That Wind Effect

My wife and I headed out for a relatively short ride this afternoon. The wind blew briskly from the south, between 10-15 mph. We decided to head for the Veloway, which is partially shielded from the wind by trees.

But it was shielded only some of the time. On one straightaway stretch, we rode directly into the wind. “Wow!” exclaimed my wife. “It’s like someone put the brakes on.”

It was challenging to pedal into the wind. In some spots, I coasted to let Pat catch up to me, and when I came out from behind a sheltering clump of trees, I could feel the resistance. Speed dropped immediately by couple miles an hour.

“This has gotta be good for me,” said Pat, trying to find the bright spot. “I bet I’m burning more calories fighting this wind.”

Well, as it turns out, there is a plethora of material online concerning cycling and wind. One of the cooler tools I ran into is a calculator that can tell you how much power you need to put out to maintain a constant speed if the wind and other variables change. Here’s a look:

Let’s say you want to maintain a speed of 15 mph on a flat course. That pesky wind is blowing at 15 mph also, and you weigh 200 pounds (I wish!). You need to put out 317 watts to maintain your speed, which will burn 4.5 calories per minute.

If only one of those figures changes – let’s say the wind falls to 10 mph, the change is remarkable:

Now you only need to pump out 183 watts, and burn 2.6 calories per minute.

Now these conditions are very artificial. If I added in a grade of any kind, that would have an effect, too. But I just wanted to see what the wind would do to a rider – not hills. We already know hills are tough.

Pat has trouble with hills. But even though the wind today was challenging for her, she accepted it more readily than climbing. By the way, one figure I’ve seen says each 5 mph of wind is equivalent to a 1 percent grade. So a 20 mph wind is like riding up a 4 percent hill.

“Man, I feel good!” she said when we pulled up to the house. She always feels better at the end of a ride, but today she felt like she had really had a workout. And she had.

(Calculator from Science of Cycling: Aerodynamics and Wind Resistance. www.exploratorium.edu/cycling/aerodynamics1.html

The Cycling Performance Tips site also has a nice page on “Riding Into a Headwind.”¬†http://www.cptips.com/windrde.htm)

Comments

  1. says

    Interesting tool. Personally, I prefer hills over wind. When I get to the top of a hill, at least I (a) can see what I’ve just accomplished and (b) get to ride down the other side. You can struggle against the wind for hours!

  2. Rich F says

    I have a power meter so I can get some on the bike data. Yesterday I did 4 minute intervals on a flat road that was almost parallel to the wind direction.
    Into the wind: 286 watts, 1.367 miles, 20.3 mph
    With the wind: 285 watts, 1.706 miles, 25.5 mph.
    The wind was blowing around 10 mph, not a gale by any means. But the difference in speed at the same power output is remarkable.

  3. Chris says

    These calorie numbers seem way off. My apologies, and I am no expert, but I did an off-pace ride with a friend today, (I weigh around 160) and at 16.5 miles per hour, our calories burned (according to mapmyride) were around 55 calories per mile. It is essentially a flat course. Each mile was around 3-1/2 minutes, so that was around 15 calories per minute. Of course, this doesn’t account for wind. But unless you are talking about how many ADDITIONAL calories it takes to ride into that wind, something just seems way off. Your above math suggests that riding at 15 mph in a 10 mph headwind would burn only about 10.5 calories per mile. (2.6 calories per minute, times 4 minutes per mile (15mph)) I don’t buy it.

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