What am I missing here? Each 28 spoke wheel expends 30+ watts more than the carbon wheel at 50km/hr(nearly the target speed of 52 km/hr for the record attempt),according to Norriss' data.. That an expenditure of 60+ watts above the carbon wheels just to churn the wheels through the air.That would be a significant percentage of the riders power output at the record attempt speed.Or would it not? Wish I hadn't ogled that cute blonde during this part of the college physics lecture. Art Link,San Antonio,TX
Jan Heine <heine94@earthlink.net> wrote: Date: Tue, 25 Sep 2007 17:14:20 -0700 To: norris.lockley@talktalk.net, classicrendezvous@bikelist.org From: Jan Heine <heine94@earthlink.net> Subject: Re: [CR]Now..Wheel aerodynamics ...how to get indisputable data..
At 12:42 AM +0100 9/26/07, Norris Lockley wrote:
>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.
>
Considering that a recreational rider on an on-topic bike will put out about 150 Watt at this speed, the 6.6 Watt saved isn't all that significant... About 4% of your power output. And that is on a very aero bike where the airflow was very good everywhere else. On a standard road bike, your gains probably are smaller - the figures I have seen 2-3% improvement in aerodynamics, not power output. If we go to the wind tunnel again, we may try to test an aero wheel... even if it's off-topic for this list.
When you compare that to the - on-topic - power savings by using classic tires with cotton or silk casings...
Jan Heine Editor Bicycle Quarterly 140 Lakeside Ave #C Seattle WA 98122 http://www.bikequarterly.com _______________________________________________
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