by NovemberDave on Wed Aug 07, 2013 12:05 pm
SSpring -
I don't know if you're aware of it but we tested our Rail wheels versus a 404 in the A2 wind tunnel. The Rail was slightly faster than a 404 at low wing angles, and slightly slower at wider wind angles. If you average the difference across all angles from 0 to 20 degrees, the 404 is very slightly faster. We're fine with that as the 404 is over 10% deeper and aerodynamics are just part of the whole package. For example, in addition to a wider internal width, we have more spokes. In fact our wind tunnel wheel had 24 spokes, which is an aerodynamic detriment to the 20 holes our front wheels are built with. Enough to erase the very small gap to a 404? We'll find out on our next round of tests.
In any case, for your hierarchy to hold up, the Light Bicycle 45 would have to be demonstrably faster than a 303. The difference between a 303 and a 404 are well documented. Since, unlike most other tests, we actually tested against a relevant benchmark wheel instead of the slowest wheel we could possibly find, we have the benefit of knowing that the difference between a Rail and a 404 is much less than the difference between a 303 and a 404. Is it really plausible that the rim you think is fastest actually improves so much upon the rim it copies?
Subjectively, as the Rail's designer, the Rail looks absolutely nothing like a hybrid-toroidal shape. It's far from conclusive that Zipp's shapes are superior. Bontrager shapes are very good, test very well (their test protocol provides better comparisons than what any other major brand has done), and differ from Zipp's in similar ways as ours does.
You have obviously spent some time reading about rim design which is commendable, but there is much more than what you've posted. One of the most important lessons in rim designs and aerodynamics in general is that what very highly trained people think 'ought' to work often doesn't. This is why guesses and opinions about what is faster than something else don't work. Until you test, you don't know. It's that simple.
Dave