Some of the trackies know have talked about certain indoor velodromes as being significantly faster as a result of how these venues are climate controlled: temperature, pressure, and humidity.

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rho goes down with temperature and your aerodynamic drag is directly proportional to rho. As an example, at 50F, an online rho calculator gives 1.25 kg/m^3 vs. at 80F 1.18 kg/m^3. So call that roughly 6% less drag, which is significant!

play around with this a little:

http://bikecalculator.com/veloUS.html

I imagine you would want to have the building slightly depressurized, humidity very low, temperature a little higher. It can be done very cost effectively with heat recover equipment (ie... a really big dehumidifier). With low humidity, athletes will still stay cool.

I'll mentally remind myself in my next hot race that it's OK because the drag is low, the drag is lower.

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Play around on a free account at bestbikesplit.com and you can change temps to see different courses

Significant depressurization isn't feasible because buildings are not capable of withstanding it. Also, humid air is less dense.

Another factor with temperature is that tires have lower Crr.

Yes, this is often why races like Tahoe and Boulder had great bike splits even at altitude. You give up some watts, but you typically got back a great deal of that speed through warm air and altitude making air less dense.

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In order of importance.... low pressure, high temperature, & high humidity = fast air

So the quick answer is "Yes it does"

What about power loss from 50 to 80°F?
At some point there has to be a break over point where the power available and total drag curves intersect. Whatever that temperature is, all things equal, a person cannot be faster above that temperature. It's pretty dreadfully hot in California right now and I can assure you I am not faster as a result. Quite the opposite actually, I've found I'm fastest when I can stay cool (but not fight to stay warm).

I thought I had read that running was something like 2 seconds/mile slower per degree F above something like 60. I thought it was based on varying environmental temperature, measuring core temp, and perceived effort. I thought they had used a big name in running too...

1, One tends to cool pretty effectively when moving through the air at 20+mph as long as the temperature and dew point at somewhat reasonable. Most won't loose power moving from 50*F to at least mid 70s.

2. Intensity would certainly influence one's ability to shed enough heat to be a problem. I did a training ride with a friend last night at her IM power. It was 89*F with the sun fairly low in the sky and we were quite comfortable.We'd have been broiling f we'd been hammering Olympic distance power levels on the same ride as that much heat would be too much to lose without overheating.

YMMV,

Hugh.

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Genetics load the gun, lifestyle pulls the trigger.

The power loss from high heat is going to vary a lot from one individual to another and also vary a lot depending on how heat adapted a given person is and how long an effort is being done. It is therefore going to be a lot more fuzzy than the super concrete math of how temp impacts drag. But no doubt you are right that there will be some break over point where more heat causes a net slowdown. Personally from 50F to 80F is definitely in the net win zone for me. If I had to make a guess for myself, I'd say that for an hour-ish effort 90F is pretty close to the break over point; I'd estimate my fastest 40K TT time would be at roughly 90F.

Some also have HVAC systems that accidentally create a current that circulates, and if it's in the same direction the rider go they are basically riding with a subtle tailwind.

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