Now that I'm at the end of the video, the other interesting thing was about turbucules on wheels - so like the sawtooth shape on zipps or the waves on princeton carbonworks.

He said that they designed a wheel with turbucules in 2015 (and also tried to do it on the drs flap on the rear wing of F1 cars). They never got it to work on the cars and on the wheels he said it added about 20% in drag, but it did reduce the steering moment, so it could add stability in crosswinds, but he said they found other ways to reduce the steering moment that did not increase drag.

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

And that's the key. Here's a situation where the theoretical world of the wind tunnel doesn't translate that well to the real world. Out on the road, how often is there zero crosswind? Any crosswind is going to move the draft vacuum column, as well as dissipate it. A slight 2.5 mph crosswind component means that the draft pocket 12 meters behind a lead cyclist going 24 mph will have moved more than a meter off his/her path. As the following rider, even if you have the space to move left or right, it's usually quite difficult to find that small draft pocket 12 meters behind a lead rider, much less stay in it as the relative wind direction and velocity are constantly changing. I'm not saying that there's no real world drafting benefit to be had within the confines of the drafting rules of triathlon. What I am saying is that, on the whole, it's considerably less than this "worst case scenario" chart suggests.

Testing for this in the wind tunnel is more difficult than just turning the bikes at an angle, because you have to line up the following bike on the same wheel path as the lead bike. This requires lateral space that most wind tunnels don't have.

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"They're made of latex, not nitroglycerin"

We can detect a reduction in drag for a single rider on a 250 m velodrome as he or she goes 'round and 'round. Even a straw can stir a bath tub.

What kind of reductions do you see in a velodrome, vs just clean air?

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

It depends on the shape and size of the velodrome (that is, the volume of air that is enclosed by the building, plus the geometry of the track). That said, you can measure the "breeze" from a single rider circling the track with a hand held anemometer. The effect is even stronger in team pursuit. Velodromes are often wider on the straightaways (because that's where the spectators sit) than on the turns where the banking is steepest. The air has to speed up there, and you can measure a large differential in wind speed between the straights and turns.