Dubious aero claims

On NorCal cycling I saw an oldish post where they’d tested a Venue with a non aero bike with aero wheels and un surprisingly the aero bike was 12 seconds faster if I remember correctly over about 12km I think it was. Seemed about right, then I saw they’d used Vittoria Rubino tyres on the non aero bike and Specialized cotton tyres on the Venge. When you consider rolling resistance… This is taken from Bicycle Rolling resistance:

Rolling Resistance Test Results
Model Turbo Cotton 24 Rubino Pro Control 25
Spin Up Video YouTube YouTube
Inner Tube Conti Race28 (100gr butyl) Conti Race28 (100gr butyl)
Measured Width
Rolling Resistance

Ultra High Air Pressure 10.1 Watts. *****SPECIALIZED TURBO COTTON
CRR: 0.00303
(120 psi / 8.3 bar) 16.9 Watts. *****RUBINO PRO

This is a per tyre value, the Rubino is almost 7 watts per tyre (!!!) slower. That means 14 watts slower for both tyres. I am almost certain that that would more than make up for the small difference in speed on the 2 bikes. What you have effectively just done is prove that the Venue is no faster than a normal non aero bike. (Disclaimer, I own a fairly aero road bike so I have zero skin in the game for de bunking aero stuff).
I think there’s a LOT of BS about aero. I can’t help coming back to Allaphilipe’s round bars. Allegedly that’s worth 7 watts at 40k an hour. I get that he prefers them to aero but if the 7 watts is real there is no way a pro would give up 7 watts of free power. That’s a huge amount of watts when you’re dealing with the top end of the sport…

They certainly could have controlled their on road experiment better. That said, 17W at 120 psi isn’t necessarily 17W at whatever pressure they actually rode at (not 120, I’d assume, that seems high for a 25c tire.

12 seconds over 12k seems like a lot for an aero road frame. Over 40k it seems plausible.

If you think a pro rider would never give up free watts over whatever equipment preferences they have, you’re sorely mistaken. And you don’t listen to the Marginal Gains Podcast :sweat_smile:

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Ok, on a slightly different note on aero gains, have you noticed that the difference between crushing your local group ride and really sucking is about 20 watts on your ftp. Try getting the latest aero whatever that allegedly saves 15 or 20 watts, or shaving your legs which according to specialized is about 20 watts and it doesn’t seen to make any difference at all.


I don’t think you can make a 1:1 comparison on power deltas in group efforts vs pure aero testing data. Unless you are talking about solo TT type efforts, the dynamics of group efforts with variable power and efforts will necessarily be erased by even the most clear aero gain.

It should help, but without looking at your placing in groups, how & when you apply power and such, I think you want to consider aero in groups with a more cautious approach.


I have a standard circuit I test things on and yes there’s a difference between tops and hoods but after that, nothing seems to make any difference, hairy legs seem to make no difference either even though Specialized say it’s worth 20 watts. But you know what does make a difference? Riding 20 watts harder. That tells me that there isn’t a problem with my testing protocol but rather a lot of the aero stuff isn’t real.


It was a long time ago, but I studied aerodynamics in college. A lot of the claims are plausible, but frankly I believe many are overstated for marketing purposes. When you look at some third party tests though, Specialized’s gear breaks out pretty well relative to some others.

That said, I think lab environments are likely poor predictors of real world performance, but it’s what we have. I personally do not chase claimed aero watts that cost additional money, but to each their own!

(Disclaimer: until recently I rode a Venge, I love my CL50s and have no plans to “upgrade” on my new frame.)

Roval CL50 vs Enve and others

The single biggest determinant of aerodynamics is rider position, and a lot of that is related to comfort and sustainability of that position IMHO.


The thing with aero gains is that they’re usually measured in Watt savings to go the same speed, and usually measured in a vaccuum with an otherwise non-aero setup. E.g. the rough bar savings is if you have a standrad road bike with box section rims- its published that way to get the biggest aero savings. Combining aero gains isn’t straight additive due to diminishing returns.

From a practical standpoint too, the faster you go, the higher the aero drag, and more watt savings doesn’t translate into faster speed. Aero definitely isn’t bs- I did just under 27mph on rolling terrain (400ft+/10miles) on 280WNP. But drag increases exponentially, so saving 10W at 27mph probably only nets you something like 0.1mph, whereas it would net you 0.5mph at 20mph (not exact numbers, just as an example). The savings become much less noticeable from an results standpoint the faster you go.

