The curious case of the cyclist’s unshaven legs

http://www.theglobeandmail.com/life/health-and-fitness/health/the-curious-case-of-the-cyclists-unshaved-legs/article20370814/

by soundsop • 12 years ago

280 80 12 years ago

theglobeandmail.com

sjackso2• 12 years ago

The problem in the research community is that scientists have little incentive to duplicate earlier work just to check if it’s correct. Many journals have explicit policies forbidding the publication of work that attempts to replicate previous experiments.

This drive for unending novelty in the sciences is a shame on many levels. The good and useful work of duplicating and verifying results goes undone, and scientists are driven ever more forcefully towards designing studies only on the basis of what will attract grant agencies.

Duplicating major results carefully would be useful to the scientific record. Trying things that will probably fail, and then publishing negative results, would be useful too. But, for most researchers, doing this useful work appears to be career suicide.

rgejman2• 12 years ago

There are two problems, only one of which is addressed by duplication.

1. The original study may be plain wrong. Author 1 claims to describe phenomena X, author 2 can't find any evidence for X using the exact same methodology.

2. The original study is wrong because the methodology is bad, interpretation is incorrect, reagents are not specific, techniques are not clean, etc.

There's a strong argument to be made that it is more important to do orthogonal work which indirectly verifies the original results, as opposed to simply trying to reproduce the original work. This solves both #1 and #2.

The paper cited in the article is a great example. Gluing hair onto a plastic leg and putting it in a miniature wind tunnel is probably an exercise in bad methodology—but they might have still gotten the right result for their experiment. And that's useful because now we know that there may be something different about either plastic legs vs. real legs or miniature wind tunnels vs. big wind tunnels. This is a trite example, but it should be clear how this might be more important in other studies.

epistasis2• 12 years ago

I've never encountered a field in science where fundamental results aren't sufficiently replicated by other labs.

That nobody spent $500-$2000 to estimate leg hair drag probably speaks more about people not wanting to be caught measuring leg hair drag than about the entire field's tendency to replicate findings. It's also really weird for people to consider $500/hour tunnel time to be expensive for a sport with as much money as cycling.

Really, I thought it was weird, and probably inappropriate, to mix in so much of an outsider's amateur and unsopported opinion about science into an otherwise interesting story about leg hair drag.

If there's a serious story somewhere about results not getting replicated when they should in many fields of science, I'd like to hear about it. There's often stuff on the fringe, but any serious result will be replicated soon. Take, for example, the acid-bath stem cell retraction from not long ago. Where else are important results not replicated? The Higgs? It's a baffling perspective.

thaumaturgy• 12 years ago

If there's a serious story somewhere about results not getting replicated when they should in many fields of science, I'd like to hear about it.

Actually, there is! It's been referred to as "the decline effect", and it's fascinating.

The New Yorker published an article about it a few years ago (http://www.newyorker.com/magazine/2010/12/13/the-truth-wears...). It has resurfaced in popularity a couple of times. It was written by disgraced journalist Jonah Lehrer, but later independent investigation failed to find any fault with the article he wrote (http://www.lastwordonnothing.com/2012/11/05/jonah-lehrer-nat... -- worth reading because it includes statements from scientists on Lehrer's article).

So far, my favorite explanation is the direct, obvious one, which is that we're sometimes -- perhaps more often than we'd expect -- falling victim to statistics. Given the very large number of experiments and studies being conducted everywhere, and the selection for positive results, statistical anomalies are being accidentally selected for and then not being extensively enough re-evaluated much later.

The article discusses that as a possible explanation, but the journalist does his job, igniting reader interest, by suggesting the effect somehow "defies the laws of statistics". I favor the simpler explanation, which is that our meat brains simply underestimate the vast number of ways in which statistics would like to bugger us.

Some of the things that both you and the parent commenter mention are discussed in the article. For example:

Jennions, similarly, argues that the decline effect is largely a product of publication bias, or the tendency of scientists and scientific journals to prefer positive data over null results, which is what happens when no effect is found.

and

Richard Palmer, a biologist at the University of Alberta, who has studied the problems surrounding fluctuating asymmetry, suspects that an equally significant issue is the selective reporting of results—the data that scientists choose to document in the first place.

