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http://www.nyvelocity.com/content.php?id=1281

I enjoyed poking around the nycvelo site with your articles/tests on helmets and covers. I'm wondering why you didn't just get a buddy to come over to be the "helmet holder"?

So what is the actual sensor that is used for wind tunnel tests to measure drag?

I'm guessing they use some kind of a strain gauge under the bike holder? I can't use a helmet holder on this rig. Maybe next time?

I'm guessing they use some kind of a strain gauge under the bike holder?


Weren't they measuring the amount of drag from Armstrong's number placement by using a little stick with a streamer on it? If the stick isn't connected to Armstrong (there was a 2nd dude in there holding it), then wouldn't the only way to measure that be on the "exit" end of the wind tunnel? Not on the same "system" as the bike/Armstrong?

lol. Please excuse the chitty explanation... I'm no wind tunnel/physics expert.

At the risk of hijacking the thread, I've always wondered how they determine the overall drag coefficent for a riders position. You'd need to have measurement methods everywhere. I'm a Mechanical Engineer but have never done aerodynamic "stuff".

At the risk of hijacking the thread, I've always wondered how they determine the overall drag coefficent for a riders position. You'd need to have measurement methods everywhere.
F_d = 1/2 rho Cd A V^2. Measure F_d, A, and V and you can calculate C_d for know air density, rho.

Weren't they measuring the amount of drag from Armstrong's number placement by using a little stick with a streamer on it? If the stick isn't connected to Armstrong (there was a 2nd dude in there holding it), then wouldn't the only way to measure that be on the "exit" end of the wind tunnel? Not on the same "system" as the bike/Armstrong?

lol. Please excuse the chitty explanation... I'm no wind tunnel/physics expert.

they were not measuring the amount of drag when they were doin that..He was looking for a position that had "dead air" to place the number/radio receiver so him being in the tunnel didn't matter at that point.

I'd be interested to see how shoes with buckles instead of three simple straps would fare against their simpler counterparts, both with and without shoe covers.