Video: How much aero difference does cycle clothing make?

Specialized looks at the aero performance of cycle clothing in their wind tunnel, and finds quite a big difference

by David Arthur   June 9, 2014  

Aero is everything, claim Specialized, who last year built their own wind tunnel at their Morgan Hill, California headquarters to allow the design team unlimited access to a very important tool in the study and development of producing aerodynamic bikes and products.

In between designing new bikes, they’ve been publishing videos to Youtube such as the recent “to beard or not to beard” video, looking at whether facial hair makes much difference to your aerodynamics. In their latest video they’ve looked at the more important issue of what impact your cycle clothing has to your aerodynamic efficiency.

You, as opposed to your bike, account for about 80% of the wind resistance you face when cycling, so as well has having a good position that minimises your frontal surface area, the clothing you wear can make a difference. But how much difference exactly? That’s what the Specialized video reveals, and the findings are interesting.

Mark Cote and Chris Yu, Specialized's aero research and development guys, look at the difference between casual club clothing and form fitting clothing. They've not only looked at the differences with summer short sleeve jerseys and shorts, but long sleeve winter clothing, the sort of clothing we in the UK spend a good chunk of the year in.

The first test, with a wind speed of about 50kph (31.25mph), reveals close-fitting winter clothing and long-sleeve jacket to be worth 83 seconds over 40km (25 miles). That’s a significant difference, and if you extrapolate that to a 100km or longer ride you’d certainly get to the cake shop a fair bit sooner.

Moving onto a summer jersey, and the difference is even more significant. As well as switching from a club fit jersey to a race fit jersey, they also went down a size, from medium to small, to get an even closer fit. The same testing conditions reveal the form-fitting jersey to be worth 91 seconds over the same 40km distance.

Some interesting results there. Of course, it’s well known that tighter fitting clothing is faster; that’s why skinsuits are worn in time trials and racers try and squeeze into the smallest clothing they can get away with - like Bradley Wiggins wearing a size small skinsuit in the Tour de France despite being over six foot tall. We’re now seeing racers, especially sprinters, wearing skinsuits in stage races a lot more this year for the same reason, and you only need to look at the popularity of Castelli's Gabba, a stretchy, slim-fitting jersey designed for bad weather, to see the importance attached to be aerodynamic.

The difference between clothing this hugs the body like a second-skin and baggy clothing that billows in the wind is more than can be saved by fitting far more expensive aero products to your bike.

As Chris Yu points says: “We’re talking about a difference here that is more than race wheels. Think about that. Several thousand dollars to go into race wheels, or think about your kit a little bit.”

So, if these claims are to be believed, clothing makes a big difference. If you want to go faster, wearing a closer fitting jersey or jacket is a really easy way to reduce the resistance you have to overcome when pedalling, and it's a lot cheaper than a new set of race wheels. 

30 user comments

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I think they've rather exaggerated the differences with a slightly implausible speed -- 50kph for 40km is very close to record-setting territory Smile Drag varies as the square of speed, so the recreational cyclist doing 25kph will only experience a quarter of the drag (and get only a quarter of the benefit of a close-fitting jersey).

In fact, I think I'll use "improved aerodynamic efficiency" as an excuse for going slowly from now on Wink

posted by David Portland [88 posts]
9th June 2014 - 15:24

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I'd rather be comfortable and look less ridiculous and get to the cake shop a minute later. If such tiny issues bother a rider then they have no business eating cake anyway.

posted by Joeinpoole [231 posts]
9th June 2014 - 16:18

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Well, someone has to ask this... I wonder what the aerodynamic efficiency would be if the rider went that final extra step beyond second skin. Surprise

Come on, it's a private wind tunnel, I can't be the only person who would be curious to find out. It's science!

posted by bikebot [484 posts]
9th June 2014 - 16:23

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David Portland wrote:
I think they've rather exaggerated the differences with a slightly implausible speed -- 50kph for 40km is very close to record-setting territory Smile Drag varies as the square of speed, so the recreational cyclist doing 25kph will only experience a quarter of the drag (and get only a quarter of the benefit of a close-fitting jersey).

In fact, I think I'll use "improved aerodynamic efficiency" as an excuse for going slowly from now on Wink


yeah my thoughts as well

posted by muffies [16 posts]
9th June 2014 - 16:27

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Apart from the terrifying thought of a naked cyclist in a wind tunnel (put me off my afternoon cup of tea)..