(aside: I'm not one of HN's vocal "science is junk" members. I love science, or, at least, I like to admire its butt (http://explosm.net/comics/3557/). I don't believe there's something fundamentally wrong with the scientific method. But, I do think more emphasis needs to be placed on repeatability of experimental results over longer periods of time, and I hope that this will become more of a trend as the world economy continues to grow.)

DanBC• 12 years ago

Why Most Published Research Findings Are False: http://journals.plos.org/plosmedicine/article?id=10.1371/jou...

Everything We Know Is Wrong http://www.bbc.co.uk/programmes/b04f9r4k

Malarkey73• 12 years ago

Its a very common phenomenon in science that a finding is published in a glamour journal e.g. Nature/Science and then if not immediately controversial e.g. acid bath stem cells, it becomes very difficult to publish something contradictory.

Journal referees will set the bar for such findings very very high...and you are quite likely to be refereed by the original author or their friends.

I know this to my cost having gone to extraordinary lengths to publish something slightly contradictory in a far lower impact journal than the work deserved.

learnstats22• 12 years ago

Results which generate international headlines tend to get replicated in the hope of further headlines.

This does not represent the experience of many millions of scientists.

You should consider that all science is on the fringe - the purpose of academic science is to research novel ideas.

TheCondor• 12 years ago

I agree with your sentiment but there is one flaw, cycling is a dirt poor sport that has traditionally been very blue collar. There are racers in the Tour that make less than $30k per year, live at home with their parents in the off season and wrench as mechanics. There are only a small handful of them that make "pro athlete" money.

That's a lot of money to most of them, especially when they can be testing fit and position which have well known advantages to both aero and power output AND they already shave.

Xcelerate• 12 years ago

I agree. You can't even publish negative results, although the data would be incredibly useful to the scientific community. The whole point of science is consistent replication to aid prediction.

Some rich person needs to start a program incentivizing this kind of work.

ansgri• 12 years ago

It seems more likely that some rich person already have duplicated some "key" discoveries and is happily reaping the benefits of knowing what does work, without making much noise of it.

baddox• 12 years ago

It seems like a drive for unending novelty would cause people to want to gather evidence that contradicts well-established studies. That's by definition novel, and would probably result in good press.

collyw• 12 years ago

I would like to think that there is a self correcting element to this. If someone produces genuinely high impact novelty science, others will want to build on that - and will end up replicating it anyway. If it isn't possible to replicate or isn't important, then it will be forgotten about.

I agree about publishing negative results. The experiments that don't work, but might have had a high impact will likely be repeated, as no one knows it hasn't been tried.

lutusp• 12 years ago

I agree about publishing negative results.

If only science publishers would agree. But they're in a money-making business and novel results, "breakthrough" results, even if unverified and soon to be disproven, sell journals much more efficiently than null results or falsifications of earlier work.

Balgair• 12 years ago

https://en.wikipedia.org/wiki/John_P._A._Ioannidis

"Ioannidis's 2005 paper "Why Most Published Research Findings Are False"[5] has been the most downloaded technical paper from the journal PLoS Medicine.[8] A profile of his work in this area appears in the November 2010 issue of The Atlantic.[9] The Atlantic article notes Ioannidis analyzed "49 of the most highly regarded research findings in medicine over the previous 13 years". In the paper Ioannidis compared the 45 studies that claimed to have uncovered effective interventions with data from subsequent studies with larger sample sizes: 7 (16%) of the studies were contradicted, 7 (16%) the effects were smaller than in the initial study and 31 (68%) of the studies remained either unchallenged or the findings could not be replicated.[5]

Statisticians Goodman and Greenland agreed that "many medical research findings are less definitive than readers suspect" but disputed his headline claims as unsupportable by the methods used.[10][11] Ioannidis responded to this critique[12] and other researchers have generally supported the general thrust of his findings.[13][14] Ioannidis' work is focused on improving research design standards."

nl5• 12 years ago

The Specialized video[1] is worth watching - it's pretty funny how astonished they were over how much power it saved.

If you are interested in this, then the book Faster: The Obsession, Science and Luck Behind the World's Fastest Cyclists by Michael Hutchinson is really good (and very well written).

He notes that human intuition about aerodynamics just isn't very good (you have to test) and that the current state of the art is no longer wind tunnel testing but computational fluid dynamics (CFD) followed by testing with a power meter on the road.

