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rustychain
PostPosted: Thu Mar 03, 2011 10:25 pm 
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Kudos for the frame review. Understanding the limitations that frames handle differently for riders of greater or less weight then the range they were designed for and wildly differing opinions on what a good frame is.
Carbon wheel review..... Not so much. Important issues were left out IMO and trivial issue ( hub noise for example) received to much weight. Having owned or tried all the wheels tested I'm at a loss to understand VN's conclusions. Maybe it's just me?

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funhog1
PostPosted: Thu Mar 03, 2011 10:53 pm 
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I'm wondering......

VNTech........

as it's too daunting of a task for my schedule......

if you guys would be interested in having a clever VN intern collect/collate data for some regression analysis? :D

Maybe start with actual real world road race results to attempt to figure out the measurable benefit (if any) of riding an aero frame in a road race? Just for fun?

Thoughts?

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Last edited by funhog1 on Thu Mar 03, 2011 11:11 pm, edited 1 time in total.

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djconnel
PostPosted: Thu Mar 03, 2011 11:11 pm 
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Problem is if the fit isn't absolutely dialed in each case, body position differences can dominate.

It would be like trying to measure the benefit of 100 grams saved: you'll never see it in real world data.

But I like your idea!

P.S. My big issue with their aero wheel tests was they had two parameters devoted to weight: rotational inertia and actual weight, and one devoted to aerodynamics, and each was rated with equal weight. Since translational inertia is always a larger impediment to acceleration than rotational inertia (except on a trainer) and since it also applies to climbing power, obviously total weight is much more important than rotational inertia, and for aero wheels both are much less important than aerodynamics.

This frame test, with the exception of the lack of water bottle, was much better.

funhog1 wrote:
I'm wondering......

VNTech........

as it's too daunting of a task for my schedule...... :mrgreen:

if you guys would be interested in having a clever VN intern collect/collate data for some regression analysis? :D

saaaaay actual real world road race results to attempt to figure out the measurable benefit (if any) of riding an aero frame in a road race? :shock:

Thoughts?

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funhog1
PostPosted: Thu Mar 03, 2011 11:22 pm 
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Indeed.

True.

I agree with your points, and

I think some analysis may be achievable. For example use RA in an attempt to look for correlations between the average speed of the peloton increasing over time and technology changes within the industry and then within that frame start to look for any benefit to riding an aero bike in a road race.

If VNTech has the time maybe something would turn up.

Just for fun?

Accounting for changes in road surfaces and tire technology alone would be quite the thing......

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djconnel
PostPosted: Thu Mar 03, 2011 11:49 pm 
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Bicycle Quarterly did a similar analysis to look at the effect of the derailleur on European race speeds. Even with as drastic a change as that, the "signal" was hard to see above the "noise". In particular there's always other things changing, like anti-doping enforcement.

Here's trends in 10 km running, from Science in Sport:

Image

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tanhalt
PostPosted: Fri Mar 04, 2011 12:14 am 
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djconnel wrote:
The low-yaw CdA, bike no rider, Zipp 404 wheels... I assume air density = 1.185 kg/m² at the North Carolina wind tunnel.


"standard bike" (unspecified): 0.106
Felt AR: 0.092
Ridley Noah: 0.087
Blue: 0.085
Cervelo S3: 0.083

The contrast with the Tour results really couldn't be more striking. There, the Cervelo was actually slower than the Cannondale System 6 at zero yaw.

Tour reported a typical CdA for zero yaw with rider is 0.31. So a difference of 0.023 (the Cervelo to the "standard bike") is around 7.4% of total wind power. At 40 kph the power difference is 18.6 watts out of 250 watts. At this speed, 33 watts is a typical rolling resistance power (12% of total). Thus, a 7.4% reduction in wind resistance power is around a 2.3% savings in total speed: 85 seconds / hour.

VeloNews claimed more than that: 128 seconds. But they average over yaw angles from -20 to +20 degrees.

I think omitting the rider should overestimate the aero benefit somewhat, so I'd view the VeloNews results as an upper bound on possible savings.


Perhaps the above reflects the results of actually including cables and housing in the testing? The cable runs are MUCH less exposed on those aero bikes than any "standard bike"
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djconnel
PostPosted: Fri Mar 04, 2011 12:30 am 
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Good call. Also the rider's legs tend to nullify the advantage of an aero seatpost, which gets clean air in the VeloNews test (and has nothing trailing it, so if air can get by the seatpost intact, it's clear).

A waterbottle would have neutralized a nice section of the downtube, but both tests make that mistake.

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6ix
PostPosted: Fri Mar 04, 2011 12:56 am 
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prendrefeu wrote:
Good to see that the Blue is just barely "slower" (??) than the Cervelo.

