Can anybody point me towards such data, or even to some data for the Blackwell alone?
As I mentioned in the P4 thread, I’ve got wind tunnel data comparing a Blackwell 100/flat disk against a Zipp 808/bulge disk, and the latter proved to be significantly faster. Since the wheels were tested as pairs, though, it would be easier to interpret the data if I knew how the Blackwell 100 behaved as a function of yaw.
not sure about test results, but no way is it faster than an 808 at significant yaw, i’d put money on it.
have you ever looked carefully at the shape of a blackwell 100? calling it a primitive shape is a big understatement. the sidewalls are *perfectly flat *(i.e., perfectly vertical) for most of the rim depth (we’re talking at least 80-90 percent of the rim depth), and then only at the leading edge of the rim do the sidewalls curve slightly to meet the other side. very cheap to produce, maybe passable drag numbers at 0 degrees, but i very much doubt good numbers at 15 degrees.
not sure about test results, but no way is it faster than an 808 at significant yaw, i’d put money on it.
As I said, it wasn’t, at least when tested in combination with a flat disk. If I could track down some data for the Blackwell 100 (also, I believe, sold as the Planet-X 101) by itself, though, then it might be possible to make some guesstimates as to how much of the difference was due to the rear wheel.
how did you correct for Crr differences between tub and clincher?
I’m sure that John Cobb would have something to say about your (clearly) educated opinion.
I’m sure that John Cobb would have something to say about your (clearly) educated opinion.
Well, what John might tell you after picking you up at the airport and taking you to lunch to kill some time while waiting for the wind tunnel folks to finish with their prior clients is that between patent issues and up-front development costs, it is very hard to come up with something just as fast as a Zipp, but that didn’t stop him from working very hard to try to refine the “nose” of the rim…or something like that. 
Well, I will say that I am interested to see what you find for the Blackwells, but that being said, I am STILL going to run my Blackwell Disk and 100mm front /or my 50mm front. Why? because I purchased the 3 of them for $1200 less than what it would have cost me to buy a Zipp Disk and 808. So I can live with being marginally slower with less developed Blackwells. (Again, though, I am interested in your findings)
I am with you…i am sure Cobb made sure it was FAST stuff, fast as everyone else who knows. I got it for less than the over priced ‘other’ wheels as well.
tfun~
Heaven forbid
but I run a BW100 and … an old Zipp disc without dimples. I’m soooooooooooooooooo slow with that wheel set : (
I am interested to see what you find for the Blackwells
Not find: found (data were collected in June of 2007).
there’s this here (I believe the ‘101’ is a Blackwell). According to the Zipp guy, this was with a Corsa 21. I have to imagine that with a 19mm Veloflex, it’s probably a little better since it seems to mate with the rim perfectly.
Thanks - that is exactly what I was hoping to find, but was too lazy to dig for myself.
Do you recall d the direction of the yaw sweep over which these data were collected? We went 0 → 2.5 → 5 → 10 → 5 → 2.5 → 0 deg of yaw, and there is some hysteresis with the Blackwell wheels (but not the Zipps) on the bike.
It also would be good to see how the H3 would improve with a 19mm tire, too; keep the tire as a constant really doesn’t work all that well (unless one was measuring crr), as each wheel is designed with an optimal tire width in mind. Putting a 21mm tire on a wheel designed for 18-19mm tires isn’t a good comparison; it would be like putting a 25mm tire on an 808, which should be wide enough to fall outsise of Zipp’s ideal tire parameters (21-23mm)
See? Now THERE’S someone who understands the phrase “appropriate width tire”! 
Keeping the tire width constant is a great idea when the purpose of the test is for marketing spin…
Kevin
Why is it that we think the 101 is a Blackwell? John has been very clear about the Planet X and Blackwell wheels being different in the past. If it were really a Blackwell, wouldn’t they have called it a 100?
Chris
different by 1 millimeter perhaps?
deep dish aero wheels aren’t that complicated. If you have the torridial shape you can tune a sweet spot at a certain yaw angle, if its flat you can’t.
exactly as this represents.
perhaps there is an as yet undiscovered 3rd way to go about this, but if so nobody is currently doing it.
Why is it that we think the 101 is a Blackwell? John has been very clear about the Planet X and Blackwell wheels being different in the past. If it were really a Blackwell, wouldn’t they have called it a 100?
Chris
John did what he could within the law and his own knowledge. That may or may not make it any better than the Planet X 101, but it’s not hard to imaging that he could come up with something to bring the Blackwells into the acceptable range at least.
Chris
John did what he could within the law and his own knowledge. That may or may not make it any better than the Planet X 101, but it’s not hard to imaging that he could come up with something to bring the Blackwells into the acceptable range at least.
Chris
If “acceptable” means “close to 808 performance”, then AC’s tunnel data shows that didn’t happen…
Actually, I meant more along the lines of “Better than anything else NOT made by Zipp or HED and covered under the toroidal patent”
Chris
.
John did what he could within the law and his own knowledge. That may or may not make it any better than the Planet X 101, but it’s not hard to imaging that he could come up with something to bring the Blackwells into the acceptable range at least.
Chris
If “acceptable” means “close to 808 performance”, then AC’s tunnel data shows that didn’t happen…
OTOH, Zipp’s data shows a 101 mm deep rim beating out both a 404 and an H3…so assuming that is the same as the Blackwell 100, perhaps John didn’t do so poorly after all.