How do forces on slopers work?

Kyle, 

Focus the argument here on 3 things/contexts…

1. 1-4 fingers applied to the smooth flat wooden Beastmaker sloper of the OP

2. The boot to slab and/or climbing wall or sloper hold you mentioned/brought up and you posted videos about from your experts   

3. And your quote of…

“Everyone knows more shoe rubber on the rock produces more adhesion, even though Amonton’s law would say not.”  

My positions with respect to the above are;

1.  Application and direction of applied force is key.  Surface area of full fingers or just fingertips is irrelevant.  

2.  In terms of friction only, on a smooth rock slab, climbing hold, climbing wall, or concrete, asphalt, etc,  the surface area of your shoe on the surface doesn’t matter for any practical, measurable, or “climber meaningful” manner.   Say an average climbing shoe has approx 62 sq. Inches of rubber surface on the front portions, you will get the same “hold” on the wall or rock due to friction with 31 square inches of the same rubber and same normal force.  The hold force is 99.99% due to the angle of applied force (leg A in pic below, vs leg B) the shoe surface area is really just a correlation in this case, not a causation.

I am confident here because I have done the tests.  You can too.  

3.  As far as the quote goes, it is simply not true from a frictional analysis point of view.   Now some rocks (most rocks) are not uniformly smooth and have small edges and features, even slabs, and you can use these to maximize your “adhesion” in a general sense — meaning standing on them to stay on the climb, more akin to “edging”, but these are then mechanical supports and are in a different context of discussion vs purely frictional effects.

I totally understand the unique aspects of visco-elastic materials.  I play Broomball in the winter and if you’ve ever seen Broomball shoes, they try to use this to advantage on ice.   With limited success.  Climbing shoes simply aren’t as effective as you think.  There’s nothing magical about a friction coefficient of .8 -1.0 for most climbing shoes   

I’ll put my money where my mouth is (always do) for anyone interested to try, I’ll buy them a brand new pair of shoes if they can prove differently in a test (first person to post video results).  I’ve done the tests  

Edit:  I’d really like Kyle to post up what he thinks the results should be.  If so he’s sure, and I’m wrong,  then he should get on the record before he does a test and slinks away.   State your position.  Does double the climbing shoe surface on the wall, double the force?  Add 60%? 75%? What practical effect do you think it has?  

Test: Take the sole of a climbing shoe, and put one of your 80 lbs curling dumbbells on it in your driveway.  (Simulates one foot pressure of  a “std person” ) With a force gauge, measure the force needed to get it moving,  do 5 pulls to get an avg. then cut the sole in 1/2 and do 5 pulls.  You’ll get the same force.  You’ll get the same force (within a few ounces due to experimental tolerances) on a climbing wall or a smooth granite slab.  

As far as a climber is concerned with fingertip surface area or the front surface area of their climbing shoe, it doesn’t matter.  Amount of force directed where you want it (generally perpendicular to the surface at hand) matters

Just to wind this up and summarize the takeaways for anyone (class, anyone…anyone) who may be even remotely still interested at this point. 

As I stated before, I didn’t disagree with Kyle’s points per se, just that they are out of context and they just don’t apply to climbers in nearly all the typical climber scenarios and conditions and especially the scenarios presented in this thread….training boards, gyms, and most any outdoor routes.  

The hand is complicated, it has 5 articulable  “hydraulic arms” (fingers) that can direct forces independently and in a variety of directions.  It has different compliance and surfaces from tip to palm.  And it’s constantly changing/reacting to environmental stimulus.   But to maximize your finger grip on a training sloper, getting more finger surface area in an attempt to get more friction will do you no good.  Depending on the size and shape of the feature, in some cases getting a moister palm may increase your grip vs just dry chalky fingers not due to more surface area but due to the better coefficient of friction and better down force application on that part of your hand for that case.  

As for climbing shoes, unfortunately for the vast majority of climber weights and temperatures (say 40-90 F) we climb in, you get no noticeable benefit from added surface area of your shoes.   

