Wind - Cross or head
#51
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This is actually pretty funny, because here in Phx... The early morning has wind out of the NE coming from the mountains. As the day warms, the air is pushed back into the mountains... so you get a headwind heading out on the Beeline highway in the early morning. If you ride out till afternoon, your return on the same rode is indeed a headwind :|
#52
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No. Not even a little bit close. It's tempting to just add the numbers together, but it's not that simple. Think about it - how much power does it take to stand still in a 25 mph wind? The answer is zero watts, not the power it takes to ride 25 mph. A wind, even a strong one, is not the same as pushing aside still air.
It doesn't take any power to stand still in a 25mph wind, but it does take FORCE, which you obtain from the ground friction, and you compensate for this force to keep from falling over by leaning into the wind.
Just like it doesn't take any power to stand on a 20% grade until you move.
I think the internet calculator you're using is just wrong.
#53
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Hold on. The first thing we learn in the first semester physics class is the concept of Frame of Reference. The bicycle can't tell the difference between moving 30mph ground speed in still air or 5mph ground speed + 25mph headwind. The drag is the same. 30mph of wind is moving over the object.
It doesn't take any power to stand still in a 25mph wind, but it does take FORCE, which you obtain from the ground friction, and you compensate for this force to keep from falling over by leaning into the wind.
Just like it doesn't take any power to stand on a 20% grade until you move.
I think the internet calculator you're using is just wrong.
It doesn't take any power to stand still in a 25mph wind, but it does take FORCE, which you obtain from the ground friction, and you compensate for this force to keep from falling over by leaning into the wind.
Just like it doesn't take any power to stand on a 20% grade until you move.
I think the internet calculator you're using is just wrong.
Why this is true, I can't tell you. I won't pretend to know much of anything about the aerodynamics or physics behind it. But my own experience and the actual data, calculators, charts, whatever I've been able to look up do suggest that the effect of wind speed on power is very different from the effect of riding through still air at the same nominal speed.
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Mondo734
Cyclocross and Gravelbiking (Recreational)
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05-11-12 09:18 AM