# Aerodynamics & pacelines



## tom_h (May 6, 2008)

In Nascar and other car racing, it's been shown that the reduced turbulence behind the _lead_ car in a paceline, helps the _lead_ car go even faster than it could alone. The cars drafting behind the lead car save lots of energy, but as a "train" they all go faster.

is anyone aware of credible evidence, or personal experience, that this is also true in cycling? 

ie, that the cyclist doing a pull can go slightly faster than he/she could alone ?


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## Creakyknees (Sep 21, 2003)

I think there have been 2 slightly different studies on cyclists, that set out to test the numbers associated with drafting. As I recall, one of them also looked at the "2 train" effect and concluded no benefit of the NASCAR type.

Can't recall where I saw the studies, might've been here.


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## Argentius (Aug 26, 2004)

No research in front of me, but that which I have read says "no."

The speeds and size of a cyclist just doesn't "pull" enough air for this to matter.

The "train" effect in NASCAR comes from air from the lead car continuing smoothly over the tail car rather than swirling around behind it.


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## iliveonnitro (Feb 19, 2006)

Surprisingly, the answer is yes. However, it is extremely small.

The data are on my non-linux computer, so I will post the graphs later (someone may have to remind me). Actually, it's original, company-owned research, so I'm not sure I can post it. But, I will check.

If I recall correctly though, at ~25mph, you can save up to 5% under ideal conditions.


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## asgelle (Apr 21, 2003)

iliveonnitro said:


> Surprisingly, the answer is yes. However, it is extremely small.
> 
> The data are on my non-linux computer, so I will post the graphs later (someone may have to remind me). Actually, it's original, company-owned research, so I'm not sure I can post it. But, I will check.
> 
> If I recall correctly though, at ~25mph, you can save up to 5% under ideal conditions.


Obviously I can't comment on unpublished data, but the vast amount of data which has been published to date has shown no measurable effect nor has a reasonable theoretical estimate been provided to show it. Since the precision of this data is on the order of 1-2%, any data you may have seen would have to show an effect smaller than this to be credible unless they can explain why they're seeing a 2.5 fold increase in the effect compared to earlier work.


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## iliveonnitro (Feb 19, 2006)

asgelle said:


> Obviously I can't comment on unpublished data, but the vast amount of data which has been published to date has shown no measurable effect nor has a reasonable theoretical estimate been provided to show it. Since the precision of this data is on the order of 1-2%, any data you may have seen would have to show an effect smaller than this to be credible unless they can explain why they're seeing a 2.5 fold increase in the effect compared to earlier work.


You mean have an effect greater than 1-2% difference, such that it is positively outside the error? I will certainly look it over and check.

In the mean time, can I have the link/name these white papers?


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## Alex_Simmons/RST (Jan 12, 2008)

I have proposed a method by which this can be tested in an indoor velodrome, where with enough data, effects as small as 1/2% can be detected. But I've had no real burning desire to do it since I am more interested in individual power/aerodynamics.


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## spade2you (May 12, 2009)

I suppose a real way to test this is to have a power meter and take readings at the front and in the draft to see what kind of watts are required to generate the same speed under the two different conditions.


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## pretender (Sep 18, 2007)

tom_h said:


> is anyone aware of credible evidence, or personal experience, that this is also true in cycling?


Based on principle alone it has to be true, and if you measured carefully enough with a large enough sample size you could detect it, but then of what use would that be?


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## Andrea138 (Mar 10, 2008)

I actually thought of this exact thing when I was solo in a crit and lapped someone. She started to draft me- I don't know if it actually helped while she was back there, but I knew that it could be a possibility, so I told her to leave pretty quickly.


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## Creakyknees (Sep 21, 2003)

Andrea138 said:


> I actually thought of this exact thing when I was solo in a crit and lapped someone. She started to draft me- I don't know if it actually helped while she was back there, but I knew that it could be a possibility, so I told her to leave pretty quickly.



what? really?

you're allowed to work with lapped riders ya know.


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## iliveonnitro (Feb 19, 2006)

Creakyknees said:


> what? really?
> 
> you're allowed to work with lapped riders ya know.


No you aren't.


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## chase196126 (Jan 4, 2008)

iliveonnitro said:


> No you aren't.



Im pretty sure you are. For example: 

3D4. Riders on different laps may work with each other except that no rider may drop back to assist a rider who has broken away from the field [disqualification for accepting such assistance].
http://nencycling.org/crit_rules

That is just one example I have found. From every race I have ever entered if riders who are lapped are not officially pulled from the race you are allowed to work with them. I lapped a crit field solo in France this past summer and I was well within the rules when I worked with my team mate to try to get him 2nd place. The exception to the rule is as above, you cannot drop back to help a rider(s) lap the field.


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## asgelle (Apr 21, 2003)

iliveonnitro said:


> No you aren't.


The things people think they know.


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## Andrea138 (Mar 10, 2008)

Yeah, well, I didn't feel like I needed her help


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## Creakyknees (Sep 21, 2003)

Andrea138 said:


> Yeah, well, I didn't feel like I needed her help


she couldn't have held your wheel for long anyway.


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## MR_GRUMPY (Aug 21, 2002)

Proposed rule change for next year........

http://wicycling.org/media/legislation 2010 final version for meeting.pdf


UR09.25 3D4 Dropped riders in criteriums - Jim Patton
Replace current rule with new wording.

(old)
3D4. Riders on different laps may work with each other except that no rider may drop back to assist a rider who has broken away from the field [disqualification for accepting such assistance].

(new)
3D4. Lapped riders may rejoin and work with the field, but may not work with break away or chasing riders [disqualification for accepting such assistance from a lapped rider].


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## Creakyknees (Sep 21, 2003)

thanks Grumpy, hadn't heard of that one.

not sure it's really needed... plus it's going to be one more thing for the officials to worry about when they should be watching other things.


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## MR_GRUMPY (Aug 21, 2002)

Did you also read about the proposed rules on junior gears? Looks like they're going back to two groups of gears..

Note: "proposed"


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## Creakyknees (Sep 21, 2003)

yeah I read the whole thing. nothing too earth-shaking, some good clarifications.

note the video camera ban... interesting


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## iliveonnitro (Feb 19, 2006)

MR_GRUMPY said:


> Proposed rule change for next year........
> 
> http://wicycling.org/media/legislation 2010 final version for meeting.pdf
> 
> ...


Andrea was on a solo break and one chick got dropped. She was working with the breakaway (=Andrea).

PS lapping the field to work with teammates FTW.


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## MR_GRUMPY (Aug 21, 2002)

new)
3D4. Lapped riders may rejoin and work with the field, but may not work with break away or chasing riders [disqualification for accepting such assistance from a lapped rider].

I wonder if this means that a dropped rider may grab onto a break (and just sit in) and use the break to tow themselves back to the pack????
The wording is still not very clear.. Why don't they just say that dropped riders "may not join or work with break away or chasing riders"


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## kbiker3111 (Nov 7, 2006)

Creakyknees said:


> note the video camera ban... interesting


That ticks me off. Last year the local officials really started cracking down on helmet cams as 'loose equipment'. I don't have one, but it was fun when I got to see some of the races I'd done on video.


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