CFD lets designers iterate much quicker on designs and try things outside the norm (avoiding the local maxima problem). Power meters plus riding is better than wind tunnel testing because things like variable cross winds are very hard to test in wind tunnels.

[1] https://www.youtube.com/watch?v=DZnrE17Jg3I

[2] http://www.amazon.com/Faster-Obsession-Science-Fastest-Cycli...

nether3• 12 years ago

The annoying thing with CFD with analyzing viscous phenomena is the question of reproducibility. Flow structures in this regime (low Re, that is low speed and small length scales) are notoriously sensitive to surface defects, e.g. the hairs being analyzed. A CFD sim will show nearly the same results for a given problem, and current CFD lacks the fidelity to really model tiny turbulent features at these scales as well as the necessary fine surface definition. Experimental results may show drastically different results depending on the minute upstream flow variations, and surface quality: in this case, legs with hair/sweat/dust/oils could all trip the boundary layer to varying degrees. Stories abound of clumsy wind tunnel technicians who left skin grease on a wing model for a low-speed test and neglected to polish it with a rag...

nl5• 12 years ago

Yeah.

Faster talks about a certain dimpled TT helmet[1], and how it would probably work really well if your head rotated continuously while you rode.

[1] The book doesn't name which one, but this is the only dimpled TT helmet I know of: http://www.louisgarneau.com/in-en/product/826916/1405156/Vie...

justinator2• 12 years ago

One thing they don't tell you in the Specialized video is that they're not testing someone who is pedaling. There's some much more turbulence from just moving your legs, that shaved or not shaved makes almost 0 difference. No one is coasting for 40 km. Even the time savings they do cite in perfect, almost platonic conditions is seconds over hours of riding.

Bicycling manufacturers always skew the numbers for how much savings (time, watts, whatever) their new top of the line frames will give you. It's all smoke and mirrors.

derekja• 12 years ago

ah, that makes much more sense. If they had been pedaling I was wondering how they got rid of bias since it would be pretty hard to blind the rider as to whether their legs were shaved!

nl5• 12 years ago

One thing they don't tell you in the Specialized video is that they're not testing someone who is pedaling.

This isn't true. Watch the video - he's pedaling when they test.

There's some much more turbulence from just moving your legs, that shaved or not shaved makes almost 0 difference.

That's almost exactly wrong. It's true that pedalling creates turbulence, but the speed your legs move and the turbulence created by that movement is almost entirely disguised by other effects.

For example, the fact a bike is asymmetrical (because of the drivetrain) is a much bigger factor than turbulence because of moving legs.

It is important that testing includes pedaling, because there can be particular positions that work better on some bikes (or for some people) than others.

But in this case the testing used sensible protocols and the difference is a real thing.

Bicycling manufacturers always skew the numbers for how much savings (time, watts, whatever) their new top of the line frames will give you. It's all smoke and mirrors.

That may be the case, but all Specialized is selling here is their aerodynamic expertise (at least until you can buy a Specialized razor blade).

nether3• 12 years ago

One thing they don't tell you in the Specialized video is that they're not testing someone who is pedaling.

Yes they are. Chris Yu (running Specialized's wind tunnel; the only bicycle company with their own) is a CalTech/Stanford trained aerodynamicist and competitive cyclist. Give him some credit.

idlewords2• 12 years ago

Man, I wish they had made him shave that goatee.

Shivetya• 12 years ago

I had thought that it was already established by swimmers that hair was a detriment to speed. Why would it be surprising to cyclist? I do ride, but not competitively so I will keep the razor to my face only, thank you.

electromagnetic• 12 years ago

Exactly this, its already well established that skin hair causes drag. Firstly it acts as insulation. Secondly, it works remarkebly well to evaporate sweat and being originally savanna dwelling primates that endurance hunted our pray it would only make sense that drag not only exchanged for, but contributes directly to our ability cool our body temperature.

sp332• 12 years ago

It's a surprise because a previous study already tested and found a very small result.

chrisbennet2• 12 years ago

Yes, it was "already established" that hair caused drag.

