Originally Posted by
Kotts
In addition, a headwind hurts your road speed more than an equivalent tailwind helps it.
This is not correct. Play with an online calculator, or do the math yourself.
(At least as far as _wind_ is concerned. Eventually, as speeds increase due to a strong tailwind, rolling and bearing resistances become much more important.)
Originally Posted by
Kotts
The power required to overcome aerodynamic drag increases with the square of the speed increase. So, given the same power output, even though your "airspeed" decreases with the tailwind just as much as your "airspeed" increases with the headwind, your road speed is decreased more by the headwind than it is improved by the tailwind.
Cubed of the speed increase. Actually, square of the relative (to the wind) speed increase times speed increase. Regardless, what it means is that _at the same power_ the relative decrease in wind with a tail wind helps you more than the head wind hurts you. You have to look at the inverse relationship to what you suggested.
Originally Posted by umd
Just because it is not "intuitive" to you does not mean it is not blindingly obvious to others...
Originally Posted by Kotts View Post
"In addition, a headwind hurts your road speed more than an equivalent tailwind helps it."
Yes, I didn't want to muddy the waters with that more complex discussion. But I did cover it in my next post:
Originally Posted by umd View Post
"That's not taking into account that a 10mph wind doesn't affect each direction equally either..."
This is ironic.
Originally Posted by mxl
Then in the real world, the second part of the problem is that for every wind angle other than 0 and 180, the fact that cross winds present themselves as more of a headwind when the force vectors are taken into consdieration. That's the point of the HED tool.
This is not necessarily bad. A side wind _might_ actually increase your speed. (Theoretically, as in the whole "negative drag" can o' worms, though the numbers linked to earlier from Sheldon Brown show that sidewinds are worse than the equivalent headwind component. Though this set of data does not account for any streamlining or dimpled wheels, to my knowledge.)