Re: [CR]Tyres aerodynamics debate, how to get undisputable data.

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Date: Sun, 23 Sep 2007 18:26:26 -0300
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Subject: Re: [CR]Tyres aerodynamics debate, how to get undisputable data.

It is so very easy to collect data today on this topic, experiments have no doubt been done thousands of times by amateurs. And thousands more by every professional racing team. It doesn't even require on-bike data recorders, but they have been available for <$300.

Don't trust the rider to be constant between trials? How about using gravity? A spreadsheet, some tyre changing irons, an air pump, a pressure guage, and several tires to switch between. A cyclometer would be nice. Several $15 stopwatches borrowed from the summer swim team will help. Record time vs distance for several points, and apply a little secondary school maths and physics. Want to validate your model with different speed? Find a steeper hill. Heavier load? Sling a pair of partially filled sandbags (gently) over the top bar.

(For the inspired: Why bother to get your hands REALLY dirty changing the rear tires; just swap out front tires.)

said Harry, stirred by: nick Bordo <>'s message of: Sunday 23 Sep 07 at 10:38 PM, On: [CR]Tyres aerodynamics debate, how to get undisputable data. [echoed below, in part<=1] -oOo- I guess I shall be kicked for both too KOF and OT on this one, but there was some very thorough testing of bicycle aerodynamics done by some of the greatest racing on wheels engineeers in the world: the Lotus Formula 1 team.   That was for Chris Boardman's attempt at the hour record on his specifically designed carbon Lotus or am I wrong again and he only used it in the Barcelona Olympics, which he thoroughly dominated in the 4000m? You can safely assume that (I remember for fact reading that they did) put man on bicycle in a wind tunnel and worked at every factor they knew about, and I guess they knew a thing or two.   Were I to write to Lotus asking for their data, the best I could hope for would be a polite referal to a psychiatrist (plus I don't think there is a Lotus team any more). Maybe somebody with a reputation in the cycling world could write the people involved in the tunnel experiments ?   My point being that as far as pure aerodynamics go, the testing data is there, and maybe available. I guess those people also took into account all the other known factors implicated in high speed forward movement of the two wheeled contraption named a bicycle. On flat surfaces, at least.   Nick Bordo, Agen, 47000 France

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