That is why this study was so surprising. They found that hair decreased drag.

nether3• 12 years ago

The gremlin that is low Re, viscous drag. This is how cacti work; the needles slow surrounding air to reduce moisture loss through convective evaporation.

bch• 12 years ago

Massage and reducing wear-and-tear in event of crashing are the best most plausible reasons I've heard for it. I'd never heard anybody seriously thinking it reduces drag in a meaningful way.

(Edited to describe my experience, per "let's not read the article" comment).

mosselman5• 12 years ago

Yes, lets all not bother reading articles before commenting from now on.

mosselman5• 12 years ago

A good thing that 5-6 people is a statistically significant number of participants....

eru2• 12 years ago

It can be, if the effect is big enough compared to noise. (In medicine you usually have much more noise, that's why you need more participants.)

mosselman5• 12 years ago

I appreciate that in medicine it can be. But this is not medicine. In this case the 'research' was obviously done by first letting someone cycle WITH hair, then they were shaved (with time to recover I imagine) and then they tried again. I say 'obviously' because this little participants is not enough because you'd need more people to be able to compare means in performance differences.

The problem I see however is that after being shaved the participant would feel faster and thus behave faster. A sort of placebo effect if you will. At the same time, the cyclist-cultural effect of being 'unshaved' in the first test would make them feel sluggish. The same effect as seen in experiments where participants are presented with negative messages vs positive messages and asked to perform tasks. The participants exposed to negative messages, as expected, perform poorly in comparison to the other group.

In conclusion, I feel, that this 'research' can only be used as something to base you hypothesis on, but it is in no way conclusive in its current setup. You'd need to have random groups of cyclists, some of whom are, to begin with, shaved, and some who are not. It would maybe be easier not to use cyclists in order to find a diverse enough set of participants. Then again I don't know how many regular cyclists go around unshaven.

bildung• 12 years ago

The number of people needed to archieve statistically significant results more or less solely relies on the size of the effect that gets measured[1]. It's actually not unusual to design experimental studies with just a single person - provided the "treatment" (shaven legs in this case) are reversible. Then you just have to make repeated phases with and without treatment , e.g. ABABAB or even ABACABAC if you have an alternative treatment you want to compare the results with.

[1] If you design a study you can actually start from the other end: If you can estimate the size of the effect to be measured, you can calculate the number of people needed for significance beforehand.

mosselman5• 12 years ago

Thanks for the explanation. That makes sense.

andyjsong• 12 years ago

Interesting, I wonder how dramatic the effect is with swimming, there are swim flumes like this https://www.youtube.com/watch?v=feUhyCklHL0. It's usually used to analyze your stroke, but maybe if you put a bar in there to hold on to and test unshaven vs. shaven.

shiloa• 12 years ago

As a former swimmer, I can say that shaving is not only done for drag. Once shaved and in the water, even while casually swimming in warmup, I would feel as if I'm actually floating better. We'd call the "feel for the water" or something similar. It's hard to describe unless you've experienced it, but I suppose it has something to do with a newly exposed layer of skin in contact with the water.

And, of course, there are also the benefits of less drag and psychological placebo effect.

cecilpl• 12 years ago

As a former national-level swimmer, I always shaved my legs/arms and tapered my training for a big meet twice a year.

I found that combination to lower my times by about 1 second per 50m, or about 5%. I don't know how much of that is attributable to the shaving, but I will say it helped me "feel" way faster.

anvarik• 12 years ago

Reminds me Hitchhiker's Guide to Galaxy, and those planet creators

serf• 12 years ago

a family friend, the aerodynamicist Chester Kyle, was mentioned in this article. He was a lecturer at Long Beach State (I think) and did practical wind-tunnel testing with my father (an engineer and manufacturer) on bicycle shapes for many years.

He pushed the edges of conventional design, and participated in the human powered vehicle races quite a bit.

That's fantastic; I never thought I would hear about him on here.

vhost-• 12 years ago

Does anyone know why wind tunnel use costs $500 an hour? Electricity bill?

nodata• 12 years ago

Because someone will pay $500 per hour.

rasz_pl• 12 years ago

Setup costs.

jtheory• 12 years ago

That's my guess -- they must be quite expensive to build, with quite a bit of specialized hardware involved (not exactly off-the-shelf stuff!), and highly-specialized people to run it ...but then only one experiment can use the whole shebang at a time (including setup/teardown time), so they can't spread out the costs across lots of concurrent users.