Who goes out in a 30mph wind... I'd be blown off the bike...!

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posted by nemysys [38 posts]
9th June 2014 - 16:45

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I found it interesting.. I need to do the maths on it, but 50kmh for 40km, is only 48mins riding.

If I look at my racing, I tend to compete for an hour or an hour and ten minutes, at averages between 40 and 45kph. Therefore, whilst the benefits aren't as big as claimed here, they are still significant enough to think about.

Problem is that I am already wearing form fitting kit... so really, all this is telling me that I am actually a minute or so slower than my loose jersey wearing competitors.

posted by Jimmy Ray Will [247 posts]
9th June 2014 - 16:56

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bikebot wrote:
Well, someone has to ask this... I wonder what the aerodynamic efficiency would be if the rider went that final extra step beyond second skin. Surprise

Come on, it's a private wind tunnel, I can't be the only person who would be curious to find out. It's science!

Michael Hutchinson mentions this in his book - bare skin is not faster than lycra on skin, to everybody's relief....

posted by 3cylinder [61 posts]
9th June 2014 - 17:19

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The best way of improving is not to sit up right with your elbows locked straight and your knees out like all the sportive Farmer Giles twonks I see on the road all the time.

The rider featured is better but still too high to be really efficient. Practice getting on the drops more often. Flat back. Wrists parallel with bottom bars and elbow forming 90°. Shoulders loose. It'll add at least a mile per hour to general speed.

Silly me. You're probably right....

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posted by MercuryOne [1052 posts]
9th June 2014 - 18:00

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David Portland wrote:
I think they've rather exaggerated the differences with a slightly implausible speed -- 50kph for 40km is very close to record-setting territory Smile Drag varies as the square of speed, so the recreational cyclist doing 25kph will only experience a quarter of the drag (and get only a quarter of the benefit of a close-fitting jersey).

In fact, I think I'll use "improved aerodynamic efficiency" as an excuse for going slowly from now on Wink

True, but drag is a drag. I think the moral of this story is that, if you're going for maximum performance, you need to look at your clothes before you start looking at shiny wheels.

posted by Gordy748 [83 posts]
9th June 2014 - 19:08

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MercuryOne wrote:
The best way of improving is not to sit up right with your elbows locked straight and your knees out like all the sportive Farmer Giles twonks I see on the road all the time.

The rider featured is better but still too high to be really efficient. Practice getting on the drops more often. Flat back. Wrists parallel with bottom bars and elbow forming 90°. Shoulders loose. It'll add at least a mile per hour to general speed.

I think the point was around a "normal" riding position. The way he is setup in the red is actually pretty low as he is only on the hoods. If he bends elbows would be not much different from many a pro.

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posted by koko56 [317 posts]
9th June 2014 - 21:03

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Put a stripe on it and you go ever faster!!

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posted by MamilYG-UK [4 posts]
9th June 2014 - 21:38

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Bah, I'll stick with the rain cape, if the weather gets really bad I can always fit the massive fairing/rain cover onto the Bakfiets.

posted by drfabulous0 [282 posts]
9th June 2014 - 21:41

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nemysys wrote:
Apart from the terrifying thought of a naked cyclist in a wind tunnel (put me off my afternoon cup of tea)..

Who goes out in a 30mph wind... I'd be blown off the bike...!

Well, technically speaking, you're in a 30mph wind every time you ride at 30mph. Those air particles that you're smashing in to as you barrel along have the same effect as air particles in a 30mph wind hitting you while you're standing still..

As for who goes out in high winds, well, I commute by bike all year round, and I've ridden in 25 mph+ winds a few times (with gusts far stronger than that), and it was hard work. Really hard work. And not much fun. But I did feel an unusual sense of achievement at making it home, which is unusual for a 10 mile bike ride.

posted by adrianoconnor [41 posts]
9th June 2014 - 22:54

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Gordy748 wrote:
David Portland wrote:
I think they've rather exaggerated the differences with a slightly implausible speed -- 50kph for 40km is very close to record-setting territory Smile Drag varies as the square of speed, so the recreational cyclist doing 25kph will only experience a quarter of the drag (and get only a quarter of the benefit of a close-fitting jersey).

In fact, I think I'll use "improved aerodynamic efficiency" as an excuse for going slowly from now on Wink

True, but drag is a drag. I think the moral of this story is that, if you're going for maximum performance, you need to look at your clothes before you start looking at shiny wheels.

