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Arrogant_Bastard


Nov 21, 2008, 11:34 AM
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Shoe Rubber Testing
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I know that shoe rubber is hardly a safety issue, but people seem so bent on their preferred shoe, dismissing all others, that I thought I’d post this up for some scientific critique. I came across this page on testing Spadout did on rubber from various shoe companies. Hardly extensive or well-rounded, it mainly comprised of comparing the static coefficient of friction for various rubbers. Typical weight on rubber on inclined plane deal.

http://www.spadout.com/r/climbing-rubber-test/

Some obvious issues I saw was the light weight used. I’d guess this would significantly favor softer rubbers. The temperature was held constant, and I know companies target an optimal temp, which could be different from company to company. There was also a minimum of different surfaces and contours tested.

Additionally, this doesn’t even touch on shoes, simply the rubber. It just caught my eye because I hear so much negative talk about Evolv rubber from 5.10 die hards, and here they are as the ‘stickiest’ in this particular test.


adatesman


Nov 21, 2008, 11:41 AM
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rockforlife


Nov 21, 2008, 11:42 AM
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Re: [Arrogant_Bastard] Shoe Rubber Testing [In reply to]
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Arrogant_Bastard wrote:
I know that shoe rubber is hardly a safety issue, but people seem so bent on their preferred shoe, dismissing all others, that I thought I’d post this up for some scientific critique. I came across this page on testing Spadout did on rubber from various shoe companies. Hardly extensive or well-rounded, it mainly comprised of comparing the static coefficient of friction for various rubbers. Typical weight on rubber on inclined plane deal.

http://www.spadout.com/r/climbing-rubber-test/

Some obvious issues I saw was the light weight used. I’d guess this would significantly favor softer rubbers. The temperature was held constant, and I know companies target an optimal temp, which could be different from company to company. There was also a minimum of different surfaces and contours tested.

Additionally, this doesn’t even touch on shoes, simply the rubber. It just caught my eye because I hear so much negative talk about Evolv rubber from 5.10 die hards, and here they are as the ‘stickiest’ in this particular test.

Clicky


rockforlife


Nov 21, 2008, 11:47 AM
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In reply to:
The weight (15 oz of steel)

Wow thats it, just seems like that wouldn't give you the best test results. But it was a constant so i guess that works.


shockabuku


Nov 21, 2008, 11:52 AM
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adatesman wrote:

Clicky! Smile

Oh, and thx... I'd been contemplating doing something similar and you've gotten me off the hook for it!

Thanks. You'd think as big of a post whore as AB is he'd be able to post a link by now. I guess that's what I get for thinking.Pirate


Valarc


Nov 21, 2008, 11:56 AM
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Arrogant_Bastard wrote:
Some obvious issues I saw was the light weight used. I’d guess this would significantly favor softer rubbers.

My thought was sort of the opposite - I was thinking a heavier weight might favor softer rubbers, since they are more prone to deform. I guess it depends on how soft "soft" is.

My other thought was that this isn't terribly applicable to climbing performance. Friction is, no matter what they taught you in high school, a lot more complicated than F = mu*N. In fact, that silly "independent of surface area" nonsense breaks down in all but the simplest cases, and even breaks down in those simplest cases sometimes (I ran into this one a few years ago when I was TAing undergrad labs). So looking at the point where a chunk of rubber starts to slide on a smooth surface is, IMHO, not very useful. It's telling you nothing about how that rubber would stick to actual, featured rock.

In my limited personal experience, "softer" rubbers tend to be stickier from a smearing perspective, because they can deform more to the contours of the stone, putting more surface area in contact. The tests seem to show the exact opposite of my personal experience with Vibram vs. Stealth C4, where I found Vibram to be absolutely lousy at smearing compared to the Stealth.

I'm honestly a bit disappointed to see this study coming from a physicist - I would expect there to be more "caveats" included by a serious scientist. I suppose it could also be the editing of Spadout to remove what they deem to be unneeded complications.


altelis


Nov 21, 2008, 11:57 AM
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rockforlife wrote:
In reply to:
The weight (15 oz of steel)

Wow thats it, just seems like that wouldn't give you the best test results. But it was a constant so i guess that works.


if it were 15 oz's of pancakes, OTH, that would make a huge difference!


mheyman


Nov 21, 2008, 1:57 PM
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About 6 years ago I had limited access to some very very sophisticated lab equipment that I helped design. I tried several tests and learned that really good test were going to require a good bit of trial and error to develop, time that I did not have. Simpler tests showed that while the rubber I tested (5.10, La Sportiva, Boreal ) was similar at reasonable temperatures, 5.10 rubber remained softer lower temperatures - say 0F or below.

Most everyone agrees that 5:10 rubber feel softer than the others and given time I think I could have developed tests useful in designing and choosing climbing shoes.


k.l.k


Nov 21, 2008, 2:27 PM
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Re: [Valarc] Shoe Rubber Testing [In reply to]
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Valarc wrote:
Arrogant_Bastard wrote:
Some obvious issues I saw was the light weight used. I’d guess this would significantly favor softer rubbers.