The whole savings in terms of watts is what is so misleading. It needs context, and obviously has it under the hood, but is misleadingly advertised otherwise. For example, the savings in watts should be expressed as a function of speed. Ex: savings of 10 watts at 30mph. So if it took you 400w to go 30mph without the new equipment, it’ll only take you 390w to go 30mph with the equipment.
This is misinterpreted and used in marketing to suggest that, for example, your ftp will be 10 watts higher, or something to that effect. When in reality, since these relationships aren’t linear, saving 10 watts at 30mph may allow you to put out the same 400w (rather than 390w to produce 30mph) and instead go 30.05mph! When it’s truthfully expressed like that, you don’t feel like spending $400 on the ‘marginal gain’.
Theses aren’t real numbers, but they get the point across. So, yeah, pros don’t really care bc it won’t win them the race. They just ride what the sponsors pay them to wear




Interesting, we all know how hard it is to gain 10 watts of FTP and the difference when you do is definitely noticeable. So you’re saying 10 watts saved is different to 10 watts gained? I’ve never heard it put like that. With regard to pro’s riding what they are paid to, Allaphilipe’s team ride Shimano’s Pro range of stems and bars so he could easily go with the Remco style super aero one piece type thing. With my initial example from that NorCal test, the difference between total aero and aero road bars and total non aero frame and bars made only 12 seconds over 12km and then I noticed the non aero had one of the slowest tyres and aero had the fastest tyres which are 12 watts faster… Something seems off. (disclaimer, I currently ride an aero frame and 50mm wheels and usually a pretty aero top at least)

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I think their issue is that the marketing makes it sound like it will be 10 watts easier to do 30 mph. When in fact it needs to be qualified such as it will be 10 watts easier if you are out front in the wind but if you are in the bunch then there is no advantage. Whereas when you gain 10 watts in ftp that is always with you whether in the wind or in the draft thus why you notice it so much more.


That’s a good point. 10 watts on your ftp is 10 watts all the time. Same with rolling resistance.

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So personally I stopped training after reading the article below.

  • 44W on tires and tubes
  • 35W on clothing
  • 18W on drive train
  • 14W on handlebars

111W total will get me through the summer season :smile:

(And yes, I know Silca is a fine company)


I mean you have to actually read the article to see what the baseline comparison is. For tires they are comparing corsa speeds to gator skins and assuming your running at high pressure and using butyl tubes. So yes absolute worst to best setup 44w is a achievable increase, for most it’s going to be far less.

Similar with the rest of their recommendations, yeah if you go from a loose flappy club fit jersey to full tt skinsuit, aero socks and helmet your going to save a lot of watts.

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omg! I’ll be a 1st cat next week when I get all this new stuff! Can’t wait to line up on that start line!


Rolling resistance is proportional to speed as well. It’s linear instead of exponential so it’s not as dramatic.

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Same here. Ordered all this stuff and told my friends I am joining a faster group ride going forward


If the companies pushing half this junk had to confirm their claims with independently verified testing… they’d have nothing to sell you.

The cycling industry.

“Dude, just say, it’s lighter and stiffer, they’ll buy it.”
“No way, it can’t be that easy.”
“Seriously, that’s all we have to say.”
“What about aero?”
“Same, just say some watts saved stuff.”
“They won’t test it, there’s no regulation?”
“We’re going to be rich.”


My 2c as someone who does aero development on cycling products but also goes on group rides and knows what you are talking about when it comes to what really feels like it makes it ‘easier’ :smile:

  • I think it’s a reflection of the relative infancy of aero technology within the cycling consumer industry that, fortunately, people are becoming more discerning and real, credible gains are really important. On the whole, Pro teams who often drive a lot of the kit development are a lot more clued up in this respect now than even just 5 years ago.
  • The physics of winning bike races or going well in a group ride is about far more than just aero. The bandwidth of aero influence in those situations can easily be swamped by talent, tactics, fitness, mass differences.
  • I’ve heard things like the Alaphilippe bars scenario so many times - ‘how bad can they be’? See point above. They would have been slightly faster if they’d have had the more aero version. But maybe when you are doing it for a living and moreover, have ~20 years of experience of being successful with certain types of kit that you are comfortable with, thats a pretty big thing to shift. Most of the younger generation take all the kit upgrades they can get.
  • It’s fair to say also that reliability and handling are just as important in pro racing as aero and mass. It seems we are slowly getting products in the marketplace where you don’t have to compromise on one or more of these if you’re willing to pay for it. As noted there are some things that maybe even current pro teams are sponsored to use that don’t tick all the necessary boxes.
  • There’s been a few features I’ve seen recently illustrating how much trickle down there has been to entry level road bikes and how good they are. I think that’s a good illustration of the above.
  • Its fair to say that unfortunately, a lot of these things are for most of us zero sum gains - whether consciously or not, everyone we are riding/racing with is generally buying new stuff that will be a bit faster than their old stuff.
  • Power and mass are important. So is aero. You don’t need to be, and shouldn’t, be polarised about it.
  • If you’ve only got capacity to think about one, that’s fine, but it’s even better to improve on all fronts.