# General Cycling Discussion - Wind vs. hills

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.

View Full Version : Wind vs. hills

Digital Gee
09-11-05, 05:30 PM
I had a great ride today on flatland, but with LOTS of wind, and I got to wondering -- is there some kind of conversion chart which compares wind to riding up hillls? Felt like I was going uphill a lot today, but the terrain was flat -- just lots of wind.

So can one compare one to the other?

Mirage-t
09-11-05, 06:44 PM
I'm not sure there is an actual way to calculate it because your wind drag is differenent than others and there are to many other unknown perameters. I treat head winds and long climbs the same. Just pace myself and don't burn out, I found it very easy to burn myself out on long flats with a head wind because I thought I was going to slow. Head winds can be battled though with a group willing to work together...big climbs, your on your own.

Mentor58
09-11-05, 07:08 PM
head winds are one of the reasons that I've got aero bars on my loaded touring bike. A hill you can see the top of, but that wind just seems to go on forever. It does seem like that some of the math whizzes that we have here should be able to post some sort of basic comparison. There are some sites, if memory serves me, that post the watts required to maintain various speeds, and the vast majority of that goes to defeating drag (going 10 MPH into a 20 MPH Headwind is ALMOST the same as going 30 MPH into no wind), and I seem to recall some page that had a listing of watts required to climb a hill at certain speeds and weights. I'm sure that there isn't a nice easy ratio like 10MPH wind = 5% grade, that would just make life too easy

Steve W

Eggplant Jeff
09-11-05, 07:16 PM
Your conversion will also have to take into account the fact that hills have to be on your side 50% of the time (assuming the starting and ending points of your trip are the same), whereas the wind conveniently shifts so it can be in your face 90% or more of the time.

jur
09-11-05, 08:31 PM
I asked this sort of question a while back in the road bike forum, it yielded about 5 pages, most from posters who completely misunderstood the question. Other than the subjective opinion that they feel different, there is no fundamental difference. Yes, you get a bit of an angle to the bike on a climb so your posture may be slightly different. Personally I'd rather climb a hill than ride into the wind.

TheRCF
09-11-05, 08:43 PM
I also feel like fighting the wind is like riding uphill, though the angle difference on a hill must make some difference in how you are using those muscles.

I'd like to know how wind affects you at different angles, such as if you have a 10 mph wind coming towards you from 45 degrees off to the side, how would that compare to a direct headwind. After all, on average, few headwinds would be directly against your line of travel (though it seems like they all are!).

Eatadonut
09-11-05, 08:57 PM
Wind is an invisible hill that occasionally turns sideways and drops you into traffic.

Medpilot
09-11-05, 10:53 PM
I had a great ride today on flatland, but with LOTS of wind, and I got to wondering -- is there some kind of conversion chart which compares wind to riding up hillls? Felt like I was going uphill a lot today, but the terrain was flat -- just lots of wind.

So can one compare one to the other?

"at slower speeds, each 5 mph of wind speed equals ~1% of grade i.e. a 20-mph headwind would equal a 4% hill"

http://www.cptips.com/windrde.htm

steveh2
09-12-05, 01:02 AM
Your conversion will also have to take into account the fact that hills have to be on your side 50% of the time (assuming the starting and ending points of your trip are the same), whereas the wind conveniently shifts so it can be in your face 90% or more of the time.

I don't know -- around here it feels like the hills shift the same way, so you are going uphill 90 percent of the time.

SteveRogers
09-12-05, 01:46 AM
I asked this sort of question a while back in the road bike forum, it yielded about 5 pages, most from posters who completely misunderstood the question. Other than the subjective opinion that they feel different, there is no fundamental difference. Yes, you get a bit of an angle to the bike on a climb so your posture may be slightly different. Personally I'd rather climb a hill than ride into the wind.

Though wind in your face does have a nice cooling effect on a hot day....much better than a hill in your face! :D

cyclezealot
09-12-05, 01:50 AM
This exact point has occured to me every time I have to pedal dowhill to maintain a decent speed.
One incident I reacall that was sorta freightning..Taking off on a downhill, had to pedal to go downhill..Winds were gusting from all directions..Taking off downhill accelerating was such a problem..Felt sidewinds was going to knock me over.

skookum
09-12-05, 09:01 AM
There is actually an online calculator (http://www.kreuzotter.de/english/espeed.htm) where you can figure out your speed for a given power output. Some of the variables are wind speed and hill angle, so you can work out what slope is equivalent to what windspeed for any given bicycle.

I don't know how realistic this is, but its fun to play with