# Roval CLX64 vs Zipp 404 in the tunnel....



## thumper8888 (Apr 7, 2009)

Has anyone seen any data on this besides Specialized cryptic marketing verbiage?
I keep trying to cross reference various tests because I'm pretty skeptical that the rovals are faster, but there's not a lot out there.
The main thing that seems missing is actual straight up comparison during the same test with at least a neutral observer present.
It makes me pretty suspicious when Specialized let Blather about Bikes in for lengthy tunnel testing with a host of different brands wheels and tires but but somehow conveniently left out the most obvious for comparison, the 404FC.
There is a British tri publication that tested them and several others and thoroughly panned the Rovals, but their test sounded like it was on an outdoor course and not very scientific at all.


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## MMsRepBike (Apr 1, 2014)

Knight 65 is faster than both.


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## thumper8888 (Apr 7, 2009)

*How could that possibly be?*



MMsRepBike said:


> Knight 65 is faster than both.


After all, there's this from slowtwitch's venge vias rollout story... when the writer asked why Specialized settled on 64mm for the CLX64 rather than 65mm: "The lead developer responded with a matter-of-fact, 'Because the 64mms tested faster than the 65mms.'" 

So that seems pretty clear, Specialized says that 64mm wheels are always faster than 65mm. It MUST be true.
;-)


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## MMsRepBike (Apr 1, 2014)

Here's an independent test done recently with the CLX64s included.

They pretty much failed. Very flexy, poor profile that's hard on the user, and poor performance both on the road and in the tunnel.



> An updated version is on the way from Roval, and frankly it can't come soon enough.


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## thumper8888 (Apr 7, 2009)

Thanks, that's really interesting. Kind of wishing it wasn't tri-centric, with so many ultra-deep wheels, but it's hard to argue with anything except maybe the tunnel results. It sounds like they MIGHT have used a tire that screws up the Roval's aerodynamic profile. It only takes a small issue with tire shape to pretty much destroy the flow attachment to the wheel, especially off-axis like this.
I realize they were using the same tire for everything except one, but that doesn't mean the tire shape would have been the same... he actually says the wheel pushed the tire width out to what, 29mm?
I can't picture that working. I would only run with with a 23mm gp4000s, which generally tests pretty well in the tunnel, or the s-works turbo 24mm, which is a known quantity with the wheels.
Really interesting test though....


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## Kerry Irons (Feb 25, 2002)

thumper8888 said:


> After all, there's this from slowtwitch's venge vias rollout story... when the writer asked why Specialized settled on 64mm for the CLX64 rather than 65mm: "The lead developer responded with a matter-of-fact, 'Because the 64mms tested faster than the 65mms.'"
> 
> So that seems pretty clear, Specialized says that 64mm wheels are always faster than 65mm. It MUST be true.


Ah, that silly millimeter. It works for cigarettes too, right?


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## thumper8888 (Apr 7, 2009)

I just listened to that video again, more carefully. Something smells... I think they need to take it down.
For starters, the chart for drag appears to be in grams. So... he says the CLX is 14 watts down on the best wheels at 5 degrees and 25 watts down at 12.5
That really, really starts to ring an alarm bell about the data... its hard to imagine a wheel that shape being that far off at 5 degrees. Shapes really get tricky after that, and out to 12 or 15 degrees, yeah, there can be big differences. But 25 doesn't pass the smell test either.
Then, if you stop the video and READ the chart -- if it is in grams -- then the CLX is off 35 grams from the best wheel in the test at 5 degrees and 14 grams at 12.5 degrees.
That should translate to 3.5 watts slower than a much deeper wheel set at 5 degrees and 1.4 watts slower at 12.5 degrees, which is a pretty positive result vs a wheel set thats 6 mm deeper in the front and 16mm deeper in the rear.
If Im right about this, he needs to completely reassess his results.
It's not the order they finished in the wind tunnel that should be important, it's the drag and behavior on the road. And a finish that close to the much more expensive ENVEs is pretty good. Dunno about the handing in gusts, that might be a legit thing, but he needs to go up and down the list and assess that vs the much smaller true differences in watts.

