Here is the data from the latest Tour Germany wind tunnel test…since everybody is always looking for unbiased sources for this stuff. The 808 again does very well, but the new Xentis TT specific wheel has made huge progress after being called one of the slowest wheels in the 2005 Tour test, they redesigned the perimeter of the wheel to be almost identical to the 404 shape (60mm deep with hybrid-toroidal cross section) This is also the first ever data I’ve seen on the Roval or new Mavic Cosmic Ultimate wheel, both of which were unavailable when we were last in the tunnel in Feb of this year.
Do you think the tour data is consistent with your own ‘in house’ data?.
anybody want to offer up a good translation?
the chart, at least, is readable. what is amazing is how well the 808 does at higher x-wind angles …
I believe it says “Zees Zipps eees fast. Zay make you go a voom-voom.”
Of course I might have mistranslation, those damn tricky umlauts and whatnot…
Bob
This is remarkably accurate to our data that we publish on this wheel. When we first started publishing data on the 808 we were using the same wind tunnel protocol that everyone else was using, where you start at 0 and yaw outward taking data, but we realized in 2004 that if you yaw out to 20 or 30 degrees and then take data coming back, there is a pretty sizable hysteresis gap between the two data sets (you get the identical phenomenon with aircraft wings if you take them past their stall angle) We have subsequently changed our protocol to use the 30-0 data instead of the 0-30 protocol after finding that unless you take the wheel all the way back to 0 and let it stabilize, the wheel will continue on the 30-0 curve and not the 0-30 curve, which tends to predict lower drag. This is how you see lens disc data with negative drag, on the old protocol, this would happen about 1 in 3 runs with that type of wheel but was not consistent, after switching to the new protocol we had not seen negative drag in over 200 hours of tunnel time until we had that negative 80 with the disc prototype this february, it was particularly exciting as we had all assumed that negative drag was essentially not possible on the new protocol, and we repeated that data point 2 more times to make sure.
Anyway, if you look at our white paper data, the stall angle of the 808 is shown at 15 degrees, which is using the old protocol, the new data we have produced and published predicts stall at 12.5-13.5 degrees depending on the tire you are using…this matches the data shown here almost exactly, and I know that they are using our new protocol at the suggestion of the guys at the wind tunnel. This also matches very closely to the Tour magazine 2005 data where the 808 actually beat out a disc wheel at almost every angle below 12.5 degrees.
Here’s the Tour data from 2005: note that both the Ritchey and Easton are using non-dimpled 404 rims
This would be testing wheels alone, with neither rider nor bike? Are the wheels spinning?
Is that a fair / valid test? I would think that testing wheels alone tends to exaggerate differences between wheels; put a bike around the wheel, and the differences may not be as pronounced. Put a rider on the bike, and some of these differences become absorbed into the margin of error for the wind tunnel apparatus.
This all looks great and informative, but how serious should we take these tests when they never test Zipp products directly against HED. It’s odd that you openly brag that you’re the greatest while these tests don’t use all of your top competitors to compare to. There is no HED H3, Stingers, or Jets in this test. I would imagine that since they share the patent for toriodal rim shapes that they would test those wheels against zipps, and that would matter more so then testing a “Citec 600x”?!
Where do the H3 and Stinger 90 fall here? And why does Tour never test the HED’s(that I’ve seen)?
I’d suggest you stick to riding your H3’s. BTW I have a used pair sitting in my closet if you like to have those as well.
I’d suggest you stick to riding your H3’s. BTW I have a used pair sitting in my closet if you like to have those as well.
I need a front H3!
As mentioned, the magazine has never tested the H3, so it amazes me that so many people automatically assume the Zipp is the best without any available data.
Kraig Willet tested Zipp vs H3. The results are available for a nominal fee on his website.
I couldn’t agree more except to add that I’ve noticed this most recent Tour comparison only tested up to 15 degrees. Similarly, this translation and consolidation of the 2005 and 2006 wheel tests only included data for yaw angles up to 15 degrees http://www.rouesartisanales.com/article-4934445.html It is my understanding that the Hed 3 tests better than the Zipp 808 and the 404 at angles greater than 15 degrees.
