Food for thought - aero (Watts) content

I came across this article from Bike Rumor the other night; sorry CT for cross-posting from another cycling website :slight_smile:

I found the numbers quoted by the Swiss Side CEO to be quite interesting, and decided to crunch them a bit for a hypothetical “aero-optimized” scenario at speeds us mere mortals can ride at (power is proportional to velocity cubed so the math is easy to do). I chose 30 kph / 18.75 mph.

Base setup: upright on the hoods, loose fitting clothing, standard shallow wheels, non-aero helmet and non-aero frame
Aero setup: bent arms on the hoods, skinsuit, aero wheels, aero helmet and aero frame

The difference between these two hypothetical scenarios is about 54 W, which is huge of course. The breakdown of the individual components looks like this:

Position on the bike = 25 W
Clothing = 9 W
Wheels = 4 W
Helmet = 3 W
Frame = 13 W

This is probably a good “upper bound” and real-life savings are much less. Maybe our friends at CT can do a field test (in a velodrome, perhaps) and put some of these to test?

On a somewhat related note, I rode an Emonda SLR7 this morning with aero wheels, and felt like I was flying compared to my Argon 18 Dark Matter which I ride on the road with 40c slicks :smiley:

Edit: I updated the power saved after finding a mistake in my initial calculation, and also included a breakdown of the individual components.


Interesting article, and even more so the fight over alu/carbon numbers in the comments

And the winner is…
Lycra shoe covers.
(So an old article I read once said.)
They are cheap and give you areo gains. (Bang for buck)
But then that is subject to your body position. If you don’t need lessons for yoga then that is cheaper again for huge gains.

Alex Dowsett said for his hour record attempt that lifting his head cost him 20W and his coach would constantly remind him to keep it down because of the massive impact to aero.

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I believe shaving your legs is the best w/£ gain you can make.

Edit: skimmed the article.

Key takeaway: ride in as aero a position as you can comfortably hold (for which, invest in a bike fit and do some off the bike work), wear tight-fitting clothing, and shave your legs, and you have probably got close to 90% of the aero advantage you could ever get (on a road bike), for very limited outlay.


Never mentioned innertubes. I have heard many times a latex tube will save a lot more in price than any other upgrade bang for buck wise anyway.

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The article did not mention latex tubes because it was about aerodynamic improvements :slight_smile:

Latex tubes can make a sizeable difference of course, and are also not speed dependent. Even better if you can put those latex tubes inside tires with low rolling resistance!


Position, as other said, is the most important, and free, aero gain one can get.
I’m working on my position on the bike and I must admit that the improvements are surprising.
There’s a Strava segment I created that represents a 10 mile TT over rolling terrain, 20 minutes from my door. My best time dated back to 2019 but a couple weeks ago I got quite near it again.

Well, today I rode it again keeping a more aero position (hands over the hoods, forearms parallel to the ground etc).

In spite of a heavier bike and a slightly lesser speed in descends (because wet fallen leaves), I did my PB in three years. 13 seconds less than my 2019 best, and 41 less than my 2021 best.

I’m keen to try clip-on aerobars now.

Congrats on the PR……Are you tracking your power and weather conditions during these runs?

That’s what should be undoubtedly done to be scientific.
No, I’ve got no power measurements save for what strava calculated (read: guess).
Yes, weather is taken into consideration, especially the wind of course.

Yeah, you can’t rely on the crap numbers Strava “calculates”.

It is great that you are getting faster, because that is the name of the game, but you just don’t know if it was because of your position, improved fitness or both.

Yes there may be even more than those factors involved. Could be tires pressure.
But it’s unlikely my level of power increased a lot in one week. Wind was, well it was crosswind in the part of the course were wind plays a substantial role. My time gains came from that hill and from the following twisty descent. The rest of the course didn’t deviate so much compared to my previous best.

Nevertheless I find interesting that my PB in two years came exactly when I pushed my position to a decent aero conscious one, in spite of a heavier bike.We are looking at a sample total of 24 rides.

On a side note: I don’t rely on Strava estimated power, primarily because I have scarce interest in training things, but:
I remember that someone made a comparison (somewhere in the internet it’s published) between Strava’s numbers and its power meter numbers and, surprisingly to me, they weren’t as far apart as I expected them to be.