First disclaimer, I'm not doing helmets or selling helmets for anybody. I just have that problem of curiosity and because I still position a lot of racers I needed to know some facts. I went to the A&M tunnel on August 1st, got a volunteer to test some things and here are the results. Note**** helmets test a little different on different riders because of back shapes and pelvis rotation. These results are for this rider but I think they generally would have the same results.
The bike was a New Look TT frame, FSA aerobars, 50mm Blackwell wheels front and rear. Wheels were spinning, rider was 6'2" - 170 lbs, multi-time Ironman racer, Mark Miller, owns a bike shop in lafayette, La. He supplied most of the helmets, Mark has been to the tunnel with me many times and knows how to sit accurately and repeatable.
First run for base line in his current race position with an untapped Giro Atmos helmet, rear water bottle cages.
Yaw 0 2.5 5 10 15 20
untaped Atmos @ race angle 7.64 7.75 7.41 7.47 7.56 8.33
taped vents Atmos @ same race angle 7.47 7.12 7.31 7.10 7.73 8.16
L. Gar. rocket, tail up 6.97 7.24 7.21 7.26 7.00 7.16
L. Gar. Rocket tail dn 7.24 6.95 7.03 7.03 7.28 7.73
Bell/ Walmart Impulse, taped 7.27 7.63 7.36 7.27 7.38 7.98
Rudy Syton w/flaps 7.31 7.50 7.29 7.07 7.31 7.74
Rudy Syton No flaps 7.24 7.34 7.33 7.18 7.28 7.81
For me, same setup as test #2 - taped vents, Atmos - Landis High hands replicated pretty close: 7.89 7.73 7.62 7.53 7.58 7.97
I'll stick with lower hands for a little longer.
Andrew Coggan can figure the speed/time for you for fun.
New Blog - http://www.johncobbresearch.com