How hard was the wind blowing?

[salsabike]

Okay, here it is as Chris explained it to me. Fluid drag force (air is a fluid—it takes the shape of its container) is proportional to velocity squared. Factors include the density of the fluid (so air is not as dense as water, for example); the drag coefficient of the object (bike, your clothing, etc.), the projected area in direction of motion (that’s why you get aero, to decrease your area), and velocity.

The drag force increases as the square of the wind velocity relative to the bike. Downwind, you subtract your speed from the wind speed. Upwind, you add your speed to the wind speed. So, for example, you have a 15 mph wind and your bike is going 10 mph. Downwind, the push you get is proportional to (15-10) squared = 25. Upwind, the resistance is proportional to (15+10) squared = 625. Fun, eh? Thanks to my cool engineer spouse for the explanation.

[marni]

that is the most lucid and useable explanation I have heard. Thank you to your and your husband.

[Melalvai]

The drag force increases as the square of the wind velocity relative to the bike. Downwind, you subtract your speed from the wind speed. Upwind, you add your speed to the wind speed. So, for example, you have a 15 mph wind and your bike is going 10 mph. Downwind, the push you get is proportional to (15-10) squared = 25. Upwind, the resistance is proportional to (15+10) squared = 625.

That is so cool to have an actual science type explanation and a formula of what I have known for a long time. Thank you.

I have more than once gotten myself in trouble because I was going into a wind and working harder than I realized.

[salsabike]

I know! It's oddly gratifying to grasp the magnitude of all that work we're doing when we plow into a stiff headwind.

[marni]

today was a warm 80 degrees and windy two shots of pickle juice ride. I was averaging 14 mph and the wind was 20 mph which means that the proportional resistance force was 1600. I did 50 miles mostly with headwinds today and 45 miles yesterday. No wonder my legs my legs are really tired .