On the other hand, the chart provided by jasonogk here http://forum.slowtwitch.com/gforum.cgi?do=post_view_flat;post=1174216;page=1;sb=post_latest_reply;so=ASC;mh=25; includes data for a wider range of yaw angles. I think it turned out that this data matched the data available on Hed’s website and, thus, likely came from them.
I really do appreciate that joshatzipp made the above test available to us here. However, I would have liked to have seen these wheels, particularly the Zipp 808 and the Xentis TT, tested at even greater angles.
I honestly have no idea what range of yaw angles are likely to be representative of real race conditions. I’ve read on this forum that the higher angles are less common the faster you ride. It would be great if someone could explain what angles are likely most common and under what conditions.
I don’t believe that Zipp has anything to do with determining what wheels this German magazine tests. Similalry it appears that josh also openly gave his opinion of the shortcomings of the test procedure which he didn’t have to do. I guess you should evaluate the tests for yourself and decide how much they help you make a decision. What obligation does zipp have to draw attention to unfavorable results? If you want to see a pretty comprehensive and independent series of tests you might need to do some looking on your own. a good place to start would be biketechreview.com they have a lengthy list of wheels they tested and will send you a report for a nominal fee. If you do find some other independent data I, for one, would love to see it.
Kevin
Keep drinking the Zipp kool-aide.
Ill take my HED Stingers any day.
Wasn’t automatic without real data. Like I said, “I have a used pair sitting in my closet”.
Yea Josh, What the hell were you thinking? Allowing those Germans to do some damn test and not include the wheels the folks at Slowtwitch want you to. Why is their data only for some speeds and wind angles? And why wasn’t the Mavic track specific front wheel included? Did they use those Tufos and their seat was too high? Are you just not thinking before you allow them Germans to do stuff?. Shame on you for bringing to light an article that wasn’t even in English, you have to do better than that. Now if two kids standing on each others shoulders, how many Cervelos tall are they anyway? Thanks for the article, my German is about as bad as my Italian but the translation of Zeem Zipps go vroom vroom looked pretty accurate to me.
Well my Nissan is the fastest drag racer in all of Staten Island- (errr, well, ummm, you see, people with Ferrraris and Porchses were not there to race therefor…).
So let me get this straight, its alright for an employee of Zipp to post an article purporting to compare the aerodynamics several wheels, which, due to the limited testing and the omission of some of their competition, happens to make his employer’s wheel look really, really fast, but somehow there’s something wrong with a few slowtwitchers pointing out that the testing could have been a little more more complete? Try another straw man.
I honestly have no idea what range of yaw angles are likely to be representative of real race conditions. I’ve read on this forum that the higher angles are less common the faster you ride. It would be great if someone could explain what angles are likely most common and under what conditions.
For IMNZ a southwest 10kph wind will give a 6hr rider an average yaw of just under 17deg.
Gives ~13.5deg for a 5hr rider
Usually the wind is not that strong - makes a wheel that is good over 20deg seem a bit less relevant (for that course).
Yes Rand, I do think it is allright for someone in the biz to say. Look here, this is an article in German about a wheel test they did with some aero wheels. Look, one of the wheels that they mentioned last time as the slowest aero wheel on the planet got a lot better. He didn’t pay for the test, or to my knowlege was not paid for the test. And he didn’t brag on his stuff.
They also omitted the Bontragers, Ambrosio XXL, Campy Bora, the Blackwells as well as HED and about three other Mavic wheels in their test. I think their lineup was a pretty good one on some current wheels…
I have a HED 3, HED 3 disk, a Zipp disk and a 404. I don’t believe I am one second faster on one set or the other. I apperciate Josh@ Zipp dropping in on our forum. Steve Hed, I am sure, is just as welcome to drop in and submit any article he finds in the Spanish paper or where ever his wheels are made these days. (Mine were from Spain) But hey why yell at Josh as unfair about an article he didn’t write? At least someone at Zipp cares enough about their coustomers to drop in and be available for comment. Yes I do know that Steve and Annie do have good customer service as well.
Edit, Then Cees drops in, wow what can I say. Good to hear from you sir, and my apologies for not mentioning no ADA wheels in there either.