"Tailwinds don't help Everesting cyclists."

[Tenkaykev]

An interesting article in Ars Technica today looking at the effects ( or lack of ) tailwinds.

https://arstechnica.com/science/2024/09/tailwinds-dont-help-everesting-cyclists/

 

[Ming the Merciless]

Conversely if one has a tailwind when going downhill does it help?

 

[ebikeerwidnes]

Conversely if one has a tailwind when going downhill does it help?

I'm sure Chris Boardman could give us a 1 hours talk on the exact benefits and how to optimise them

but in my case I doubt that I would even know there was a tailwind - I only ever notice headwinds (and up the ebike assist levels!!!)

 

[Drago]

My response is something rollocks.

The aerodynamics are well understood, and the faster one goes the more resistance increases as a square of speed.

A tailwind might not help as a push or any kind of sail effect, but where it does score is reducing the velocity of the air relative to the rider, and thus the resistance.

The resulting advantage may be slight, nay, even immeasurable, but well established physics tells us it is there regardless of the nature of the gradient.

 

[lazybloke]

The article is worthless if it didn't consider these:

 

[presta]

I think people on here are getting the wrong end of the stick, they aren't saying there's no benefit from a tail wind, they're saying that if you cycle a round trip the tail wind that helps you one way has less effect than the head wind that hinders you on the way back. Unless you're doing a one way trip the overall effect of a wind is always negative.

 

[Dogtrousers]

I think people on here are getting the wrong end of the stick, they aren't saying there's no benefit from a tail wind, they're saying that if you cycle a round trip the tail wind that helps you one way has less effect than the head wind that hinders you on the way back. Unless you're doing a one way trip the overall effect of a wind is always negative.

And by definition you will be cycling a round trip (multiple round trips in practice) if you are Everesting.

(Unless you happen to have a particularly large hill to climb like ... er ... Mount Everest)

 

[Beebo]

And by definition you will be cycling a round trip (multiple round trips in practice) if you are Everesting.

(Unless you happen to have a particularly large hill to climb like ... er ... Mount Everest)

But surely it’s better to go downhill into a head wind rather than uphill?

 

[Alex321]

But surely it’s better to go downhill into a head wind rather than uphill?

Depends on how steep and twisty the hill is. If you would need to brake for corners, the the headwind probably has little effetc. But if you could freewheel all the way down and hardly touch the brakes, then it will have more slowing effect, as you willl be going faster, so bgenerating more resistance.

 

[figbat]

But surely it’s better to go downhill into a head wind rather than uphill?

I would say the opposite is true. Aerodynamic drag increases with the square of speed, so a tail wind on the descent will reduce drag by more than it is increased for the headwind-assisted climb.

 

[Jameshow]

All I know is that a headwind across the fens is like nothing else!!

 

[Ming the Merciless]

Unless you happen to have a particularly large hill to climb like ... er ... Mount Everest

Which would involve less climbing as base camp is 5,200m. But it makes up for it with technical difficulty and sneakily reducing the amount of oxygen you can get in your lungs.

 

[figbat]

Which would involve less climbing as base camp is 5,200m. But it makes up for it with technical difficulty and sneakily reducing the amount of oxygen you can get in your lungs.

But working in your favour is the reduced atmospheric pressure generating less aerodynamic drag. Swings and roundabouts really!

 

[Ming the Merciless]

But working in your favour is the reduced atmospheric pressure generating less aerodynamic drag. Swings and roundabouts really!

The jet stream does however sometimes touch Everest and you might find the headwind somewhat more fierce.

Or crevasses and seracs

 

[roubaixtuesday]

I think people on here are getting the wrong end of the stick, they aren't saying there's no benefit from a tail wind, they're saying that if you cycle a round trip the tail wind that helps you one way has less effect than the head wind that hinders you on the way back. Unless you're doing a one way trip the overall effect of a wind is always negative.

That's what the suggestion is challenging, and I think they're right.

Because
1) drag goes as the square of the apparent wind* then
2) total energy expended = distance * drag integrated over the ride
3) A tailwind on a descent will reduce that total energy because the effect is the square of the apparent windspeed.

However, as others have noted, this assumes you don't brake during the descent. It also assumes that the wind is exactly in line with the course, and the course is exactly straight. In the real world, neither will be true, and sidewinds will net increase that drag (again, because of the square effect of drag).

*apparent wind means the wind you experience ie a tailwind of your exact speed = zero apparent wind