Headwind to Grade Comparison?
05-29-11 | 10:00 PM
#1
Thread Starter
Senior Member
Joined: Aug 2010
Posts: 459
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From: Denver
Bikes: Secteur, Camber, Trek 930
Headwind to Grade Comparison?
Went on a ride today and the forecast said winds would be about 25 mph and that seemed about right, and it was a headwind half the ride. It felt like about a 5% grade to me. Any rule of thumb for comparing headwind mph to % grade?
At least it feels that way.
05-29-11 | 11:00 PM
#3
Senior Member
Joined: Apr 2011
Posts: 785
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From: NW Arkansas
Bikes: Too many to count
OK!,, The power to go up a grade remains fairly constant. The power to over come
wind resistance increases on the square. To go twice as fast with 10 watts of power
requires 100 watts of power.
You have ridden up a hill with a tail wind and noticed how much easier it is. The wind
is not helping you, it is just not hurting you. Turn around and go down the same hill
with the head wind and it is twice as hard to go the same speed.
We have one slight decent and the wind is always blowing up the hill. Twenty mph is
a struggle. Turn around at the bottom, shift up two gears and you can cruse up the
hill at nearly thirty mph. This is with a ten to fifteen mph wind.
The answer is to make your frontal area as small as possible.
wind resistance increases on the square. To go twice as fast with 10 watts of power
requires 100 watts of power.
You have ridden up a hill with a tail wind and noticed how much easier it is. The wind
is not helping you, it is just not hurting you. Turn around and go down the same hill
with the head wind and it is twice as hard to go the same speed.
We have one slight decent and the wind is always blowing up the hill. Twenty mph is
a struggle. Turn around at the bottom, shift up two gears and you can cruse up the
hill at nearly thirty mph. This is with a ten to fifteen mph wind.
The answer is to make your frontal area as small as possible.
