Sorry for sounding absolute and I am always willing to accept new facts when tests or real life experience show, that things are different. We are here to discuss.Hexsense wrote: ↑Mon May 28, 2018 12:55 amWhile we still agree with information we observed from other people's tests.
Each time you state the observed speculation, you sound more and more generalized and conclusive like it become indisputable fact.
I fear that this can bring us too far from what data can provide us. And something might turn out to be not completely right. Consider using Scientist's way to talk from observation: claim and generalize a bit less.
But e.g. the crosswind stability of Reynolds teardrop shape rims (not Strike SLG!) has been seen in two Tour Mag. tests, the Triathlon Mag. test, the DT Swiss/SwissSide test and personal experience from triathletes I met on the road (and those also complained about the 454 NSW in that regard).
Yes, that was an exaggerated formulation. But people expect higher gains of their aero wheels, than they will ever be able to achieve anyway (just those few watts) and with an overlapping tire it's nearly gone. Every wind tunnel test of the manufacturers is done with the matching tires and front wheel only.Hexsense wrote: ↑Mon May 28, 2018 12:55 amBased on what we've seen so far, there are some small details i see a bit different in your post:
1.) Aero benefit of deep wheel is not completely gone. It's just reduced. Yes, based on Specialized claims: Roval CLX32 with matching tire width is more aero than Roval CLX 40 which is too narrow for modern tire. But the CLX40 is still more aero than box section rim anyway.
In direct head wind the differences are tiny, we agree on this? When you turn your wheel, the frontal area increases, so the drag should be higher, right? But the aerotests show us, that the drag is actually reduced - because the sailing effect ("lift") takes in and it is higher overall and compensates the higher frontal area. But this just doesn't work with an overlapping tire. The turbulences will eat up most of the benefit.
That was also an exaggerated formulation - I meant a 25mm tire on a 21C rim with 28mm outside, so a tiny overhang doesn't matter or is even better. A 28mm tire on such a rim will be worse, also in the rear. I just wanted to make clear, that the 105% rule doesn't help here.Hexsense wrote: ↑Mon May 28, 2018 12:55 am2.) Tire wider than rim in the rear wheel still have negative effect to aero (it does affect aerodynamics negativly) . It's just not nearly as bad as the front. Leading edge got shielded by seat tube, tailing edge when the tire is big and end abruptly still reduce aero-ness. With combined data from Flo and Silca's tests , we do rear wider than front because rear bear more weight and load than front wheel, bigger tire in the back should save more watts through rolling resistance than it lost by a little bit of being less aero. Hence could be faster in most conditions.
And that's why Enve has slimmer rims in the rear:
And aerotests should always be combined with rolling resistance, but what kind of surface to choose? One should take smooth and rough tarmac and check with different tire sizes, that would be a very complex test.
Here the author of the Silca Blog is looking back on the data they measured more than a decade ago: https://forum.slowtwitch.com/forum/?pos ... 3#p6350253
And have a look, what he is riding.
But this is really not a topic to get upset about - rather why our countries spent a multiple budget on defence than on infrastructure and roads seem to get worse everywhere. We are here in an international forum and I don't think we want to kill each other causeless... Peace!
