What's a tailwind?

[thnurg]

Agree with the closing the tag with the standard / but i think [ still trumps < in the context of a forum where tags are written with [] rather than <>

Ah well. You know a thread has geeked out when there's disagreement on standards.

 

[rollinstok]

Do you get troubled by the sea breeze in Morecambe? Here in Blackpool on a warm day (we do get them) a north-westerly sea breeze sets up in the afternoon, especially at high tide. So for most of the summer it doesn't matter whether the weather's calm or not, I'll always have a headwind going home.

Yes, there aren't many days here without at least a breeze, as you say when the tide is in it makes matters worse
Having cycled both Morecambe and Blackpool prom, I think Morecambe gets the worst headwinds/ best tailwinds as it lies on a more west/east axis whereas Blackpool is more north/south. I've cycled the prom in Blackpool and felt the crosswind in one direction and a cross/headwind in the other.. at least in Morecambe we get an easy ride in one direction.

 

[Leaway2]

If the component of tailwind that pushes you along is greater than your forward velocity then getting up high would work best.

So with a tailwind simply take the cosine of the angle it is to your back (where a wind coming from *directly* behind you would be at 0 degrees), multiply the cosine of that angle by the wind speed.

This gives you a value for how much a wind pushes you along (it's rare to cycle dead downwind so the cosine bit takes account of 'wasted' wind that just wants to push you sideways). If this is greater than your forward speed then sitting up and catching the wind will help.

Otherwise, being tucked down is still the best option - if I'm cycling at 20mph dead downwind and have a tailwind of 5mph, well, the air's still resisting my motion the same as it would be if I was jus cycling through still air at 15mph.

Interestingly though (extra technical bit) - the resistance the air provides varies with the square of your speed and the energy you have to provide per second is the force required multiplied by the velocity you apply it at (how fast the pedals turn). So you have to supply about 8x as much energy per second to go only twice as fast. That's a very steep increase!!

Thanks for making it sound so simple! I must remember to put my Castle book of logs in my back pocket.