http://www.timetrial.org/aerodynamics.htm

Because of the changes in atmospheric conditions (wind, temp, pressure, etc) during a 5+ hour ride it would be pretty tough to quantify the time savings a disk would provide at IM Wisconsin. However, I think it is not irresponsible on my part to throw a guess out there like 4-6 minutes over a pair of 60mm deep rims such as 404's. Again, no more than a Scientific Wild-Assed Guess (SWAG). Could even be more depending on how fast you are.

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Tom Demerly
The Tri Shop.com

Thx Tom, sounds like a pretty good guess. Did you read the bottle holder study in Triathlete this month. They claim, that behind the saddle mounts may cost you 3 min. Sound quit high when you compare it to the benefits of a disk.

For well under three and a half bills, the Renn is the absolute best disc out there. Why? Because you get the benefits of a disc for a fraction of the price of the nearest competitor.

Frank makes no junk for the price. His mission is to bring the field a lot closer together for a lot less money. Fit, finish and trueness is something I've never seen at this price. There's no reason why you should pay any more for a disc wheel when the Renn is such a good deal and a high-quality wheel, as well.

Besides- you'll end up faster as you'll work less to pay for a Renn. How much overtime would you work for a Zipp or a Corima?

Well gents, this abstract doesn't detail the testing protocol, but the results are fairly surprising. I'm waiting on someone to send me other articles and abstracts supporting this point of view. If true, all those $$ we spend on wheels aren't doing much more good than making us look prettier.

http://www.ncbi.nlm.nih.gov/...20&dopt=Abstract

All discs will do about the same thing. There might be three or four seconds between them depending over 40 kms whether flat, lenticular, dimpled, etc. The few hundred grams in weight between different models has a minimal effect on performance. Renn is so popular because of the great price. The cheapest possible functioning disc is just find a set of CH Aero disc wheel covers and a box rim off ebay. The most important thing with disc covers is to make sure the seal around the circumference of the rim is good. A $.98 roll of black electrical tape takes care of this problem. It may not look as pretty as a new Zipp but is just as functional and costs about a grand cheaper.

Here's Jim Martin's opinion based upon his wind tunnel testing

http://home.hia.no/~stephens/aero.htm