On a cirlcular loop does it even matter. For instance i have a 7 mile park loop that i ride on alot. A few weeks ago i did a tt there. I used a disc and a decent aero position. The wind was calm and I did preety much a constant speed the whole loop. Today I was out there without the disc and a more aggressive position and went 20 seconds slower. There was much more wind today. The loop is not a good cicle though. It has a 3 mile side and a 4 mile side. the 3 mile side today went into a headwind th whole way. The backside zig zags so you have a bad crosswind then kind of turn into a tailwidn but only for a short time then back into the cross.
My question is this assuming the course is a perfect circle would you have the same time if there was no wind vs say 20 mph wind? You would have it against you half but with you half. What about on a course like mine?
Reason: Given the wind slows you down, you end up spending more time going into the wind than you do with the wind at your back. Given that, your average speed will be lower than in calm conditions.
It’s the same as going up a hill. You never make up the time lost climbing, going down the backside, because you end spending so much more time climbing than descending.
No, it’s not the same: you will always be slower on a windy day in a circular course. The technical reason for this is because frictional forces (like wind, rolling resistance from tyres) are non-conservative. (Or, in other words, because entropy always increases.)
what about an out and back course? It would seem to me that frictional forces fromt eh tires would be constant no matter what the wind was(assuming the wind is purly horizontal). if you look at a free body diagram of it assuming a constant wind speed and equal distance with a head and tail wind you would get the same frictional forces from the tires. The only difference is half of the distance you would have a negitive force acting horizontally on the rider and the the other half a positive force.
The only way I could see it would be if the positive force doesnt help as much as the negitive hurts you.
And for the hill analogy it is not the smae since you dont pedal down witht he same intensity as you go up.
You COULD pedal down with the same intensity if you wanted to and you’d still wouldn’t be as fast as on a flat course on average. Very easy to do with a power meter on a hill that isn’t silly steep.
Okay, lets do the math. Circle or out and back doesn’t really make any difference, we’ll just focus on the parts that are into the wind and with the wind to illustrate the point.
First a 20 miler on a flat no wind course. Avg. 20mph - time 60 minutes.
Now out and back.
10 miles out into the wind. Avg. speed 18 mph.
10 miles back with the wind. Avg. speed 22 mph.
Time out = 33.3 minutes
Time back = 27.3 minutes
Total = 60.6 minutes, so in this scenario you’d be 36 seconds slower with wind than without. The stronger the wind the more you lose.
Again the issue becomes the difference in time spent going with the wind versus going against. The more time spent going slower into the wind makes it impossible to AVERAGE the same speed as just riding in a dead calm at a steady speed.
One way to minimize the effect would be to work harder going into the wind and then back off coming back to make the times more equal and minimize time spent going into the wind. Again a hill presents exactly the same issue and as you mentioned we tend to work harder going up than down which does help somewhat to minimize the difference versus a flat course. Of course there is a point of diminishing returns if you work too hard and blow up.
I love how people on this board can turn what I’d take to be a pretty simple matter “no, 'cause you’d be more tired” and make it all complicated, busting out words like “entropy” and the like. You guys ever hear MC Hawking’s Entropy? Pure gold.
Out and back course is the same thing: headwind inhibits you more than the tailwind helps you.
It’s difficult to make an analogy with rolling resistance since this force is always opposing motion; plus, rolling resistance is constant (independent of speed), whereas wind resistance increases as the square power of your speed.
I love how people on this board can turn what I’d take to be a pretty simple matter “no, 'cause you’d be more tired” and make it all complicated, busting out words like “entropy” and the like
Ah, the old conundrum: does knowledge of the inner workings take something away from the poetry, or does it enhance it?
