Wheelbuilder.com releases windtunnel data for wheel cover

autospa1

Wheelbuilder.com has confirmed actual performance for disc vs zipp 404 vs 30mm alloy wheel vs 30mm alloy + wheel cover, and just in the knick of time! I had been contemplating racing my ZIPP 404 rear at IMCdA instead of the training wheel w/PT for performance reasons, and now there is scientific data confirming the trainer+wheel cover performs better at yaw angles > 6 degrees and similar below that.

 

Thanks wheelbuilder.com!

http://www.wheelbuilder.com/enewsle...Comparison

Tom Glynn

Very interesting data for sure. Looks like I'm sticking with my covers!

tom

John Stark

 $85 or $2,000?  Hmmmmm . . . .  . . . .   Plus you can put the cool stickers Tucker has crafted on the wheelcover.  :-)

 

Here is a shortened link:  http://bit.ly/lMxUwT

JOhn

 

David Ambrose

Can't someone do a test under more realistic race conditions? This test is at 30mph. Since most AGers race somewhere between 18-22mph, it would be much more meaningful if tests were done at these speeds.

Coach Rich

I know that Rich did this test (or at least "a" test) quite a while ago at the wind tunnel in San Diego. I know he's been sitting on this data for a while and it's nice to see him putting it out there. There was a thread on ST about it a few minutes after he sent the email and I wrote him an email about what he needed to do with that thread to boost his thread. Threatened to kick his ass if he didn't do it yesterday, he didn't, so looks like I stopping by his shop later today to punch him in the nose.

I'll ask him about the 30mph thing when I see him, riding with him tomorrow in the mountains.

[Deleted User]

I'm not up to speed with grams of drag and yaw angles. I am doing my first IM at Lake Placid this year. I have been training with and will race with a power tap. Not sure what my bike split will be, but I am in the 200+ pound range, so it will not be blazing fast. Is a wheel cover a good idea for someone like me? What kind of difference, in time, could it make? I know dropping another 10lbs will be huge, and I'm working on that too...

mancona

regarding the 30mph thing, I've HEARD at least one windtunnel that is commonly used is setup to be used at 30mph which is consider low speed for wind tunnels. I've heard that the majority of wind tunnels are actually set up to go much faster as they are used for aircraft and automotive testing.

I also think alot of it has to do with wheels being designed for pro tour riders where 30mph is much more likely then for AG long course triathletes.

Also, I don't think it is that unrealistic as if you are moving at 20 mph but have a 15 mph cross/headwind, I would guess the actual wind speed the air hitting you and the bike is closer to 30mph depending on yaw angles of course.

Until an indepentant 3rd party with no stake in any of the products does the full test, I wont fully trust it. Even then, things like tire choice become critical... as some wheels work better with certain tires.

Paul Hough

@ Matt - what are the best tires for regular Zipp 404s?

William Jenks

@Matt and others.. I think the point to take from this is that the disc-cover and the disks are comparable. You're right - there are tons of details that would lead to small differences (that could conceivably add up) based on tires, yaw, wind velocity, etc.

Bottom line for me = disc cover is very, very, very similar to disk and much lower cost. That's what I need to know. :-)

kurshing

@Jim - in all honesty, the wheel cover is PART of your speed equation. Yes, as you said, weight makes a big difference, 10 pounds especially. Body position is the next biggest thing...if you are a sail on your bike, the wheel cover won't matter. Studies show that an aero helmet is a big difference maker as well.

As far as the wheel covers go...any difference one might make, considering the cost of $85/$95 + shipping, is probably worth it. Rear disks and race wheels work like exponents...the bigger the average speed, the bigger the difference they make.

I just got one and I am racing on a PT as well...not sure why I haven't gotten one before!

mgraffeo

Stephen, just a quick correction. Aero gear has a bigger impact in drag reduction the faster you go. However, the time savings is bigger for slower folks, as they are out there longer. cervelo had a great writeup on their site a few years ago, but I don't still have a link to it.

[Deleted User]

Interesting info Stephen and Mike. Thanks. Seems like for less than $100 not much to lose.

Carl

I ride a cervelo P3 with a rear wheel = DT Swiss RR 465 Rim. I measured the clearance off the cogg and yes there is greater than 5mm and according to there website my wheel is compatible with the cover. Well when my chain is in the lowest cogg (12-25) it rubs on the cover. I have called them and we have visited and there is no quick fix. Tried having the rear derailer adjusted but there is too much play either on the high end or the low end and the chain starts to fall off or jump gears. JUST SOME WISE WORDS....THAT WHEEL AND CERVEL0 P3 ARE NOT COMPATIBLE WITH A COVER!!

mancona

@William - I agree 100%, in fact I sold my Zipp disc about 2 months ago and raced at oceanside on an 808 with cover. The small differences between different types of disc and wheelcovers is lost in the nosie anyway. The main reason I sold mine is it just isn't worth the money (even at a discount) to have an 808 rear and a disc.

@Paul - that depends on which 404 and what is important to you (i.e. aero, rolling resistance, wight, ride quality). For alloy clinchers the closer you can get to a 19mm tire the better as far as aero and the Bontrager Aero Wing TT 19mm is a great tire if you can find it. For tubies, firecreast tubies, and firecreast carbon clinchers, Zipp claims that a 21 will test to be the most aero and that there is very little lost by going with a 23. Of course Zipp says they firecreast shape was desiged to work best with their tangente 21s. I am personally running a tangente 21 in front and a 23 in the rear, per Zipp's recomendation for long course racing. However I'll likely go back to the vittoria CXII next, as they are almost the same tire for less. If you really want aero, the Bontrager R4 Aero 22 fits great on a firecreast clincher.

neilmacd

@Carl - I ride a P3 with a Mavic CXP-33 PowerTap rear, and a SRAM 12-28 cassette, and have had no interference issues with my wheelcover with that combination.

Paul Hough

@ Matt - I have 2010 alloy clincher 404s. Are you suggesting 19mm for front and back or front only? I thought the latest thinking was that wider is better?? r/Paul