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Old 08-27-2009, 06:08 AM   #11 (permalink)
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drafting drag seems to assist both

All articles in the cycling forums contend that drafting assists both.
Seems that up to 40% energy saving by the following rider is quoted in many posts.
For the leading rider the only numbers I can find are here http://forum.simwe.com/archiver/tid-818221.html which show a reduction in the drag co-efficient from 0.285 down to 0.277.
These drag co-efficients seem awfully low for bicycles, which are generally quoted up around 0.8. The post doesn't provide any other details of the experiment, such as the speed, frontal area or rolling resistance. By my calculations, at 55 km/hr it reduces the lead riders power by 6 watts, from 361 to 355 watts (< 2%), or increases his/her speed by about 0.4 km/hr.

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Old 08-27-2009, 11:52 AM   #12 (permalink)
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ROFL - I think you're correct on that, after thinking it through more. Thank you.
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Old 08-27-2009, 12:09 PM   #13 (permalink)
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I think we'd have to distinguish between close drafting, and "less-close" drafting.

If you're close enough to physically occupy the low pressure zone behind the lead vehicle so flow off its top & sides attaches to the front of the following car, then both may benefit.

But if the following car is simply driving in the detached/turbulent wake of the lead car, as I believe the BMW was doing a couple of car lengths back) then it's still enjoying some benefit (yes, a smaller one than the bumper to bumper scenario), but in that case the lead car would see no gain.

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