We ran some tests last week to illustrate drafting, and thought you might want to see the results. The CdA was measured with our Track Aero System at the VELO Sports Center.
The test:
Here’s what the CdAs do:
http://imgur.com/iy2XCqH
Note: The CdA traces (red and turquoise) are in the bottom graph window.
Clearly I need to draft behind a bigger guy!
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Great stuff Andy!
What was the draft distance and height of each participant?
Hugh
So that’s why I look like “dinnertime” to the little guys. What was the approximate distance between riders? Do you perhaps have three and four rider trains planned?
Did you see Shaun Wallace’s idea about putting smaller riders on bikes with higher BBs for team pursuit?
Awesome stuff.
Is that road position or aero?
~Greg
Can you post all the data? Looks very interesting.
-Robert
Oh great. Now we can expect to see even more drafting going on at IM races.
Did Tom Rodgers lend his “expertise” as a drafting test subject?
The bigger guy still gets a pretty decent benefit, it seems.
As others have stated, what are the distances? I’d love to see the difference at draft legal distances (4+ bike lengths).
Thanks!
Awesome stuff.
Is that road position or aero?
~Greg
It was road.
The bigger guy still gets a pretty decent benefit, it seems.
As others have stated, what are the distances? I’d love to see the difference at draft legal distances (4+ bike lengths).
Thanks!
Pretty close. I’d say about 30-50cms, on average.
Can you post all the data? Looks very interesting.
-Robert
I would love to, but I can’t. 
Did Tom Rodgers lend his “expertise” as a drafting test subject?
His type are the reason I asked Jimmy for recourse. Having talked with Andy for years now, and seen some of this data before, the benefit drafters get can be quite predictable. At Cozumel last year, a Texan AG winner magically biked 30 minutes faster. Like you, I exchanged words with the drafter. FinisherPix documents the draft pack. Unsurprisingly, the racer’s Kona bike split is an hour slower than the Cozumel draft-inhanced split.
It would be helpful to have some numbers and not just the graph. I think the graph is a little misleading. It looks to me like the delta for each rider is about the same when going from non-drafting to drafting. It is just that the big guy has a much larger CdA. So something like:
Non Drafting Drafting
red .25 .20
turq .28 .23
When you put them next to each other (.25/.23) and (.28/.20) it looks like the benefit for red is huge .08! while the benefit for turq is small at .02, but this is misleading, the benefit for both is .05.
Am I missing something?
Any data for when they ride alone?
(Thinking of these results: http://www.trainingandracingwithapowermeter.com/2010/04/does-drafting-benefit-leading-rider_23.html)
Any data for when they ride alone?
(Thinking of these results: http://www.trainingandracingwithapowermeter.com/...eading-rider_23.html)
No, that would make it complete, wouldn’t it?
Andy, when the Milton Velodrome opens and I get a chance to spend some good time on it, I’ll be doing stuff like that. In the meantime, everything I’ve posted has been paid for by someone else. I have had to ask for permission to post it.
Any data for when they ride alone?
(Thinking of these results: http://www.trainingandracingwithapowermeter.com/...eading-rider_23.html)
No, that would make it complete, wouldn’t it?
Well, a bit more interesting, anyway. I mean, don’t we already have a good quantitative understanding of the benefit of drafting?
Any data for when they ride alone?
(Thinking of these results: http://www.trainingandracingwithapowermeter.com/...eading-rider_23.html)
No, that would make it complete, wouldn’t it?
Well, a bit more interesting, anyway. I mean, don’t we already have a good quantitative understanding of the benefit of drafting?
http://www.ncbi.nlm.nih.gov/pubmed/2318782
http://www.ncbi.nlm.nih.gov/pubmed/10589873
Yes, we do. But Slowtwitch is about rehashing the rehashable. 
Besides, the little wiggly plots are more fun.