The wind factor

[Rob3rt]

Really informative post, a great addition to the forum!



Out of interest, how significant are the effects of this to the rider in front? If the calculations aren't too much of a chore having some figures to this would be great! (And it would also be a great excuse to take an extra long turn at back of the pack )

Thanks!

As great as the ideal conditions are, the reality is that the aero benefits of sitting right at the back of the pack (unless the "pack" are your clubmates who are purposefully holding back and not nailing it out of the bends) are all but nullified by the effort required to maintain contact coming out of bends.

 

[HovR]

As great as the ideal conditions are, the reality is that the aero benefits of sitting right at the back of the pack (unless the "pack" are your clubmates who are purposefully holding back and not nailing it out of the bends) are all but nullified by the effort required to maintain contact coming out of bends.

That was a bit tongue in cheek, "a great excuse to take an extra long turn 2 or 3 from the front" just doesn't flow quite so well.

 

[Biker Joe]

You may be right, I don't know. But in your previous post you mentioned 'yaw' in relation to aerodynamics, not cycling.

Point taken. I have now edited that statement.

 

[ufkacbln]

Yeah cheers Biker Joe, it is very flat and open around me and have noticed that winds from near 90 degrees up to straight head winds make a huge difference to my speed, so at 90 degrees you are still creating a lot of drag with your increased profile.

Mike Burrows wrote an informing article using "vectors"

Remember them from School?

In any wind that is from 90 to 180 degrees there will be an element of head wind

 

[Biker Joe]

Really informative post, a great addition to the forum!



Out of interest, how significant are the effects of this to the rider in front? If the calculations aren't too much of a chore having some figures to this would be great! (And it would also be a great excuse to take an extra long turn at back of the pack )

Thanks!

In reality the effects are not that significant. The wind directions and the riders position on the bike change constantly.The effects of draughting are much more significant to the riders behind.
And yes, the calculations are too much of a chore. I'm no good with maths.

 

[Globalti]

This is why I never hurry when there's a head wind - the effort required becomes exponential.

 

[ColinJ]

This is why I never hurry when there's a head wind - the effort required becomes exponential.

Not when Mrs Gti is driving!

I also persuade Mrs Gti to drop me somewhere upwind (usually Blackpool) or collect me downwind (Settle) in exchange for a bribe of a hot chocolate and a scone. Doing a one-way ride downwind is good for the spirit because you feel like a riding God and you can ride your nuts off knowing you don't have to return, so the ride becomes even faster and more fun.

It is quite instructive to plug some headwind numbers into this online cycling calculator. For example - if a given cyclist needs to generate 100 Watts to cycle at 15 m.p.h., then (s)he needs to generate about 230 Watts to do the same speed into a 10 m.p.h. headwind! Unfortunately, there is no provision for altering the direction of the wind.

If you look at the numbers for doing steep climbs into a headwind, you will see that they are horrendous! I once did a climb with stretches of 20-25% into a strong wind and the effort almost killed me. My heart rate went to 199 b.p.m. yet I was barely moving!

 

[Licramite]

I want to know how when I leave the house and cycle up the valley I'm cycling into a distinct headwind
when I get to the head of the valley turn around and cycle back I'm still cycling in a distinct headwind ? !.

the wind can't be blowing in both directions. - can it.

the only time I ever seam to have a tailwind is when I put the fan behind me on my turbo trainer.

I have had occasions were I have had to pedal down the hill into the wind, If I stopped pedalling , I stopped moving!.

 

[Globalti]

Yesterday I had one of my best solo rides ever; I felt like a cycling God. I suspect it was due to the fact that there was no wind at all, rather than my consumption of red wine the night before as I've speculated in the health & training forum.

 

[nickyboy]

I want to know how when I leave the house and cycle up the valley I'm cycling into a distinct headwind
when I get to the head of the valley turn around and cycle back I'm still cycling in a distinct headwind ? !.

the wind can't be blowing in both directions. - can it.

the only time I ever seam to have a tailwind is when I put the fan behind me on my turbo trainer.

I have had occasions were I have had to pedal down the hill into the wind, If I stopped pedalling , I stopped moving!.

Let's assume the wind is blowing down the valley at 15mph. If you are cycling up the valley at 10mph (sorry if that's a bit slow but I don't know you) you will experience an effective headwind of 25mph. When you turn around and cycle back down the valley you will still experience a headwind if you cycle faster than the windspeed of 15mph. If you cycle at 25mph (maybe realistic down a valley) you will experience a headwind of 10mph.
The only time in this scenario when you don't get a headwind is if you cycle down the valley slower than the windspeed of 15mph

If you talk to pros, they say they are permanently riding in a headwind as they go so fast the windspeed is always less than their cycling speed

 

[nickyboy]

Not when Mrs Gti is driving!

It is quite instructive to plug some headwind numbers into this online cycling calculator. For example - if a given cyclist needs to generate 100 Watts to cycle at 15 m.p.h., then (s)he needs to generate about 230 Watts to do the same speed into a 10 m.p.h. headwind! Unfortunately, there is no provision for altering the direction of the wind.

If you look at the numbers for doing steep climbs into a headwind, you will see that they are horrendous! I once did a climb with stretches of 20-25% into a strong wind and the effort almost killed me. My heart rate went to 199 b.p.m. yet I was barely moving!

Rode up this hill between Xmas and New Year, not a million miles from you, into probably a 35mph headwind near the top. I must have been doing all of 3mph and that was full gas !

http://goo.gl/maps/1Iw2H

 

[Pedrosanchezo]

Yesterday I had one of my best solo rides ever; I felt like a cycling God. I suspect it was due to the fact that there was no wind at all, rather than my consumption of red wine the night before as I've speculated in the health & training forum.

You know the old saying? "If you can't feel the wind then it's behind you!".

 

[Biker Joe]

Let's assume the wind is blowing down the valley at 15mph. If you are cycling up the valley at 10mph (sorry if that's a bit slow but I don't know you) you will experience an effective headwind of 25mph. When you turn around and cycle back down the valley you will still experience a headwind if you cycle faster than the windspeed of 15mph. If you cycle at 25mph (maybe realistic down a valley) you will experience a headwind of 10mph.
The only time in this scenario when you don't get a headwind is if you cycle down the valley slower than the windspeed of 15mph

If you talk to pros, they say they are permanently riding in a headwind as they go so fast the windspeed is always less than their cycling speed

Well put nickboy. Very good

 

[Licramite]

That makes sense, the valley is uphill going out , so coming back I'm going to be going faster. its a bit like the cutting edge of a saw - set at about a 20degree angle. , shot sharp hills one way , long inclines the other.

I shall stop cursing the wind and get back to cursing the hills.

 

[ColinJ]

Rode up this hill between Xmas and New Year, not a million miles from you, into probably a 35mph headwind near the top. I must have been doing all of 3mph and that was full gas !

http://goo.gl/maps/1Iw2H

Ha ha - been there, done that on the same hill! Not quite as bad as on this occasion though ...



(Watch out for the comment to the cameraman at 3:07!)