Interesting results since the disk combos seemed slower. My German-speaking capabilities are non-existant so I’m not entirely sure of how they were tested but it looks like riding on a track at a constant speed with a power meter. Any thoughts on how valid this test would be for riding out on the roads and in crosswinds? I was really surprised with the Nimble results.
I have a hard time believing that Xentis is planting this. If you look at the results they didn’t do that great. I’m actually surprised to see they have it on their site at all.
One question that comes to my mind, is that given the high variability of sew ups (handmade construction, performance is dependent on gluing technique, etc.) how do they normalize the rolling resistance between each wheelset?
Only a handful of watts separate many of these wheels, I’m a bit dubious that the margin of error is low enough to permit that level of comparison. Also remember that on in indoor track that there is no ability to compare the effect of crosswinds.
The other thing that is strange if you look is that the Xentis was in essence the same as the 808s, but it’s 1,000 Euros more. Doesn’t seem like a good deal to me. But things like crosswind stability also play a big role in wheel selection. Does anyone else know anything about those Vueltas? Those are nice looking wheels and the price is certainly nice. I know Colnago uses them on some of their higher end bikes, but I can’t find much other info on them.
The report mentions that the tests were carried out at the same tire pressure using the same tire. The reason for choosing a test speed of 45km/hr is, they say, that rolling resistance (or the difference in) is negligible (when you look at the total drag) at this speed.
The report mentions that the tests were carried out at the same tire pressure using the same tire. The reason for choosing a test speed of 45km/hr is, they say, that rolling resistance (or the difference in) is negligible (when you look at the total drag) at this speed.
Didn’t Faris ride Xentis @ IMH?
Well, I’d presumed that they would at least do the minimum reasonable step of using the same model tire and pressure. My point is that even with the same model & brand tire that because sew ups are handmade, they vary much more in roundness and straightness than clinchers. In addition, I’d bet you could install the exact same tire several times and the rolling resistance could vary measurably due to differences in installation, such as straightness and roundness, and quality of glue bond.
I would expect that it would be totally impractical to install the exact same tire on each wheelset, and even if they did this that the rolling resistance would vary, think of the glue build up on the tire after multiple installations. OTOH, it would be entirely practical to install the same clincher tire on different wheelsets for testing, assuming that the overall mileage is low enough that wear wouldn’t introduce significant variation.
I also think the assertion that rolling resistance is negligible at 45 km/hr is highly questionable.
I would expect that it would be totally impractical to install the exact same tire on each wheelset, and even if they did this that the rolling resistance would vary, think of the glue build up on the tire after multiple installations. OTOH, it would be entirely practical to install the same clincher tire on different wheelsets for testing, assuming that the overall mileage is low enough that wear wouldn’t introduce significant variation.
I meant to say tire type, not the exact same tire. Sorry for the confusion.
It’s essentially a Zipp 404 with variably-bladed spokes and different hub. Curious how it might compare to a regular 404 from Zipp, to show if those spokes have any effect.
Another German mag Tour, did a test where they found the Xentis to perform quite poorly. It shows that the Zipp 808 was 2nd only to a disk, while the Xentis showed “untypical behavior” and that drag increased with increasing stream angles. The article is on ZIpp’s site (of course), go the the Tour Mag Aero test and open page 4. My only point is that some tests may show 1 wheel to be far superior, where another test with different protocols and people performing that test will show the same wheel to be a rock. From the little I know about the mag that did this test, they are supposedly the most independent and care only about true results, not making advertisers happy. All the wheels on the market today are so close, can it be that one is the Holy Grai? Choose your wheel on your budget, the courses you race on and maybe the cool factor. The only wheel I can see that could claim that title of best aero wheel would be the Lightweight’s. Are they really THAT much faster? Probably not, but carbon hubs, kevlar spokes and the unique factor make them the best in my book. No, I don’t own a pair either.
Here’s some info: