[slackline]

How citation distortions create unfounded authority: analysis of a citation network

[Fultonius]

That confirms exactly what I previously thought. 

[slackline]

Must be down to its rising Altmetric score as its not been published long enough to have been sufficiently cited and distort its own, unfounded, authority on the matter.

[slackline]

Physicists detect exotic looped trajectories of light in three-slit experiment

[slackline]

M. DelVicario et al/ (2017) The spreading of misinformation online. PNAS 113(3):554-559

[i.munro]

Possibly of interest to some.
Having been "skeptical" about the utility of chalk in bouldering for some time, last term I proposed an undergrad project last term to extend the work in http://gblanc.fr/IMG/pdf/li2001.pdf

Time pressure sadly meant that no "extending" got done but the students managed to repeat the chalk vs no chalk portion of the experiment, in this case using the max load that the test subject could hold.
Only eight subjects were tested but for all eight the coefficient of friction was lower with chalk.
"The average coefficient of friction without chalk was 0.62 +- 0.07 and with chalk was 0.54+-0.06"

[Muenchener]

Erm ... the first thing that struck me looking at that paper is that the apparatus shown bears no resemblance to anything one would actually do whilst climbing.

Surely one of the first things people learned trying to apply SCIENCE to rock climbing performance was that the tests and the apparatus have to be climbing specific. Exhibit A: handgrip dynanometers, irrelevance of.

Chalk use has been pretty much universal in high standard climbing for forty years, including a quarter of a century of world level professional competition, and a lot longer than that in weight lifting and gymnastics. I suggest that Occam's Razor fairly quickly disposes of "it's all been placebo all along" in favour of "ok, we haven't understood the mechanism by which it helps yet but this study at least helps us to discard one hypothesis".

[i.munro]

You raise 3 points there.

1) Specificity

 If you can suggest an  improved protocol ( assuming that there is such a thing as an English University next year and even more unlikely, that I still work at one) I'm happy to put that forward. However I fail to understand the problem here? ok the rock is being pulled away from the climber rather than vice-versa, for safety reasons, but otherwise it looks pretty relevant to me.

2) "We haven't understood the mechanism"

Climbing grip is a complex subject and friction probably plays only a small part. For example, I assume on incuts it's pretty irrelevant and even on typical slopers conformance (skin digging into rugosities) is probably more important. However friction is what chalk is generally believed to affect so that was investigated. Even then there is much this study didn't answer. I was hoping they'd look at the effect of humidity, temps and over a range of forces. However time pressure didn't permit this.    So yes there's a lot of work to do but the generally accepted argument is that chalk improves friction. If you have a hundred Grand or so to spare let me know & I'll get a Phd student to investigate the other aspects.

3) "high standard climbing"

Where objective evidence & what "everybody knows" conflict I tend to go with the former. I'd be in a strange job if I didn't.

[Muenchener]

1) Specificity

 If you can suggest an  improved protocol ( assuming that there is such a thing as an English University next year and even more unlikely, that I still work at one) I'm happy to put that forward. However I fail to understand the problem here? ok the rock is being pulled away from the climber rather than vice-versa, for safety reasons, but otherwise it looks pretty relevant to me.

I can't remember the last time I tried to support my weight with my hand & forearm arm pressed flat against a piece of rock (with my wrist strapped to it). Also, when route climbing - maybe to a lesser degree when bouldering - you have both sustained effort and mental state changing your metabolic state & causing fingertips to be sweaty. And sweat is a lot more slippery than water. Don't see any of that being simulated / attempted to be accounted for here.

Get the climbers sweaty then hang 'em from slopers, maybe?

Where objective evidence & what "everybody knows" conflict I tend to go with the former. I'd be in a strange job if I didn't.

You have no objective evidence that chalk doesn't help in a realistic climbing situation because you haven't tested one.

Your implied hypothesis is that *everybody* in a competitive environment over a period of decades has been doing something that is measurably harmful to performance, yet nobody has tried not doing it and found that they thereby perform better. Not to mention also saving [... weighs chalkbag ...] 200 grammes in the weight obsessed world of competitive lead climbing. I'm not buying it.

[i.munro]

The hypothesis that is genertally accepted is that chalk imroves friction. These results along with the paper I linked suggest that, at least in the range of temps, humidity and force measured that it does the opposite.

Possibly it has other effects. Maybe drying out the cells of the skin makes it more rigid and makes the skin mold to rugosities better. Who knows?

However I posted this in case anyone found it of interest. I can't be bothered discussing Climate Change with a Trump any futher.

[cjsheps]

"The average coefficient of friction without chalk was 0.62 +- 0.07 and with chalk was 0.54+-0.06"

Interesting study!

Not trying to diss, but with uncertainties included, those results heavily overlap. I'm also unsure as to whether such a setup would be particularly relevant to friction in climbing. Rock isn't uniform, and a lot of friction comes from "molding" to holds - all at very particular angles and forces (as mentioned earlier by others).

[mrjonathanr]

The hypothesis that is genertally accepted is that chalk imroves friction. These results along with the paper I linked suggest that, at least in the range of temps, humidity and force measured that it does the opposite

Experientially, chalk provides an experience of greater friction. How it does so is another matter. By suppressing sweat on fingertips, I imagine.

