TT Helmet Windy Hate

Ok, first, some questions from the original article answered. These are from the comments section as well as other message boards.

This is possibly the worst experiment ever, there's reasons why they use real wind tunnels.....

Wrong. The worst experiment ever would have to involve a microwave and small animals. Maybe an M80. But seriously, feel free to rip the test to shreds, just give reasons. I'm trying to learn how to do this correctly myself.

Can you do a test with the vents taped closed?

The Spiuk had 2 grams less drag with vents taped closed. (More on what that number means next week).

I showed this to my wife and explained it and she said "Huh. Why does he want to know so badly?"

Actually, I don't really want to know so badly. I'm racing with the Spiuk no matter what. What really drives me mad are overhyped products unsupported by sound research. When I do things like this I'm hoping to catch someone in the act of making something stupid. Plus, I clearly have too much time on my hands.

@##=#<1,L>@##=#You could easily test your "finished underside" hypothesis by just taping up the underside of the Rocket. That'd be a neat thing to add to the list of data. Maybe I'd end up taping up the underside of my Rocket.

There was no change in drag when the Garneau was tested alone, with and without tape (140 grams). However, when the panel was slipped under the tail, the drag went down to 122 with tape vs 129 without tape. So it seems that taping up the underside helps, but you have to keep the tail down to reap the benefits.

Uh....how do you know the fan really goes to 22mph?

I was going by the manufacturer's specs. Since then I got my iBike back (I loaned it out to a friend) and was able to measure the wind speed. The fan blows at about 27 mph at 6 inches. The helmets were about 8 feet from the fan, where the wind speed had decreased to 13-4 mph.

Referencing Eugene " measure the ambient air, windchill, etc." There is NO WIND CHILL on inanimate objects.

A probe meat thermometer (I'm such a scientist) showed no drop in temperature.

The Shootout

Now, on to the new numbers. I got my hands on a Giro, Rudy, and Uvex to add to the test. I noticed that the numbers fluctuated quite a bit from day to day, so I tried to do the test as quickly as possible while monitoring room temperature. This test took place over 2 hours on a clear day. Room temperature didn't change, and I'm hoping humidity and barometric pressure held steady as well. I tucked the helmet straps under, to eliminate another variable. The Garneau was tested with and without a visor. The Uvex was tested only with a visor – the velcro holding it on was a little loose, and I didn't want to damage a borrowed helmet. All helmets were run alone and with a simulated back. I tilted the styrofoam head up a bit so all the helmets could sit pretty flush to the back, which was held in the same position for all helmets. This raised the drag of the bare head a bit. On to the numbers.

@##=#<3,R>@##=#Helmet Alone
Bare Head....................................109
Spiuk Kronos................................109
Uvex fp2 .....................................111
Garneau Rocket............................111
Garneau Rocket w/ visor................114
Rudy Syton Open..........................129
Giro Advantage..............................132

Helmet with back
Kronos.............................................102
fp2..................................................107
Rocket.............................................109
Rocket w/ visor................................111
Syton Open.....................................123
Advantage........................................129

Once again, some disclaimers. I'm not a scientist, nor do I play one on TV. My wind source is a joke compared to a real tunnel. I don't know my margin of error. I'm picking out one or two gram differences in the helmets, using a scale that's sensitive to one gram. My simulated back may or may not interact with the helmet like a real back. So be skeptical – these results may mean something, or nothing at all.

Last week I wondered if the Spiuk had 60% of the drag of the Garneau, since it added 12g of drag vs 20. Now I know that's totally the wrong way to think about it. This week the Spiuk added 0g of drag, which would make it infinitely better than the other helmets. Of course that's ludicrous. Next week I'll have a full mathematical analysis of the numbers, but for now just consider these numbers a means of comparison.

@##=#<2,L>@##=#I've heard that the MIT tunnel says that the Garneau is slower with a visor. Interestingly, these numbers agree.

The shocker is how badly the Giro did. Given the amount of research they claim to put in, I'm almost inclined to think that this result proves my methods suck. I was surprised enough to check it against the Spiuk two more times on different days, and always got substantially more drag with the Giro.

Now, trying to understand aerodynamics intuitively is a fool's errand, so unlike last week, I'll not speculate on why the numbers are as they are. I'll just post photos and let you decide for yourselves. Check back next week for the deluxe mathlete dorkface conclusion. Now if you'll excuse me, Schmalz is going to give me a wedgie and take my lunch money.

Thanks to SBR, Anthony Accardi, Paul Goldman, and Lee3 Malone for lending their helmets.