Too2• 12 years ago

It's not just a big fan, they also come with all the measurement equipment.

idlewords2• 12 years ago

It bugs me that the test is run with the vertical wheel supports in place. It's conceivable that they alter airflow in a way that affects how it goes over the cyclists legs.

But maybe I don't fully understand the experimental setup. I'm basing my comments on what I see in https://www.youtube.com/watch?v=DZnrE17Jg3I

IvyMike• 12 years ago

They are claiming "it contradicts previous results", but certainly the savings must depend on the athlete's pre-shave hirsuteness. Unless they controlled for that, the previous results could have just been because of a relatively smooth group of subjects.

MatmaRex• 12 years ago

The article states that the previous results didn't involve any subjects at all, but a "fake lower leg in a miniature wind tunnel with or without hair glued onto it".

ccozan• 12 years ago

I speculate here that this could be a second reason why we lost our big ape hair. The preferred method of hunting was running after prey until it fell/slowed down - due to the fact that, unless other animals, man can run and hold the mouth open, thus eliminating the excess heat + higher oxygen flow. Having less hair than the prey made us run otherwise faster while on lower enery requirements.

beseku• 12 years ago

At the speed we run, it would make no difference I would imagine. The benefits of shaving your legs only really come into effect for cyclists at the pro level ... those of us who can manage a steady 25km/h see far less benefit.

I always thought it was an urban myth that it made you go faster, and that the real reason was that road rash was easier to treat.

kevin_thibedeau• 12 years ago

I am not a competitive cyclist but remove the hair on my legs with a depilator in the Spring because my leg pelt retains too much heat in the Summer. There is a noticeable improvement in cooling after it is done.

While not the most pleasant process, it avoids stubble and the delayed regrowth means the new hair is sufficiently long to begin providing warmth just in time for when cooler Fall temps arrive. I always considered that to be the real reason why the pros do it with road rash being of secondary concern. Those with shorter leg hair just went along and copied their hairier peers.

jrapdx3• 12 years ago

I think it's healthy that this discussion expresses amazement, skepticism, methodological questions, and observations about competition for public media attention, and frequent instances of journals cynically manipulating publication for maximal sensationalism under a scientific patina.

Strictly my own imagination, but I'm anticipating the introduction down the road of the world's most advanced hair removal system that gives cyclists a big aerodynamic advantage proven by scientific tests. Yes buy the XYZ system and fly to victory! Wow, I really am jaded, but too many times we've seen it happen.

So much bad science obscures the good work because the latter doesn't make the news, it's far too boring to attract attention. It's the small incremental, tedious, repetitious, careful, persistent work that provides the real advances. Edison I think said, "we find 20,000 ways it doesn't work" and learn something every time we try.

I propose a simple set of remedies. Journals should give highest priority to publishing careful replications of prior studies, whether it's yes/no/maybe. Negative studies whether original or replications are give as much priority and those confirmatory. Novel associations are of course welcome if meeting standards of adequate power to discern something beyond quirky results.

Ultimately, the impact of hyperbolic claims about the meaning of research causes the greatest distortions of scientific process and progress. Journal editors can solve the great bulk of misinformation their journals promulgate. It's remarkably simple. All they have to do is issue an edict, all that authors can write about are the history, background, what they did and factual results of their work. These "rules" apply to observational and experimental work all the same. IOW it would be forbidden to draw conclusions about the what the outcomes mean, what is proven, or what "causes" what.

Sure giving context about past results is necessary and usefully informative, but conclusions are for we the readers to determine. If this was the case, suddenly the strident "answers" and premature incorporation of findings into practice will be sharply reduced. Hysteria will subside. We can then actually use our scientific talent to accomplish honest goals, and solve the real and daunting problems we actually have.

Perhaps this seems a radical view and maybe it is. It's not whether I'm right or anybody will make any of these substantial changes. It is about getting back to careful thoughtful scientific inquiry and reducing misdirected human energies.

ck2• 12 years ago

After 15mph a great deal of energy is used to overcome wind resistance.

I wouldn't have figured it to be so much but this doesn't seem so incredible to me.