My thought was sort of the opposite - I was thinking a heavier weight might favor softer rubbers, since they are more prone to deform. I guess it depends on how soft "soft" is.

My other thought was that this isn't terribly applicable to climbing performance. Friction is, no matter what they taught you in high school, a lot more complicated than F = mu*N. In fact, that silly "independent of surface area" nonsense breaks down in all but the simplest cases, and even breaks down in those simplest cases sometimes (I ran into this one a few years ago when I was TAing undergrad labs). So looking at the point where a chunk of rubber starts to slide on a smooth surface is, IMHO, not very useful. It's telling you nothing about how that rubber would stick to actual, featured rock.

In my limited personal experience, "softer" rubbers tend to be stickier from a smearing perspective, because they can deform more to the contours of the stone, putting more surface area in contact. The tests seem to show the exact opposite of my personal experience with Vibram vs. Stealth C4, where I found Vibram to be absolutely lousy at smearing compared to the Stealth.

I'm honestly a bit disappointed to see this study coming from a physicist - I would expect there to be more "caveats" included by a serious scientist. I suppose it could also be the editing of Spadout to remove what they deem to be unneeded complications.

This obviously isn't going to pass peer review at any academic journal. But this is pretty close to the tests that 5.10/Stealth used for years to test--and then to market--their rubber.

Actual tests while wearing climbing shoes are even less useful, because of the variation in shoes. And that probably explains the wide variation in anecdotal accounts of which rubber smears best. My kletters and my Moccasyms have identical rubber. But one pair smears way better than the other.

I no longer care all that much-- although it takes awhile for me to adapt when I do change out rubber-- took me weeks to get used to the Acopa rubber.


dlintz


Nov 21, 2008, 2:47 PM
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Arrogant_Bastard wrote:
I know that shoe rubber is hardly a safety issue, but people seem so bent on their preferred shoe, dismissing all others, that I thought I’d post this up for some scientific critique. I came across this page on testing Spadout did on rubber from various shoe companies. Hardly extensive or well-rounded, it mainly comprised of comparing the static coefficient of friction for various rubbers. Typical weight on rubber on inclined plane deal.

http://www.spadout.com/r/climbing-rubber-test/

Some obvious issues I saw was the light weight used. I’d guess this would significantly favor softer rubbers. The temperature was held constant, and I know companies target an optimal temp, which could be different from company to company. There was also a minimum of different surfaces and contours tested.

Additionally, this doesn’t even touch on shoes, simply the rubber. It just caught my eye because I hear so much negative talk about Evolv rubber from 5.10 die hards, and here they are as the ‘stickiest’ in this particular test.

I'm not reading that.

d.


Partner cracklover


Nov 21, 2008, 3:34 PM
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15 lbs over four square inches of rubber is a joke. I'm sorry, but it sounds like they did a lot of nice work to prove something entirely irrelevant of any real world situation.

Even discounting the issues of irregularities in the rock...

Difficult slab problem: You're getting a little help from your hands, but the key issue is to be able to lift one foot to place it onto a higher dish or crystal without the other one blowing. Weight per square inch, probably in the range of 20-50 lbs, not 4.

Difficult technical face: Driving hard on a tiny surface area. Weight per square inch probably in the range of 30-60 lbs. Maybe more.

The only thing I can think of that this test applies to is on steep face moves where you have all your weight on your hands and are desperately counting on tiny friction from one foot to keep you from barndooring.

GO


curt


Nov 21, 2008, 4:02 PM
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The problem is that this test (a simple coefficient of static friction measure) doesn't replicate what happens when climbing shoe rubber comes into contact with normal rock--be it granite, sandstone, limestone or whatever. By definition, coefficients of static friction involve placing two completely flat surfaces against one another--and then increasing the angle of steepness until the top piece of material slides on the bottom piece. That is how this test was done, but in climbing we rely on the deformation of the low hysteresis rubber on our climbing shoes to "interlock" with the features on the non-smooth foothold surfaces. This test is not useful as a measure of that most important rubber property.

Back in the early days of Fires, I remember Bachar telling me how they sucked for climbing on glacier polish--well, this test is basically demonstrating how various climbing shoe rubbers perform on glacier polish, and nothing more.

Curt


k.l.k


Nov 21, 2008, 4:34 PM
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cracklover wrote:
The only thing I can think of that this test applies to is on steep face moves where you have all your weight on your hands and are desperately counting on tiny friction from one foot to keep you from barndooring.

As it so happens, that is precisely the move-- two of them, actually --i am working this week on the rare occasions i actually get to touch the rock.

Not that i can blame the rubber for my difficulties.


adatesman


Nov 21, 2008, 5:35 PM
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Partner j_ung


Nov 22, 2008, 6:25 AM
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Though I don't do it, I've known a couple folks who wire brush their shoes on a regular basis for, they claim, that exact reason.


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