Aerometers and Marginal Gains

If real time CdA is difficult to measure because the test is dominated by other factors (low signal to noise ratio), doesn’t it mean that CdA-related gains are even more marginal than other marginal gains?

Hey

First of all, thank you so much for the podcast. Every time, I learn more and more about all the small details, which compined can make such a difference. And, with all my new gained knowledge, I’m not only helping myself, but also my 62year old dad, who despite his competitive nature, just doesn’t get why tires and chains are so important. But, he is getting there, and he is feeling the difference.

My questions is regarding the effectiveness of well placed tape, with the purpose of smoothing out surfaces, covering gaps, and the like.

My main focus is long distance triathlon, so I am looking for all the small savings I can get. Right now, I ride af Felt IA Disc, which for example, has a gap between the front brakecable-cover and the fork. This gap, creates a little crevasse, which I have now covered with som electrical tape. My guess being that air would otherwise get caught in the crevasse, and the result being turbulence and drag.

I have also taped over the stembolt-holes, again, to avoid having four small holes pointed into the wind.
I’ve identified several more places, where well placed tape could help smooth things out.

So the question is, is this worth doing or am I just wasting my time? And are there more to consider, for example, to shape the tape more pointy, instead of just covering a gap? Maybe using something like Tesa 4613 tape, since the slight ribbled surface could work like the dimbles on a golf ball?

Again, thank you so much, and have a great day!

Nick

Georg: We’ve measured increases in rolling resistance with decreasing ambient temperature in field tests. I think Tom Anhalt estimates that Crr changes a bit more than 1% with each deg. C.

Nice podcast as always. Regarding the topic of the temperature depency of the rolling resistance: on the one hand, as mentioned, the pressure can vary but on the other hand the loss factor of polymers can also depend on temperature. I don’t know if the changes are relevant or not but a second argument that the rolling resistance could be temperature dependent.

Very nice, good questions from Hottie, good responses from Michael.

The promise of the new generation of aero sensors is that they would make drag testing easy. I’m not sure that’s achievable with the current devices: I think they can widen the range of conditions under which one can test, which makes finding an appropriate test venue easier, but they’re not a substitute for good protocols and careful execution. They let you test more frequently, but not necessarily more accurately or precisely. When I teach I often emphasize fundamentals so sometimes I think it can be good to do a few “plain” VE tests on laps to get to understand problems, limitations, techniques, and protocols. As Michael noted, slope and elevation measurements are critical, and laps of the same course mostly side-step that issue.