Similar thing for swimming.

jpatokal• 12 years ago

Previous test: "leg-shaving reduced drag by 0.6 per cent"

New test: "The tests showed that shaving his legs reduced Thomas’s drag by about 7 per cent"

Yet the blurb says: ''Even more confounding was that the results contradicted earlier finding''. What's contradictory about those results? Be it 0.6% or 7%, shaving your legs clearly reduces drag.

ssanders82• 12 years ago

Previous test was not a significant amount, the new test was

UnoriginalGuy• 12 years ago

I believe that was a reference to the "insignificant difference" claims. 0.6% wasn't seen as significant enough difference so it became a "fashion choice" rather than an efficiency one.

Too2• 12 years ago

I find it odd that they only report the results in percent in the first place. Maybe the baseline drag of a rider back in the 80's was much higher than today, making 0.6% old the same amount of force as 7% new.

jamessb• 12 years ago

Specialized previously investigated the effect of shaving off a beard, and found that it had a negligible effect: http://www.bikeradar.com/us/road/news/article/specialized-te...

graemian• 12 years ago

If a cyclist invested the weekly time he spent shaving his legs in extra training instead, would he be better off?

pdxandi2• 12 years ago

Shaving your legs doesn't take much time at all. I race a few times a week (during the season) and shave once, at most twice, a week. Probably takes 10 minutes to shave. There's nothing I could do for 10 minutes a week that would improve my time by up to eight percent (most amateur cyclists already overtrain as it is). Not part of your question, but shaving is also largely about being able to treat road rash and avoid infection.

jmadsen• 12 years ago

Strange. When I was racing, we never thought about drag, except as a joke.

We shave because it helps reduce road rash when you go down on asphalt (slide easier) & easier to keep the wounds clean afterwards.

pdxandi2• 12 years ago

Exactly. I'm an active racer and have witnessed people get yelled at in the medic tent for not shaving their legs. Treating road rash is awful with leg air.

andygates• 12 years ago

And the fact that everyone else does it; it's a badge of seriousness.

"Reduce drag" is always the jokey reason I'd use for non-cyclists :)

jaynos• 12 years ago

Also, for cold weather riding and racing, applying embrocation (warming balm) is much easier without hair.

AndrewKemendo• 12 years ago

Exactly right. I raced in college and it was well known that shaving was for making it easier to deal with injuries/massage.

A bit of it is also in-group/out-group signaling.

erbo• 12 years ago

What's interesting here is that the practice of cyclists doing so goes back a century. By contrast, the fashion of women shaving their legs dates back primarily to around World War II, and the influence of pinup model Betty Grable. See: http://www.straightdope.com/columns/read/625/who-decided-wom...

shiven• 12 years ago

Compared to numbers from earlier studies (0.6), the new number (7) looks suspiciously like a floating point error arising from software/hardware issues!

myleskeating• 12 years ago

Relevant article on similar lack of reproducibility in cancer research.

http://www.reuters.com/article/2012/03/28/us-science-cancer-...

Summary: a team at Amgen discovers 47 of 53 "landmark" studies published in high-quality journals could not be reproduced. A team at Bayer did an internal review of programs they had initiated based on journal studies and found that less than a quarter of those findings could be reproduced.

Three very damning quotes: "Some authors [of the journal articles] required the Amgen scientists sign a confidentiality agreement barring them from disclosing data at odds with the original findings."

"'We went through the paper line by line, figure by figure,' said Begley. 'I explained that we re-did their experiment 50 times and never got their result. He said they'd done it six times and got this result once, but put it in the paper because it made the best story. It's very disillusioning.'"

"The problem goes beyond cancer. On Tuesday, a committee of the National Academy of Sciences heard testimony that the number of scientific papers that had to be retracted increased more than tenfold over the last decade; the number of journal articles published rose only 44 percent."

Academics are pressured to produce publications, not to produce science, and their studies are not always rigorous (not blinded to experimenters, etc.). People with high integrity and ability do produce good science that gets published, but unfortunately that appears to be the minority, even in highly prestigious journals.

So I'm curious: how would you fix it?

One thing the article mentions that might improve things is every journal dedicating one complete issue a year to reproducing the most influential studies of the year. Another could be getting a consortium of pharmas (who try to reproduce studies all the time, because if you're going to successfully make drugs you need the thing to work) to publish their internal data for the benefit of all. Does something like that exist?

The curious case of the cyclist’s unshaven legs

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