(PS 'skeptical' is an American spelling. If you are English, it's 'sceptical')

[tomtom]

Nice post and study Ian.

(hopefully in your support!) the problem designing an experiment to look at this is that if you want to make it 'realistic' then there are many many additional variables to consider (lets say, finger shape, skin condition, moisture, sweating, temperature, humidity, the match between the hold and the fingers, how chalk was applied, how much chalk was applied, what type of chalk was used etc.. etc.. etc..) that you have to accept a compromise - so folk say it is unrealistic. Or make the experiment so so so simple people will then not consider it realistic. A catch 22..

[abarro81]

I only skimmed the paper over the course of 2 min but... doesn't your study say that wet rock has almost exactly the same friction as dry rock? Given that that result clearly has absolutely no correlation with the realities of rock climbing I think it's safe to assume that the study is irrelevant from a rock climbing point of view.

[Muenchener]

Careful. He'll sulk and call you a Creationist or something similarly bizarre. 

[jakk]

My undergraduate project (a couple of years ago now) was an attempt to do a study like this in a climbing specific way. I threw together a sloper bar (flat wooden 2X4 effectively) floating on some load cells, made the angle adjustable to cater for different strengths and got people to hang near-maximum and slowly let off the effort until they suddenly slipped (so assuming some relatively constant actual friction coefficient, all that happens to hold a worse angled sloper is that the fingertips pull down more to maintain the same force angle against the hold. An experienced climber should then have enough control to gradually let off the force until the force angle gets too bad, friction goes and you slip off). It was of course pretty limited, very much a first attempt-type thing so not tons of data, not a bulletproof setup by any means, but the results I had did show that chalk is effective, at least for a ~5s hang on a wood bar in both sweaty and dry conditions.

The point really was to experiment with making a climbing specific version of this sort of experiment, rather than the imo non-climbing-specific ones that had previously been done, and in that respect I think it worked. Not a lot of time at the moment but can dig up some stuff if anyone's interested

[i.munro]

I abviously need to clarify a few points.

The study I linked above http://gblanc.fr/IMG/pdf/li2001.pdf isn't mine it's from 2001.

My students were asked to look at that paper and this one http://gblanc.fr/IMG/pdf/li2001.pdf
and try ro design equipment to cast light on the discrepancy in results. In particular to look at the effects of load as the 2 experiments were done in very different regimes. In the 2001 paper the tangential load is, presumably, a few Kg whereas for the fingerboard it must be a significant fraction of bodyweight.

The experiment they came up with, however was very similiar to the 2001 Birmingham paper , differering mainly in having a variable tangential load setup. They didn't have time to take many results, sadly, and didn't repeat the dry/wet test in the 2001 paper either.  I have posted the results that they did manage to obtain which are consistent with those found by the 2001 paper.

[Ian T]

Here's the SCIENCE behind 'sticky damp'. Maybe.

http://eprints.whiterose.ac.uk/42900/2/Lewis_42900.pdf

[i.munro]

Interesting! Thanks for posting.

[Fultonius]

The hypothesis that is generally accepted is that chalk improves friction.

Really? 

I thought most felt chalk made no difference or was detrimental to friction with dry skin?  I certainly noticed (back when I could hang the 45s on beastmaker) that a bit of spit to moisten the skin/clean of chalk with either no chalk, or the lightest dusting of chalk to dry any overly damp bits worked best. More chalk was certainly worse.

I think it's more than just sweat that's the problem - our skin produces oils too.

[Oldmanmatt]

The hypothesis that is generally accepted is that chalk improves friction.

Really? 

I thought most felt chalk made no difference or was detrimental to friction with dry skin?  I certainly noticed (back when I could hang the 45s on beastmaker) that a bit of spit to moisten the skin/clean of chalk with either no chalk, or the lightest dusting of chalk to dry any overly damp bits worked best. More chalk was certainly worse.

I think it's more than just sweat that's the problem - our skin produces oils too.

Absolutely. I wash my hands and use a damp rag when fingerboarding or climbing on wood.
But not on plastic or rock. Pretty sure the chalk helps there.


All posts either sarcastic, tongue-in-cheek or mildly mocking-in-a-friendly-way unless otherwise stated. I always forget to put those smiley things...

[i.munro]

I think it's more than just sweat that's the problem - our skin produces oils too.

No attempt was made to prevent the subjects sweating during our experiments.
Whatever components are normally present  in sweat were therefore present during our tests.

For the effects of preventing sweat chemically see:
http://link.springer.com/article/10.1007/PL00005666?no-access=true 

Somebody above mentioned the effects of fear on sweat rates  ( and possibly on it's composition) and we haven't investigated this - my employer frowns on dangling test subjects (even students) over large drops.

However if it's the case that there is some component  in "fear" sweat that can only be addressed using chalk and further assuming , as was argued earlier, that elite climbers fingers can accurately didtinguish frictional effects from all the other components of climbing performance then wouldn't we expect to see chalk used only on the upper section of highballs and not on lowballs, sit-starts and traverses.

[Oldmanmatt]

Are they out there?

https://arxiv.org/abs/1701.01109


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[Stu Littlefair]

I'm going to bet without clicking on that link that it's an Avi Loeb paper. If I'm right you owe me one million dollars


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[Stu Littlefair]

Click.... and sigh. Always aliens with that guy.


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