Re: [CR]Now..Wheel aerodynamics to get indisputable data..

(Example: Framebuilding:Norris Lockley)

Date: Tue, 25 Sep 2007 21:12:57 -0700
From: "Kurt Sperry" <>
Subject: Re: [CR]Now..Wheel aerodynamics to get indisputable data..
In-Reply-To: <>
References: <>

I'd be most interested in any details of the testing methodology employed to arrive at those figures. Was this done with both wheels? Was this done with the wheels on a bike? If so, with a rider on and pedaling? If both and done in a tunnel, was a moving floor used? Were the effects of real world cross winds considered? Was the testing done involving transients or steady state? Etc. Etc.

Is ther any empirical data to show that a "stiffer" wheel is more efficient at transmitting tractive power? If so, what methodology was employed to get the data? Again, did these data represent or include transients or steady state conditions?

Kurt Sperry Bellingham WA USA

On 9/25/07, Norris Lockley <> wrote:
> Urged on by a batch of encouraging emails received off-List, I spe
> nt some time today ransacking my office in the hunt for the wheel testing
> d
> ata produced for CORIMA..and eventually Chris Boardman. Luckliy the page
> fu
> ll of statistics noted down by Pierre Martin the President of CORIMA was
> qu
> ickly found.
> The research was headed "Puissance Consommee d'une Rue" - "the Power con
> sumed by a Wheel"
> The two wheels tested dynamically were on the one hand a 700c/28"p
> rofiled aluminium rim ( think MAVIC Open Pro or similar) with 28 spokes
> and
> on the other a CORIMA 4-spoke carbon wheel of similar diameter.
> The tests showed that at a speed of 30kms/hr, the standard alloy racing
> wheel consumed 12.6 watts, whereas the CORIMA only used 6 watts.
> At 40 kms/hr the standard wheel used 30 watts, and the CORIMA only 14.3
> watts.
> At 50 kms/hr the standard wheel used 58.5 watts and the CORIMA, less tha
> n half that at 27.5 watts.
> The power output of Boardman had been measured at around 470 watts..ther
> efore the idea was to equip his bike with wheels that would expend as
> littl
> e as possible of that output, in order to help him stay the full course of
> the Hour Record at a calculated speed of 52
> The added bonus is that the carbon wheel is stiffer than the standard al
> loy one and is therefore able to transmit the drive through the back wheel
> more efficiently
> I have quite a collection of photos, tests, drawings, autographs linked
> with Chris' World Record ride...and they are all just stored away in
> a cardboard container. seems a shame somehow.
> Norris Lockley, Settle UK..on the verge of drowning in nostalgia.
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