I did a coast down a hill of about 0.96 miles. I had the finish marked with a line on the road, and two lines at the start - the first was where my front tire was when I took my one and only pedal stroke of the entire test - with the right pedal in the 3 o'clock position I stood on it with my body weight to get rolling. I clipped my right foot in and got in aero position. Slowly I rolled to the second line, about 25 yards away, where I started my clock. Then when I got to my finish line, I hit lap.
I tried to maintain my true Ironman position the whole time instead of my best possible position that I will try to use when I'm confident I won't run into anything - so looking forward enough to see the road but with that stretched feeling in my neck of trying to keep my head out of the wind as much as possible. First test was with the aerohead and I alternated each test, for 4 tests total, 2 with each helmet.
Run 1: Aerohead, 104.60 seconds
Run 2: Seletor, 101.55 seconds
Run 3: Aerohead, 102.17 seconds
Run 4: Selector, 102.63 seconds
Aerohead Average: 103.39
Selector Average: 102.09
Difference, 1.3 seconds, advantage Selector.
Paired, single-tailed T-Test result: 0.29
she got me going for the brake at the end of the test
I feel like over such a short test, a 1.3 second difference is a big deal, IF it is real. There was not much wind. Differing initial velocities could have a big effect on the results, even though I tried hard to control it. On the second aerohead test, a "right power meter missing" warning came up and I felt I had to clear it because I was not sure my lap button would work if I did not. I did that from the aero position and the head unit is right between my hands, so I did not really have to move much. On the second selector test, I mimicked the same motion at the same spot in the course to try to keep things consistent....
For so few datapoints, the results of the t-test do not seem awful, but certainly not something one could go publish a paper off of.
So... Did I learn anything?