That is a very tough call on just one test with each helmet. The difference between the two runs was 0.6% and 0.23 KPH (0.14 MPH). Even though the faster run had slightly lower power, there could have been a tiny difference in the wind or a slowdown at a different spot that made a difference. I would probably do a few runs with each before I made a call.

Each test was a 30K correct?

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

I'd say good first attempt but you need more testing. Try shortening your loop and doing more A/B repeats. Above all else be safe (no harm in scrapping a run) but try to not use your brakes and be consistent about when you sit up. 1km is plenty long especially if you do 10 A/B repeats.

Yes. Same start, stop and U-turn location.

^+1

30k is a long time to keep other variables minimalized.

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My Blog - http://leegoocrap.blogspot.com

What greenpelase said.

more A/B runs and much shorter distances. That will give you a better data group to work with

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

It's great to see people doing field testing.

Firstly, if you haven't already, search for the 'Platypus' thread on here and read it.

Secondly, put the rides into Golden Cheetah Aerolab to see if you can make it agree with BBS.

Thirdly, there are plenty of variables that could affect the result: wind, traffic, braking, air density, tyre pressure, etc etc.

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Developing aero, fit and other fun stuff at Red is Faster

Thanks. I tried testing a week before but it was much more windy and I didn't have a long section. That test had the "B" 1 second faster on 6 miles of testing. I figured there was no way that was conclusive.
I agree that maybe a few more test would help.
and from all the info I have gathered from here. "A" should be faster than "B" most of the time. Maybe I am that person that "B" is a faster helmet.

Thanks! I had not seen that thread. Surprising with how much I am on here. I think I now have my answer.

For what it's worth, you should never go into a test with a preconceived notion of what's faster/slower. You'd be surprised how that can alter things like holding position, discipline to coast in the same area, and attention to detail (this is a biggie!) like being sure your straps are snug and nothing is flapping about. I caught myself doing that last year while testing a Bontrager Ballista. Subconsciously I'd told myself "no way this is as fast as XYZ" and I didn't really adjust the straps properly. I realized that at the end of the session so I adjusted the straps, came back the next day, tested again, and the delta between the Ballista and my Advantage 2 had dropped by half! It was still large and still slower but it just reinforces that details matter!

Triathlon's fifth discipline (equipment optimization) is all about attention to detail. Every now and again you score a big gain but, most of the time, it's all about cumulative marginal gains. Approach field testing as a true scientist with no "hope" for a particular outcome. Do shorter loops and more A/B/A/B/etc and don't even look at the data until you get home. As another poster mentioned, using Aerolab inside of Golden Cheetah with the "Chung VE" method can get you really solid data.

I'm just adding to the chorus here, but I'd say that the only thing you learned is you went faster in one than the other. Even though there was "light" wind, even a little bit can make a huge difference. We have a TT course that runs along a river here. One side if pretty sheltered by a mountain side, the other is the river, which is open. The wind even when light makes a huge difference. When I've done VE testing, my results are very close to what I get in the wind tunnel and trackaero testing. If I plug the numbers I get in on this course they are much much lower. Some of this could be due to Crr, but the roads aren't great. My guess is that this course is fast simply because of the way the wind swirls on that course.

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Heath Dotson
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