Aero, or Die. Right?
Aero, or Die. Right?
I've worked with athletes across the spectrum - World Tour to people just wanting to ride 100 miles as easily as possible. And, across a variety of disciplines ultra endurance racing to track sprint. And, the thing that everyone wants (whether they realise it or not) is more speed. Everyone wants to be faster. There's no doubt: training makes you faster, as does nutrition, but there's a third option that some people simply don't bother about: aerodynamics.
Back to the cohort of people i've coached -- one thing that is a common misconception is that some, 'slower' riders think that aero isn't for them. "I'm not fast enough". So, they don't bother. However, the inverse is true: the slower you are, the larger the time reductions are for improved aerodynamics. So, over the last few weeks, I set out to validate what "aero" is worth.
Your aero drag is measured by a metric known as CdA (coefficient of aero drag) and measure in m² (metres squared). An average road position is around 0.35 - 0.4 m², while a fast aero road position would be about 0.26 m². TT riders are going to be around 0.2 m² or under (at least if they have an excellent position).
Local to me is an outdoor velodrome. It's about 570 metres long per lap. I decided, with some willing subjects, me and two coached riders (both the same height but different masses) went down the track and measured the differences that clothing makes to your speed. I'm confident that we were just measuring clothing (other than body position and size) because, in a bizarre twist of fate, we all had the same bike and equipment (other than size and paint differences!).
First Test: Kit Comparison
Rider A (49 kg, 164 cm) and Rider B (65 kg, 176 cm) did moderately hard multiple laps on the velodrome. Rider A was wearing a race jersey, race gilet and shorts. Rider B was wearing Roubaix longs, Roubaix jacket and a loose gilet.
Rider A required 147 W to ride at 32.6 km/hr. This back calculates to a CdA of 0.245 m². Rider B required 220 W for 33.1 km/hr, which back calculates to a CdA of 0.38 m².
Please note that all these CdA back calculations are being used relatively. It's likely that environmental conditions (which weren't being measured - just estimated) would affect the absolute CdA. However, as tests took place at the same time I can only presume that each rider had the same environmental conditions -- so absolute CdA is unimportant here - we're just looking at the relative effects. And, again, the CdA will differ on different days -- so it's harder to be confident that absolute differences are "real".
Then Rider B rode sans gilet. This took their power down to 172 W for the same speed and reduced their CdA to 0.299 m². A massive improvement.
Rider B's loose gilet cost approximately 48 watts for the same speed. That's the single largest penalty we measured.
Data from me suggested that my CdA while wearing bib shorts and a Roubaix jacket gave me a CdA of 0.277 m², which was very close to my actual measured CdA (I've been aero tested in a wind tunnel).
Second Test: Skinsuit vs Jacket
On a separate day, I then decided to measure the difference between my NoPinz skinsuit and my skinsuit with my Roubaix jacket over the top. It was a windy day, but both efforts saw the same average wind exposure due to the circular track.
Wearing my jacket and skinsuit and averaging 35.7 km/hr my required power was 226 W. That back calculates to a CdA of 0.31 m². After riding in that setup for 10 minutes, I took the jacket off (so just skinsuit) and rode at 36.1 km/hr with a power requirement of 216 W - CdA back calculated as 0.282 m². So, lower watts and rode faster!
That's approximately a 2-minute saving over 40 km at the same power output.
Third Test: Aero Accessories
On a third day, I decided to try another test. I got some Rule28 aero socks and aero gloves and wanted to test these. So, test 1, was a new NoPinz (Sonic) skinsuit with regular cycling socks and no gloves. Test 2, I changed into the aero socks and gloves.
Test 1 I rode at 37.1 km/hr for a power requirement of 230 W. Back calculated CdA of 0.277 m². Test 2 I rode at 38.0 km/hr for a power requirement of 230 W. Back calculated CdA of 0.256 m². Or, an equivalent of a 14 W saving at the same speed.
Rule28 tested their socks alone in a wind tunnel at 10.5 W; our result of 14 W includes gloves, so the gloves appear to add approximately 3-4 W on top. That translates to about 1.5 minutes saving over a 25-mile TT at the same power. Which is a sizeable chunk of time to save without any additional physiological cost.
What Actually Matters
Worth noting: these aero gains matter most when you're exposed to the wind - during attacks, accelerations, small breakaways, and final sprints. While sitting in a 30-rider bunch, the majority of your aerodynamic drag is cancelled out by the riders in front, so these savings aren't relevant. But for masters racers riding in breaks of 3-4 riders, or anyone doing solo efforts, this is where aero wins races.
The Bottom Line
That's testing done (unless anyone wants to send me anything to test -- I've paid for all the clothing so far), and at moderate speeds (32 - 38 km/hr) there's substantial savings to be made by wearing the correct clothing.
For slower riders trying to get faster, aero is often the most cost-effective investment after training. And now you know what actually works.
Want to know what your power and aerodynamics actually translate to in race speed?
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