Are you better off (faster) sitting up with a strong tailwind?
No.
Definitely in my opinion. I did a race that had multiple loops on a straight out and back course. We had a 20mph tail wind going northbound and obviously 20mph headwind going southbound. I was sitting straight up passing guys that were powering in aero with the wind at our backs. I was doing over 30mph at a moderate effort sitting straight up.
No.
You are almost always travelling faster than the tailwind (or should be), so net net you are still experiencing a headwind. With a strong tailwind people may sit up a bit more since the tradeoff between a more aero vs. a more powerful position is slightly different. In practice this is hard to accomplish with aerobars, so it’s generally best to stay in them. It’s mega-windy in Kona, but you don’t see pics of pros sitting up to “milk” the tailwind.
Actually if I am going uphill at 20 kph or less and the tailwind is 20 kph or more (you have to guess, but can usually tell), I will take the opportunity to sit up and/or go out of the saddle.
Definitely in my opinion. I did a race that had multiple loops on a straight out and back course. We had a 20mph tail wind going northbound and obviously 20mph headwind going southbound. I was sitting straight up passing guys that were powering in aero with the wind at our backs. I was doing over 30mph at a moderate effort sitting straight up.
(assuming relatively flat terrain below)
You’d have been going 35mph at a moderate effort had you not been sitting up. With a 20mph tail wind and going 30mph, you have an effective headwind of 10mph. How would being less aero into a headwind enable you to go faster than someone more aero? The only circumstances in which it would benefit you to sit up would be those in which you aren’t safe to be on a bike in the first place (think “hurricane”).
Let’s think a bit here before answering.
Are you better off (faster) sitting up with a strong tailwind?
Your “net wind speed” is simply calculated by adding or subtracting the wind speed from your speed. A 15 mph tail wind, when riding at 20mph creates a net headwind of 5 mph.
And, one important thing to remember is that wind resistance increases exponentially.
The is almost no resistance with a 5 mph net headwind. While the difference between 25 mph and 30 mph is huge.
If the tail wind is greater than your speed, you should see a benefit.
With a tail wind equal to your speed (in theory) there should be no cost to sitting up. Even with a tail wind 5 mph less than you speed, there is very little cost to sitting up. And, if you can achieve more power with no additional effort by sitting up then it’s certainly a win even with a small net head wind. There may also be a win simply by taking a break from the aeroposition, and being able to power harder when you get back into it.
But in the other direction, things get real ugly real quick. Even a 5mph head wind can change your net wind speed from 22 to 27mph which is a HUGE difference. So staying as aero as possible is critical.
2 cents. I think I’m remembering the physics of this correctly.
There is wind, and apparent wind http://en.wikipedia.org/wiki/Apparent_wind Its the apparent wind that you need to be focusing on, whether it is speed or angle.
It will be a pretty rare tail wind that would result in you not still having an “apparent” headwind and thus some benefit gained from staying aero. The slow speed climbing scenario is one exception although you’d probably be sitting up anyway.
But heck with the science, I always sit up in a tail wind since I like the sensation of going fast without trying hard, even if I could go faster if I rode normally.
I understand the physics behind it, but the reality that day was, I tried riding aero and tried riding sitting up. I was able to maintain the same speed as I was going aero while sitting up with less effort.
To me, then, that means the benefits of being in a more powerful position outweighed the drag of sitting in the lessened apparent headwind.
Wind drag increases with the square of the velocity - Force = 1/2 air density * velocity (speed) squared * drag coefficient * frontal area. Since all of those things are the same during a race (for a given position) we’ll simplify that into a big coefficient, Cbig. So you get Force = Cbig*v^2
Do the calculation, as an earlier poster said, for the difference between 25-30 mph and you’ll find that all other things being equal 25-30 mph is a net increase from 625Cbig to 900Cbig, or 275 times CBig. From 5 to 10 mph wing speed you get 25Cbig to 100Cbig, or 75 times Cbig.
You’re going to increase Cbig by the same amount by getting out of aero - but obviously 625 times that change (at 25mph) is going to be a LOT more detrimental than 25 times that change at 5mph.
If you’ve been riding around Denver lately, by all means, sit up.
70 mph winds are nearly enough to keep you spun out on flat road. When you turn around for home though, FTP+ riding is only worth a few MPH even in full tuck. It sucks! Riding into a wind like that is like having your brains sandblasted out via your helmet vents.
If you’ve been riding around Denver lately, by all means, sit up.
70 mph winds are nearly enough to keep you spun out on flat road. When you turn around for home though, FTP+ riding is only worth a few MPH even in full tuck. It sucks! Riding into a wind like that is like having your brains sandblasted out via your helmet vents.
Haha. No Sh*t. One of the few moments when you have to keep pedaling on descents in to the wind otherwise have your forward progress stop. At least today winds are back to a much more tolerable 15-20 with gusts up to 30.