Author Topic: Do any of the Chinese aero/semi aero frames have wind tunnel tests?  (Read 465 times)

Pistonbroke

Got caught up reading about aero and found some data on the amount of watts it takes to push various bikes at along at 45kmh. Wondered if anyone has seen  tests on any Chinese aero frames?
2019 Cannondale SystemSix Disc - 203w
2016 Trek Madone - 204w
2016 Specialized Venge ViAS - 204w
2016 Cervelo S5 - 205w
2016 Felt AR FRD - 205w
2019 Cervelo S5 Disc - 206w
2016 Canyon Aeroad - 208w
2019 Specialized Venge Disc - 208w
2016 Giant Propel Advanced SL - 210w
2016 Scott Foil Premium - 211w
2016 BMC Time Machine - 211w
2016 Look 795 - 212w
2019 Trek Madone Disc - 212w
2019 Ridley Noah Fast Disc - 213w

Obviously tests will depend on a variety of factors and different protocols will yield different results.... It was just a pondering on my part:-)



Serge_K

Re: Do any of the Chinese aero/semi aero frames have wind tunnel tests?
« Reply #1 on: September 26, 2024, 03:42:09 AM »
Please quote source, out of respect for those who did the work, and because it's helpful.
Is it the cycling news study behind the one GBP paywall?

You also need to specify the test protocol: what wheels and tyres is it tested with? The wheels and tyres can easily be responsible for half or more of the variance between bikes - unless they're standardized ofc.

To answer your question, the tavelo arow, I think, markets wind tunnel testing. And the alilee/ delilee/ some name with "eeee" sounding name (as featured on cam Nichols YT channel a few weeks ago).

Have you looked at the German website that tests bikes in the wind tunnel? Forgot the name. It's been discussed multiple times on the Nero show (YT).
Fast on the flat. And nowhere else.

toxin

Re: Do any of the Chinese aero/semi aero frames have wind tunnel tests?
« Reply #2 on: September 26, 2024, 05:44:18 AM »
He posted tour magazin data, though really old sets. Arow wasn't tunnel tested. Seka spear, incolor intropy, xds ad9 were, though the xds setup was very dodgy.

Pistonbroke

Re: Do any of the Chinese aero/semi aero frames have wind tunnel tests?
« Reply #3 on: September 26, 2024, 07:38:07 AM »
Sorry guys, results came from weight weenies discussion on tour magazine results.
https://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=154692

It's more a question of curiosity and a slight hankering to build a light aero ish bike to see if it makes a difference... Although I don't think a 10watt difference is going to change my cycling career now lol.

toxin

Re: Do any of the Chinese aero/semi aero frames have wind tunnel tests?
« Reply #4 on: September 26, 2024, 07:59:48 AM »
Those numbeds are also weighted. They take drag numbers at different yaws and use an equation to get a number from those measurments. The equation favours lower yaw angles, but it still dpesn't tell the whole story. For example: S5 and Aeroad have the same result in tour tests, but if you look at tests that show the yaw/drag graph, you'll see that the S5 if faster at lower yaw angles (no wind of full headwind) and the aeroad if faster at higher yaw angles (crosswinds). Even though the equation tries to balance that out, the reality is that in real world conditions the S5 should be faster something like 90% of the time.

Tour did show these graphs once upon a time but they havent been done it for a while now.

patliean1

Re: Do any of the Chinese aero/semi aero frames have wind tunnel tests?
« Reply #5 on: September 26, 2024, 08:25:36 AM »
Having seen some of those mobile wind tunnel testing machines on wheels which some of the Chinese brands use, I would not put much credence in their data. I'm not saying those mobile units can't be effective. But I suspect brands use it mostly as a marketing tool.

I could be wrong...

toxin

Re: Do any of the Chinese aero/semi aero frames have wind tunnel tests?
« Reply #6 on: September 26, 2024, 08:27:18 AM »
All the ones I listed were in proper wind tunnels, not like the joke that is winspace
« Last Edit: September 26, 2024, 08:36:13 AM by toxin »

Serge_K

Re: Do any of the Chinese aero/semi aero frames have wind tunnel tests?
« Reply #7 on: September 26, 2024, 09:28:30 AM »
I (very) recently heard on some video or podcast that wind tunnel employees say (that may not be the official stance of the tunnel) that from one session to the other, you can't really compare results. I'm sure if you're testing a box rim vs a 80mm one, the results will be consistent, but to test 202W vs 204W, it's a fraction of 1%, and the definition / repeatability of the setup just isnt there between sessions.
And that, btw, presumably, implies that if you happen to use different tunnels in your testing over time, then you really ought to question your data.

I wonder if this is something tour magazine has addressed, as i suspect they do multiple short sessions in the tunnel(s?) over years, and not batches.
Fast on the flat. And nowhere else.

precision6625

Re: Do any of the Chinese aero/semi aero frames have wind tunnel tests?
« Reply #8 on: September 26, 2024, 11:07:27 AM »
The Tour Magazin tests are by far the best out there (way ahead of anything from GCN, Cycling Weekly, Bikeradar, Bikerumor, etc). They test at the GST wind tunnel, this is the same wind tunnel Swiss Side uses. They use a moving leg dummy.

But indeed, you can't take take the results at face value. The main problem is that they don't standardize the handlebar, which is a big part of the aero equation. The wheels can also be a problem -- sometimes they give an additional figure with the reference wheelset (Zipp 404), but sometimes they don't.

For example, they're tested the 3T Strada (both the 1st and 2nd gen), and they give it 211w and 210w respectively with Zipp 404s. But then you realize that both were equipped with round-ish fully-wrapped bars...that's another ~7w, which makes the 3T Strada just as fast as the fastest mainstream bikes (Aeroad, S5, SystemSix). Yet the Strada is never referred to as such.

I believe the only open mold frameset they've tested is the Baldiso Air Flight One, which is the Workswell WCB-R-306. It scored 212w with 50mm wheels and a one-piece aero handlebar, so it's a fair bit slower (~8w) than the mainstream aero bikes. There's also the Myvelo Verona, which I assume is some open mold frameset (not sure), and it had a terrible score around 222w with Zipp 404s and a one-piece aero handlebar.

Those numbeds are also weighted. They take drag numbers at different yaws and use an equation to get a number from those measurments. The equation favours lower yaw angles, but it still dpesn't tell the whole story. For example: S5 and Aeroad have the same result in tour tests, but if you look at tests that show the yaw/drag graph, you'll see that the S5 if faster at lower yaw angles (no wind of full headwind) and the aeroad if faster at higher yaw angles (crosswinds). Even though the equation tries to balance that out, the reality is that in real world conditions the S5 should be faster something like 90% of the time.

Not sure I follow your reasoning. The weighting function is based on real-world yaw distribution, so if one bike has a lower weighted drag than another, it will be faster most of the time in the real world. If one bike is 5w faster at 0 yaw than another bike that is only 5w faster at 10deg+ yaw, then this will surely be reflected by the former having a lower weighted drag.

toxin

Re: Do any of the Chinese aero/semi aero frames have wind tunnel tests?
« Reply #9 on: September 26, 2024, 06:32:54 PM »
Not neccessarily, if one bike is really good at low yaw angles and bad at high angles, and the other is a little worse at low yaw and much much better at high yaw angles, they can still get a similar result