In other words: save yo'money! :mrgreen:


When we designed the AC1 SL, we had far less R&D funding too. Just goes to show that having experience in the saddle and in design is paramount. Just wait until you guys see the next version!!
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prendrefeu
PostPosted: Fri Mar 04, 2011 1:15 am 
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6ix - are you from Blue?

Talk to a moderator, they'll set you up with a manufacturer's account.

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VNTech
PostPosted: Fri Mar 04, 2011 11:07 pm 
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I've been told by our IT people that you should be able to view 15 pages of the current issue without subscribing using this link, which should take you to the first page of the tech section: http://www.velonews-digital.com/velonew ... &u1=friend

Chose your 15 pages wisely! Someone let me know if it doesn't work.

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spartan
PostPosted: Sat Mar 05, 2011 2:11 am 
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thx vntech but cervelo has posted the entire article on their site

http://www.cervelo.com/reviews/Velo_News_2011-04.pdf



btw everyone should look at this article. if you disregard the cervelop4 great numbers at 0-5 yaw(they using uci-illegal ventus bar) all the super tt bike are very close. notice the difference a round water bottle makes to the drag numbers.

when will velonews do a aero test on tt frames ?


http://www.slowtwitch.com/Tech/P4_in_th ... _1929.html

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funhog1
PostPosted: Sat Mar 05, 2011 4:18 am 
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Good test. Thanks for making it fun and not taking it too seriously. I loved Ben D's response to Caley's experience with the Noah. At 132lbs I looooove system six's.

AND I love the ambient noise you provided about *fit* (and user/wrench friendliness) The Rotor Cranks = doo, and yes the lack of zero setback options.... equally awful as well.

a Gi-normous thumbs up :thumbup: and grazie for the link

VNTech wrote:
I've been told by our IT people that you should be able to view 15 pages of the current issue without subscribing using this link, which should take you to the first page of the tech section: http://www.velonews-digital.com/velonew ... &u1=friend

Chose your 15 pages wisely! Someone let me know if it doesn't work.


However....

"Whether you're racing or just want to beat up on your buddies, an aero road bike can provide real gains over your current round tube bike". VNTech

As that is stretching it...... it would have been more accurate to say *may* instead of can. May provide a benefit depending on a potentially transfinite series of road race metrics.

Also... where was the difference in aero performance on the standard bike with 404 wheels?

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tanhalt
PostPosted: Sat Mar 05, 2011 7:39 pm 
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VNTech wrote:
I've been told by our IT people that you should be able to view 15 pages of the current issue without subscribing using this link, which should take you to the first page of the tech section: http://www.velonews-digital.com/velonew ... &u1=friend

Chose your 15 pages wisely! Someone let me know if it doesn't work.


Any chance we can find out what bike and wheels were used as the "standard"? That would REALLY help put things in perspective.
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BeeSeeBee
PostPosted: Sat Mar 05, 2011 9:35 pm 
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spartan wrote:
btw everyone should look at this article. if you disregard the cervelop4 great numbers at 0-5 yaw(they using uci-illegal ventus bar) all the super tt bike are very close. notice the difference a round water bottle makes to the drag numbers.

when will velonews do a aero test on tt frames ?


http://www.slowtwitch.com/Tech/P4_in_th ... _1929.html



Well for what it's worth, the Trek's bars are also UCI illegal (though not 22:1 aspect ratio illegal). And the Giant and Specialized both have their UCI illegal nosecones attached. Of course the test was for triathletes who buy 95% of those bikes, and don't care about UCI legality.

If a company is going to make an integrated front end with their own proprietary bars like Trek, Giant, and Specialized, or semi-integrated with it's own proprietary stem that accepts bars without an integrated stem like the Scott (note: they even used the USE Tula for the Scott, which is supposed to be an incredibly fast bar as well) then I think it's a fair test. The moduability of the P4 is one thing it has going for it, you can use all of the most aero equipment without resorting to jury rigged setups, and questionable integration issues.

They're all very close, and once you get the rider on there, the differences are so minute.
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djconnel
PostPosted: Mon Mar 07, 2011 2:11 am 
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Interesting aspect of this test: how much better the Felt did with the Zipp 440 than it had done with the "stock" Mavic Cosmics.

Another interesting point: it is mentioned the Felt may have suffered at zero yaw due to its heavily padded handlebar tape and fat handlebars. And I'd thought Oval Concepts claim that 26 mm bars had superior aerodynamics was excessive. It was surprising to me the Felt did worse than the Ridley at zero yaw, despite a slimmer head tube.

And then the apparent importance of internal cables. I like the point which was made here that this may help explain why the Cervelo did so much better at zero yaw here relative to the "control" bike than it had with the Tour test: in the Tour test there were no cables to hide.

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