New wind-tunnel tests find surprising gains in cycling efficiency from leg-shaving


#1

[Permalink]


#2

7%?

Really? That’s a lot. A whole lot.

Course negative replications are very hard to publish, so I suppose it will stand.


#3

I prefer to look at it the other way… leaving the hair on makes my bike ride 7% more difficult which means I’m more of a badass.

I suspect the end result of this research is more riders will swap out their shorts for pants, rather than shaving everything off.


#4

There also may be a subset of men who now feel free to shave their legs, under the pretense of “oh, it’s just for cycling.”


#5

This article is about upending the “conventional wisdom” by doing science, not leg shaving. Curiously, the “conventional wisdom” came from some lousy science. There is so much of “a study showed that…” considered to be the unassailable truth, when it turns out that most of the studies are unrepeatable flukes.

I hope this sort of thing happens more and more, to get the scientific method back into science.


#6

Body shaving definitely works to reduce times in competitive swimming.


#7

But water is kind of denser than air, isn’t it? And is 7% a feasible improvement even in swimming?


#8

7% is very reasonable. You just have to factor in really hairy legs.


#9

Isn’t… This… why competitive cyclists shaved their legs for decades?


#10

Turbulence and boundary layers and drag and various odd effects named after people like Coanda and Bernoulli etc… there’s a lot more to it than just density! However, every competitive swimmer I know who did the experiment got faster times after shaving, regardless of the mechanism (I swam for about ten years when I was young, mostly 50m breaststroke and 100m IM.) There’s a paper about the metrics here.


#11

Science is really tackling the pressing issues of today!


#12

I believe you! But 7% in water, yay or nay? :smile:


#13

Technology has come a long way from 1987… the bikes and the riders are far more aerodynamic now, so I expect the tentpole effect – maybe hair wasn’t a big enough issue compared to the wide handlebars, non-aerodynamic tires, and blunt frame tubes, but now those things have been improved, hair tends to dominate more. What might have been a 1% improvement in 1987 might be a 7% improvement today.


#14

Didn’t Beijing get something a percent or more just from making the pool one meter deeper than usual?


#15

Other supposed reason… hair gets in the way of potential road rash healing.


#16

My understanding had been that it was largely about road rash being theoretically less painful.


#17

That’s probably closer to my typical cycling clothes than the MAML outfit in the story is - long hair, sometimes a beard, wool sweater, jeans…

Looks to my like that bike is a pretty good fit for Chewie, incidentally.


#18

The most widely cited test was a 1987 study for Bicycling magazine by engineering professor Chester Kyle, one of the pioneers of cycling aerodynamics. He found that leg-shaving reduced drag by 0.6 per cent, enough to save about 5 seconds over the course of one hour at the brisk speed of 37 kilometres per hour. At slower speeds, the savings would be less.

Given that meagre benefit

Meagre? No. Even that result makes it worthwhile, 0.6% less drag at the highest levels of competition is serious. 5 seconds is 5 seconds & that’s a long time between racers as far as finishing times go.

But 7% is definitely better.

Besides, you have to shave to race (road). I did.

The waves of scorn you would have to ride through would cost you way, way more than 15 watts or 79 seconds an hour, if you chose to show up all hairy.


#19

So if I shaved one leg and not the other, would I go in circles?


#20

Except the as-described 1987 experiment didn’t include handlebars, frame, and tires. It say a fake leg in a mini wind tunnel.

More speculation - glued on hair probably isn’t oriented the same was a natural hair, doesn’t bend in wind the same way, etc.