a good thing considering that 23mm Conti tires tend to actually run 24mm+ in the real world.
If you look at some of the roller data out on the interwebs the 22mm Attack doesn’t seem to test very consistently. If I recall, TomA refers to his 22mm Attack as a “magic tire” because he had previously tested other samples at a higher crr. IMO, a 23mm GP4000 SII is a good choice for the 808 NSW. Maybe go with the TT if you’re pretty well convinced you are a low-yaw rider.
Yes - he tested three of the Attacks 2 years ago, one with 135 miles on it and a new pair. The 135 mile “magic tire” came in at .0029 and he notes it as an outlier. the two new tires averaged to .0036. He later tested one of those new tires after 118 miles of use and got .0036 again. He also tested a new one in 2014 and got .0035. So I think with the exception of the “magic tire” the Attack seems to test out very consistently.
Tom A. crr spreadsheet
bicyclerollingresistance has also tested a 22mm Attack II (2016) and it falls out near the top of their rankings - slightly better than the 25mm GP4k but not as good as the 25mm GP TT.
After a bit of researching the differences between the Flo 90 and my 808 NSW in looks like they both have nearly the same internal width (17mm vs 17.25mm) but the 808 NSW is 2.4mm wider in the brake track and 1.8mm wider at the widest part of the fairing. Since the internal width is the same I would assume a given tire would have the same shape on either wheel, but the extra width of the 8087 NSW would definitely have an effect on the aerodynamics of the tire/wheel system. I’m tending to thin the wider Zipp is a good thing considering that 23mm Conti tires tend to actually run 24mm+ in the real world.
Holy shit, I thought I used to get anal about this stuff. Kind of a relief to be on hiatus for now…
Why no interest in the SS? That’s what I ran last, although the current specs are probably different.
Holy shit, I thought I used to get anal about this stuff. Kind of a relief to be on hiatus for now…
Yup I tend to approach things analytically and logically and I know there is a lot of data out there on tire crr, aerodynamics and testing various combinations of tire/wheel. It’s challenging to sort through it all though and piece together the best decision. Plus, I’m at the point where a couple of watts could make a difference. I could just slap on a set of GP4ks and call it good but I know that isn’t the fastest option.
I seem to have a psychological hurdle to get over with the SS that I’m not ready for yet. It may be worth only marginal security but I don’t want to give up the Vectran belt for puncture protection. The 4k/Attack/TT all have it. The SS does not.
Anecdotal data point on the SS puncture reliability: I only ran them up front and used a more ‘robust’ tire in back ~ and all my flats were still in the back anyway…
I tend to approach things analytically and logically and I know there is a lot of data out there on tire crr, aerodynamics and testing various combinations of tire/wheel. It’s challenging to sort through it all though and piece together the best decision. Plus, I’m at the point where a couple of watts could make a difference. I could just slap on a set of GP4ks and call it good but I know that isn’t the fastest option.