Another alarm bell is that the general curve for these wheels in the test is that they ALL show more drag at 12.5 than at 5, which is not the characteristic you normally see now out of tests of really deep and well-designed shapes like the 808.
Maybe its a function of testing on the bike rather then just testing the wheel, but it goes against what you see in data from Blather about bikes and other places Ive seen.

Also, issue about tire shape isn't a small thing...there is a significant drag difference on the CLX testing thats out there when you switch from just one model of Specialized 24mm tire on the front to another 24mm Speech....
Putting a tire on that wheel that was designated at 25mm -- a mistake already -- and bulbed out to 29mm -- could have cost I dunno 10 watts at 12.5 degrees.
And if you ignore that so much, not just for 
Specialized, but for all the others, which all had different shapes, as to not even mention that it may skew results greatly, you are showing a fundamental misunderstanding of the aerodynamics involved in deep wheels.
Even that V shaped thing that came in last place likely would have benefited noticeably in drag and probably even performance in gusts, by having a tire shape and size that made more sense for it, like a tiny 22mm that would have kept the flow working better at 12.5 and prob even for passing cars.


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## ngl (Jan 22, 2002)

There is such a small speed difference between [many of] these aero wheels that you are not going to feel it, or measure it. So many people get caught up in "which wheel is faster, Brand A or Brand B" when they should also be focusing other areas that can save additional wattage such as tires, gearing, perfecting your position on the bike..... the list goes on and on.


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## thumper8888 (Apr 7, 2009)

ngl said:


> There is such a small speed difference between [many of] these aero wheels that you are not going to feel it, or measure it. So many people get caught up in "which wheel is faster, Brand A or Brand B" when they should also be focusing other areas that can save additional wattage such as tires, gearing, perfecting your position on the bike..... the list goes on and on.



Yeah, that's pretty close to the reason for the original post. Specialized claims differences so great for the CLX64 over others that it WOULD be noticeable.
But often it seems like the tests that feel the most reliable show deep wheels with reasonable shapes pretty close together.
So I wanted to see the data.

And that new bikeradar video we're talking about --- 25 watts of difference between two different but fairly similar designs of deep wheel is almost unimaginable and is in error by a factor of I dunno, ten times?
So, I think the emphasis they're placing on wattage is misplaced, and the bigger, useful differences are braking (esp in wet) and handling in gusty conditions.


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## ngl (Jan 22, 2002)

thumper8888 said:


> Yeah, that's pretty close to the reason for the original post. Specialized claims differences so great for the CLX64 over others that it WOULD be noticeable.
> But often it seems like the tests that feel the most reliable show deep wheels with reasonable shapes pretty close together.
> So I wanted to see the data.
> 
> ...


Yep, Specialized and everybody else does it. You can call it puffing, marketing, lying, or what ever else you want but they all do it because it sells. Buyer beware.


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## TmB123 (Feb 8, 2013)

I know manufacturers need to test somewhere, but I've always been curious as to how wind tunnel results relate to actual real world conditions. I imagine when they say that a wheel is x seconds faster over y distance, that this is in absolute perfect world in ideal conditions, neither of which any of us actually ride in (maybe in a Velodrome, but we are talking road cycling)
I noted when Zipp released the 454's they made a deal of stating that they were tested "in the real world" like it was some sort of revolutionary idea. I was quite bemused about that as thought that would be part of any new release, not just time in the tunnel (I'm sure people do physically ride the wheels, but not sure how much data is collected). How they handle when in a bunch, slip streaming a car, cranked over hard in a corner with wind changing directions etc. They are all things that matter to me a lot more than saving 4 seconds over 40km in perfect conditions.


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