I am trying to figure out best bang for the buck for fast disc wheels and was wondering if there are any studies comparing the dimpled Zipp to HED and RENN? I have found old studies including non-dimpled Zipp and HED but nothing more current and nothing on the RENN. Also, has anyone had bad experiences with the RENN (premature failure, quality issues, or just perceived to be slow)? Old studies of HED disc indicated it was very aerodynamic however the HED discs are pretty heavy. Zipp and high end RENN are fairly light but the RENN is quite a bit more affordable. Another option is wheel covers but I do not know if they are truly comparable for aero drag and how total wheel weight of a covered wheel would compare to one of the real discs. There may be other negatives to using wheel covers…? If I used wheel covers, they would probably be used on an 06 QR Caliente that I have been drooling over that come with Real Design 60 MM wheels. Pragmatism might prevail tho and I could go for a left over 05 QR Tequila at a nice price (but maybe could justify more money for wheels such as Zipp 909s).
The most telling comparison is on Kraig Willet’s pay site. It compares a CH Aero cover against a Zipp disc in a wind tunnel.
I really really really doubt there is much difference in the aerodynamics of most disks. Zipps dimples may give it an edge and who knows the raised junction where the aluminum braking surface is glued onto the RENN or HED may end up causing more drag or even acting just like the Zipp dimples. Zipp does have a leg up on bearing smoothness though, and sexiness and lightweight for sure.
If I was buying a disk for time trials or tris I’d consider price first, sexiness second, and aero data if there is any last. I think the Zipps are cool but bang for the buck I really don’t think you can touch the Renn. CH covers are cool too but you might loose a little of the stiffness that makes a disk so damn fast feeling. This is pure speculation of course, but also if you’re using CH covers put them on a lightweight shallow rim. Covers over a 60mm deep rim is almost redundant and just adds extra weight.
I think the hub on my 575 disc is way better than the hub on the rear Hed H3. It just feels smoother when spinning them in my hands. Not very scientific but I’m impressed with the quality of the Renn.
DAve in VA
Would you be willing to share anything from that pay site with the rest of us? What does it say? Should we buy it?
best bang? follow Cerveloguy and get the cover.
coolest? foget get Zipp, get the white Campy.
practical? Renn
I can’t speak for Zipp or HED, but the customer service from Renn is absolutely amazing!!! Bought a used Renn disc which FedEx decided would look better with a nice round hole in it… I thought the disc was basically trash, but decided to check with Frank Renfeldt if maybe the hub would be salvageable and replacing the actual disc part… Frank said that the disc can be repaired and offered to do it for FREE!!! Not only that, but HE PAID for the shipping back! AND he replaced the stickers so they cover the repair, making the disc look like new! If I ever need another disc (unlikely since the Renn is near indestructable), but I know what I would buy…
When you pay to see the data you have to agree not to disseminate it.
Styrrell
Ok but can you at least tell us if it was worth it… in your opinion?
Never read it.
Styrrell
It costs so little it’s worth it.
A disc won’t make you all that much faster than a good training wheel. Now compare a 60 mm rim to a disc and you’re talking a few seconds/hour. Now compare discs - no difference (or at least none that you or anyone else will ever detect).
Don’t waste money on a disc if you have decent race wheels (60mm). Most of us should never even buy race wheels period.
If you have a ton of extra cash and want something - go ahead and buy it but realize that a “great” set of race wheels (like 909’s or a Hed 3 front/Renn disc rear) will get you maybe 1/2 mph if you are lucky. The disc accounts for less than half of that…and thats compared to mediocre training wheels.
My friend has a Renn - I have 909’s and Alps…I’ll be playing around with some of my other friend’s sets (Hed 3’s) next summer when the weather gets nice again.
Dave
I just raced IMF with my Renn Mediera rear disc. It is so flexy that any out of the saddle work would result in the rim rubbing the brake pads. PLUS Frank lost my original order and it took countless phone calls over the course of three months to finally extract the damned thing from him.
My advice? Stay away from Renn.
My 909’s make me sooooo much faster…
HIM 2:36 vs. IM 6:10 using a 404 rear…
of course I’m only joking… I didn’t try to hammer a IM bike…
I just did a spin in my hands test between my Zipp404 and my Renn575 and I can tell you that the Renn feels a lot smoother and spins longer. I know that's not science but all I can say is "No wonder it's so fast!"
"Would you be willing to share anything from that pay site with the rest of us? "
The cat is more or less out of the bag, but I can’t give the info specifically because it’s Kraig’s intellectual property, meaning he wants those of us who have paid for the info to keep it quiet. For a small fee you can purchase this and a number of other good test results. He also has an interesting test comparing the different one piece aero bars in the wind tunnel. That’s also a good purchase if contemplating buying a one piecer.
I just raced IMF with my Renn Mederia rear disc. It is so flexy that any out of the saddle work would result in the rim rubbing the brake pads. PLUS Frank lost my original order and it took countless phone calls over the course of three months to finally extract the damned thing from him.
My advice? Stay away from Renn.
I’ve had a madiera since august used it in ironman canada(sweet especially with the cross winds and downhills) haven’t had a problem doesn’t flex and I’m 165 pounds. Used it at ironman florida no problems there either my previous disk was hed
superlight I like the renn much better.
CH Aero cover on a Mavic Open Pro rim laced to a PowerTap SL. The best of all worlds!
I appreciate all the good feedback. I will consider buying the suggested analysis because the price is fairly reasonable and it would be good to support the people that do this research. Sounds like the RENN is considered a good choice by most. I do want a disc as an option (when there are low winds and not too hilly type courses) because a minute can make a real difference in my age group, at least in last year’s 5K 30k 5k DU races I competed in. I have a front HED 3 already that really seems faster than my training wheels. The data for sale might suggest I consider a wheel cover, otherwise, the RENN is pretty lightweight plus you have the option of getting a clincher for about 80 grams of extra wheel weight. Clincher vs tubular is probably a controversial topic, but there is what appears to be pretty convincing analysis data that indicates a good low resistance high ply clincher has significantly less rolling resistance compared to tubular.
This is supposedly due to the tubular glue frictional losses, that are not overcome by higher tubular air pressures.
“”“(when there are low winds and not too hilly type courses)”“”"
With today’s discs, you can still run a disc wheel on hilly courses, you’ll gain mre speed overall than you might lose going uphill. The windier the better for a disc, IMO. I’ve never noticed any problems in 30mph side winds and I ride a softride.