5-6%

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BIKE DESIGN AND +

http://cds-0.blogspot.com/

Do you all believe aero wheels provide an advantage, despite the fact that the data that prove their advantage comes from testing performed without all these other variables you think somehow remove aerodynamic advantage?

In fact, wheels are generally tested even more poorly, as they are rarely tested IN a frame and fork, making the tests absolutely nothing like the real world. And yet, the advantage of aero wheels is rarely argued against.

We tested aero wheels in a bike, and saw excellent gains. We tested aero road frames, and saw smaller but still excellent gains. Somebody please explain to me why these two results are being treated differently.

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VeloNews Magazine/VeloNews.com tech
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That seems like a very worthwhile advantage to have in any race situation.

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2010 Guerciotti Whisper
2007 Bianchi 928L (update Sep '11)
1999 Bianchi MegaPro 25CrMo4

If I'm pulling out a big 5 min effort to break away, I know from my power curve that an extra 5-6% takes my power from what I would produce over 5 min to closer to my 3:30 power.

That is certainly something I would not sneeze at.

I think VNTech makes some good points. But thisisatest else nailed it when he said



or, even more simply

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Baum Ristretto, Baum Mondrian Corretto & the '89 Merckx! | "If you could eat it in one sitting, hold your line." | twitter.com/Tinea_Pedis

I sure know that I wouldn't bet when it comes to that.

A helmet and a face will change the total amount of drag, but I just don't see how it would affect the airflow around the frame, so I'd have to think it only shifts the y-axis.

Bottles and cages could very well work in favor of an aero frame. Maybe the difference between a round tube frame and say the S5 or Neil Pryde is larger once you put the bottles on, because the air is led around them entirely? Not saying that happens, but it could be.

Same goes for cables and housing. Maybe cleanly routed internally the difference grows?

Shifters and bartape might have an effect on the airflow around the HT, especially at higher yaw, but I doubt they'd negate any aero benefit.

I guess it all depends on what side one puts the burden of proof. If you want hard data that a bike with airfoil shaped tubes is faster than one with round tubes in the real world you're always going to find something. If you think that bar tape on or off makes a test useless or just a tad less precise is up to you.
If you accept that an "aero" frame has less drag than a "non-aero" frame I believe you can see a trend in the data which might even be helpful.

What I like is that there really isn't a clear "aero" or "not-aero" distinction any longer. Cervélo had the R3 and the Soloist, where the R3 is the comfy long distance bike and the Soloist is the cheat the wind bike. Right now I ride a Parlee Z5 and race an aluminium Soloist, which is the best of both worlds, IME, but my races are usually short crits with rather smooth roads and not everybody wants two bikes.

Now with the Neil Pryde, for example, it's pretty much right in the middle. I was very surprised how nicely that rode for a bike I had in my mental "aero" drawer. It's definetly not a bone shaker, corners really well, is responsive and could easily built up to 6.8 even with deep wheels. I suppose they made the bike they wanted and then made it as aero as they could given what they had instead of making a bike super aero and then try to figure out how to make it feel like a nice ride.

At that point it really becomes a win-win, not an either this or that.

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"Nothing compares to the simple pleasures of a bike ride," said John F. Kennedy, a man who had the pleasure of Marilyn Monroe.

Right to counter, the wind tunnel tests in Top Velo showed Zipp 404's to be worth all of 0.5 sec per KM, an aero frame less. Now given that tunnel results do not seemingly translate into the real world and overstate the benefits by apparently 50%, the real benefit at 40kph of a frame is likely to be circa 0.3 secs per km.

Standing up to avoid a bump will cost me at least three times that - coasting over rough ground likewise.

The argument is that the benefit is remarkably small and may not even exist in the real world. There is no evidence to date that this argument is misguided.

I'm not looking to convince you, please refer to my last 2 sentences.

As with anything that's had a decent amount of tests/research done on it, you can find tests that disprove the findings of another.


For mine, if choosing an aero frame certainly isn't going to hinder me then I would see no reason not to grab one with both hands if the option was available to me (sadly, it's not).

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Baum Ristretto, Baum Mondrian Corretto & the '89 Merckx! | "If you could eat it in one sitting, hold your line." | twitter.com/Tinea_Pedis

I agree that aero frames do have some benefit. But, if I'm slow on my as-aero-as-a-brick BMC, then I'm probably going to be just as slow on a Cervelo S5.

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Slam your stem.

I'll again quote him, as he hit a lot of nails on the head

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Baum Ristretto, Baum Mondrian Corretto & the '89 Merckx! | "If you could eat it in one sitting, hold your line." | twitter.com/Tinea_Pedis

Anyone in Melbourne know of a shop who would give me an aero bike to use on a 40km ride?

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Slam your stem.

If those numbers are correct (which i don't know), then i don't see how you can say the benefit is small: 0.3 sec per km in a 200 km race is a whole minute...

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2010 Guerciotti Whisper
2007 Bianchi 928L (update Sep '11)
1999 Bianchi MegaPro 25CrMo4

Honestly, I believe that aero frames do have their benefits. But I think it depends on what kind of rider you are. If you're typically on the front of the pack attacking, or sprinting, yeah, that aero frame might squeeze out some watts here and there. But if you're a climber or someone who's just sitting in for whatever reason, you'll probably feel the benefits of a light frame much more than you will an aero one.

For me, a lighter bike/wheels is much more noticeable. I weigh 120lbs and climbing is what I really excel at--is having an aero frame on an 8% grade really going to help me all that much? Probably not. But I can tell you that I can definitely feel the lighter weight of my R3 underneath me more than anything else. Of course, if you're a 170lb rider and you're off on some solo attack, your results will be different. If you're weighing the options, you should probably understand what you're going to be doing with the bike first.

Agreed,

but I'm the 160 lb rider who can't climb or solo attack =]

the point is there usually will be something to hinder you. Lack of comfort. Lack of stiffness resulting in compromised handling. Extra weight. There was a time when a bike needed to be stiff light and comfortable. Aero seems to demand compromises in all of these.

airwise,



By the figures above, aero wheels are worth something like Cd=0.05, frame about Cd=0.03. These are relatively big numbers! To put this in context, assume two riders hit the front of the bunch at 40pkh. Rider A has a Cd=0.8, rider B has Cd=0.79 (a 1-point change, i.e. much smaller than the above numbers). Both start to put out 800W and hold it. The difference between rider A and rider B is something like 10cm after 100m. The difference grows over the next 100m because aero power goes with v^3. That 10cms is clearly a race-winning difference, all else being equal. The faster you go, the bigger the margin; the further you go, the bigger the margin. I'd take that advantage, thank you very much!



Sorry, this argument - sensitivity to the real world not only swamps any aero gains, but swamps them differentially with better aero worst affected, such that the playing field ends up level - is very wrong, and is not seen in other areas of engineering where high aero performance is required. E.g. motorsport. Have you seen pictures of F1 cars after a race? Tyres shredded, bits of CF missing, dead bugs over the aero surfaces, not to mention manufacturing "features". Of course, sensitivity to real world effects is super important (actually one of the most important areas, tbh!), but to argue that because real world effects exist, any attempt at aero performance gains is not worthwhile, is misguided.