Road Racing: Interesting Fact About Drafting

['Dale]

Drafting

 

Drafting is an important technique in road racing. Exploratorium Senior Scientist Paul Doherty explained, "The bicyclist, as he moves through the air, produces a turbulent wake behind himself. It makes vortices. The vortices actually make a low pressure area behind the bicyclist and an area of wind that moves along with the bicyclist. If you're a following a bicyclist and can move into the wind behind the front bicyclist, you can gain an advantage. The low pressure moves you forward and the eddies push you forward."

 

Suprisingly drafting not only helps the bicyclist following the leader, but the lead cyclist gains an advantage as well. Paul explained, "The interesting thing is by filling in her eddy you improve the front person's performance as well. So two people who are drafting can put out less energy than two individuals (who are not drafting) would covering the same distance in the same time." While the lead cyclist gains some advantage in this situation she still needs to expend much more energy than the cyclist who is following.

 

http://images.mirror.co.uk/upl/m4/jul2009/9/6/tour-de-france-cycling-pic-getty-243133020.jpg

Edited February 24, 2011 by AirBender

['Dale]

What a stunning train in that pic from the 2010 Tour de France.

[NeverEnder]

Interesting

 

I did not know that - so hopefully there will be less bitching about wheel suckers; since they actually have a small benefit.

[LeTurbo]

If P21 is here from the Wilde, thanks for wheelsucking helping me for about 25km.

[kosmonooit]

Is that Fabulous Fabian pulling the train?

 

Interesting article. Didn't know about the energy savings to the leader. I have read that up to 75% of your energy goes against the wind resistance whilst going solo, but wind resistance is proportional to the square of the speed (thats why they had a 80 km nation speed limit back in the 70's at the height of sanctions lol)

['Dale]

If P21 is here from the Wilde, thanks for wheelsucking helping me for about 25km.

[The Guy in Pink]

More interesting stuff,

The power required to overcome wind resistance is proportional to the Cube of the windspeed.

So to double the speed requires 8 times the power.

Consider a 55kw Golf, it can almost do 160km/hr but for 320km/he you need a 450kw Ferrari.)

What that means on a bike is that to go from 40 to 44km/hr requires 33% more power

While to go from 40km/hr to 48km/hr needs 73% more power, (unless you can slip someone)

[Meezo]

I like how Exploratorium Senior Scientist Paul Doherty, refers to the leader as "SHE"....

[SL7]

Another interesting fact is that if there are 20 cyclists following the lead cyclist - he will expend the least amount of energy

[SeaBee]

You just needed to watch Daytona 500 (or any other Nascar race!) to see that in practise, the higher speed just accentuates it... Since the guy in front dows not have the drag on his rear bumper, he also goes faster.

 

Man, those guys are nuts - bump-drafting like that, two cars looking like one... Crazy speed with the new surface.

[Wil6]

Another interesting fact is that if there are 20 cyclists following the lead cyclist - he will expend the least amount of energy

 

Or did you know if there's a strong tail wind the slip works the other way around!

[RaeTrewBrowne]

Is that Fabulous Fabian pulling the train?

 

Interesting article. Didn't know about the energy savings to the leader. I have read that up to 75% of your energy goes against the wind resistance whilst going solo, but wind resistance is proportional to the square of the speed (thats why they had a 80 km nation speed limit back in the 70's at the height of sanctions lol)

 

Sparticus is the man

[Topwine]

More interesting stuff,

The power required to overcome wind resistance is proportional to the Cube of the windspeed.

So to double the speed requires 8 times the power.

Consider a 55kw Golf, it can almost do 160km/hr but for 320km/he you need a 450kw Ferrari.)

What that means on a bike is that to go from 40 to 44km/hr requires 33% more power

While to go from 40km/hr to 48km/hr needs 73% more power, (unless you can slip someone)

This is interesting. You must be talking about acceleration power though right? To keep the speed constant, the power relationship is squared to the relative windspeed not?

[lagosloonie]

power = force x velocity. The force is the drag force on the vehicle which, in the case of air, is proportional to the square of the velocity. Hence the power is proportional to the cube of vehicle velocity. The other component of force is basically rolling resistance

[TNT1]

More interesting stuff,

The power required to overcome wind resistance is proportional to the Cube of the windspeed.

So to double the speed requires 8 times the power.

Consider a 55kw Golf, it can almost do 160km/hr but for 320km/he you need a 450kw Ferrari.)

What that means on a bike is that to go from 40 to 44km/hr requires 33% more power

While to go from 40km/hr to 48km/hr needs 73% more power, (unless you can slip someone)

 

Doesn't matter, my 35Kw motard does 0-100km/h in 4 seconds with race gearing. And will also do around 160km/h, again,depending on the gearing... And it cost even less than a golf...

Edited February 25, 2011 by TNT1

[Topwine]

power = force x velocity. The force is the drag force on the vehicle which, in the case of air, is proportional to the square of the velocity. Hence the power is proportional to the cube of vehicle velocity. The other component of force is basically rolling resistance

Yes, you are of course correct, I was confusing Power vs Force.