Indeed:
http://flocycling.blogspot.co.uk/2012/11/flo-cycling-cycling-wheel-aerod...

If you're saving 83 seconds over 40km @50kph, you're saving a lot more time at 25kph with the same improvement

posted by olic [9 posts]
9th June 2014 - 23:19

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The most significant thing : it doesn't have to cost anything to buy a smaller top, if you are buying one anyway, but it will save all the flappiness. And get low!

posted by edster99 [150 posts]
9th June 2014 - 23:58

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So which is faster Red or Fluorine?


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posted by bikeboy76 [1233 posts]
10th June 2014 - 1:03

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This is great news for me - I can be overweight and maintain better aero because my clothing will be too tight.

Give me more cake...

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posted by andylul [412 posts]
10th June 2014 - 8:58

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If I account for 80% of resistance, maybe I should lose some body mass and observe Rule #5

posted by Konstantine [13 posts]
10th June 2014 - 8:58

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I've been using the 'TWO SIZES TOO SMALL' principle for years....who'd have thunk I was ahead of the boffins on that one... Cool

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posted by The _Kaner [396 posts]
10th June 2014 - 9:25

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David Portland wrote:
I think they've rather exaggerated the differences with a slightly implausible speed -- 50kph for 40km...

What about cycling at 30kph into a 20kph headwind?

posted by Nick T [777 posts]
10th June 2014 - 9:32

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Konstantine wrote:
If I account for 80% of resistance, maybe I should lose some body mass and observe Rule #5

... or buy a recumbent ...

Wink

posted by adrianoconnor [41 posts]
10th June 2014 - 9:40

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This is good news, I stopped working out a few years ago and just started buying smaller Tshirts.

posted by rhodrigo27 [7 posts]
10th June 2014 - 10:35

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rhodrigo27 wrote:
This is good news, I stopped working out a few years ago and just started buying smaller Tshirts.

Maybe the t-shirts just seem smaller Laughing

posted by bikebot [484 posts]
10th June 2014 - 13:47

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Have I misunderstood here, but doesn't the article say riding 50kph winds over a distance of 40kph NOT riding at at 50kph for 40kph??

posted by MikePrice [2 posts]
10th June 2014 - 14:32

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MikePrice wrote:
Have I misunderstood here, but doesn't the article say riding 50kph winds over a distance of 40kph NOT riding at at 50kph for 40kph??

The wind tunnel was creating a 50kph wind, which is exactly the same as riding at 50kph in still air. As is riding at 20kph into a 30kph headwind.

Obviously if it's a tailwind then you'll be wanting the baggiest jersey you can lay your hands on Wink

posted by David Portland [88 posts]
10th June 2014 - 15:40

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"wind speed of about 50kph (31.25mph),"

And who exactly can sustain 31 mph for an hour - never mind two - upright, on the hoods, on a weekend cake ride?

It's just marketing bollocks. Lots of people want to believe it, so they can buy some new kit. Like the race wheels that cost "several thousand dollars" (!). If you're not racing it's purely an indulgence - which is fine, but you're not fooling anyone.

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posted by Simon E [1940 posts]
10th June 2014 - 21:14

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"83 seconds over 40km (25 miles). That’s a significant difference".

It is???? Ignoring the unlikely speeds, what this proves is "Wear whatever you like. It don't make no difference".

83 seconds in a race? Sure. In your life? No.

Ride your own ride

posted by CanAmSteve [124 posts]
10th June 2014 - 21:21

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Sounds like they kept increasing the wind to get the results they wanted without considering how realist they were going be!

posted by MikePrice [2 posts]
11th June 2014 - 1:39

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It may well be in the video, but I can't be arsed watching that...

'The first test, with a wind speed of about 50kph (31.25mph), reveals close-fitting winter clothing and long-sleeve jacket to be worth 83 seconds over 40km (25 miles). '

as compared to....what, exactly??

'a distance of 40kph' in the comments gets my pedant senses twitching even more.

posted by andyp [850 posts]
11th June 2014 - 8:53

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David Portland wrote:

Obviously if it's a tailwind then you'll be wanting the baggiest jersey you can lay your hands on Wink

Presumably in a strong tailwind (until you're cycling fast enough to feel wind on your face!) one really should be riding sitting up, arms straight, etc?

posted by Al__S [506 posts]
11th June 2014 - 10:52

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