joshatzipp wrote:
The tires with the Best Crr, generally have no puncture belting and worse aero (thinner treads mean less shaping). while more aero tires will have slightly higher Crr, and adding puncture belting increases this further. For my math, a Tangente or GP4000 type tire is hard to beat for tri, good Crr (but not as good as tires without puncture belting), great aero (withouth sacrificing major Crr for better aero), and good handling/road feel. As with anything, there are options that may be better in one aspect or another, but making a good decision is about understanding the relative risks and benefits of the total package.That said, and I'm pretty sure Kraig's data/math supports this, my own math tells me that low Crr makes up for a LOT of "aero sins"...especially if one uses a true "on road" Crr (which takes into account Crr being higher due to surface roughness and the additional hysteretic losses) instead of smooth roller Crr values.
This was seen in the Trek Aerowing data that Damon Rinard originally produced. Despite it's aerodynamics being described as "a mess", the VF Record with it's low Crr still outperformed the narrower and better shaped AeroWing TT 19C up to an apparent wind speed of 20 mph (averaged over all yaw angles - and on an Aelus 50 IIRC).
It's pretty easy to see on that chart above that the GP4000S has the best aerodynamics of the bunch (the curve is the "flattest"), but due to it's worse Crr, it doesn't beat out the aerodynamically challenged VF Record until one reaches apparent wind speeds > 25 mph.
That's what I mean about a low Crr making up for a LOT of "aero sins" ;-)
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