An example would be 170 lb climber in Yosemite on an 80 F afternoon.  Whether they have 40 sq in of rubber to the rock, or 60, they get no detectable benefit - from friction alone- assuming they press the same either way.  

Now at extreme cases, very hot temps that greatly soften, nearly melt your shoes, and a heavy but fit climber who can put twice the pressure to the shoe, and a greater dwell time (moving very slow and stopping at each step) allows for the “fusion” so to speak of the rubber and rock) he may see a noticeable benefit of added surface area but not enough to warrant climbing slow on a hot day and being so heavy.  

It really is a simple test to do at home with any variety of materials, or old climbing shoes ideally.  Can even use a simple fishing scale if you don’t have fancy force gauges and you can prove to yourself that the Surface area (even double the surface area) doesn’t matter as far as your own climbing is concerned.   The very small “violations” of Amonton’s Law don’t really happen in your own typical climbing applications and even if they did, they’d be too small for you to notice. 

Contemplating potential applications of Kyle’s points though did make me think of trying my Broomball shoes on slab….could be interesting. 

I miss John

Mark Pilatewrote:

Edit:  I’d really like Kyle to post up what he thinks the results should be.  If so he’s sure, and I’m wrong,  then he should get on the record before he does a test and slinks away.   State your position.  Does double the climbing shoe surface on the wall, double the force?  Add 60%? 75%? What practical effect do you think it has?  

I'm just suggesting that we shouldn't discount area as a potential factor, until we have a good justification for doing so.  There is plenty of evidence that area is a relevant factor in similar scenarios (see previous links).  It seems bizarre to confidently claim it doesn't matter here, without anything to support it.

I would note that climbing performance is sensitive to much smaller changes than what you mention in your post.  Something as small as a 10% change in how hard you can pull could be several V grades or a full number grade (see all the data from Lattice).  As such, it might be hard to measure in your driveway with a fish scale.

 Kyle-  Fair enough.  I’ll admit that I cannot speak to any potential effects above 5.12.  And that any help whatsoever, even fractions of an ounce, at high grades may be vitally important,  But I’m confident that any potential effects you could measure will be well below the 10% level.  Probably in the low single digits (if any) with respect to hands and climbing shoes.  

In the past, I have only measured effects on  “typical climbing”—  fingers on Nicros holds and a variety of rocks, and several sets of climbing shoes on a variety of cements and concretes.

Ironically the reason for my first tests was when I was a relatively new climber and engineering student and was interning at Lawrence Berkeley National Laboratory, I also couldn’t believe that SA had no effect.  It was hard to wrap my mind around.  But using available test equipment at the lab, I proved to myself it was true.  Same results no matter how many fingers or how much rubber of shoe.   Then, when this discussion came up, I very quickly repeated the tests (not as rigorously) I did many years ago to re-validate my original findings using the 20, 60, & 100lb force gauges I have at home to test the friction effects of fingers on wood pieces and climbing shoes, weather stripping, and bicycle tire rubber on my cement front steps.  Same results.  No detectable difference between surface area “A” and “2x A”.     That’s also why I think that adding just a bit more more shoe or skin (realistically in the 10-25% range) would essentially be an infinitesimal benefit.  

I dont doubt that there is a potential at some level and in some conditions, Amonton’s law violations may become meaningful for some climbers at the highest ends.  I’d be interested in such tests and investigations-  as Curt84iroc pointed out -  it’s for sure nerdy, but interesting to me.   

frictional force is perpendicular to the surface. try to get your body weight under the best part of the sloper surface.

Mark Pilatewrote:

Many don’t understand that chalk is detrimental in many applications.   

Where can I learn about this? 

Adam Rwrote:

Where can I learn about this? 

There have been many studies of dubious methodology (and several contradict each other) and many magazine articles written over the years.   It’s a tricky subject with many variables and axes.   

Bottom line is that too many climbers, especially new gym climbers, apply a “monkey see, monkey do” approach and erroneously think “the more chalk the better”.    

So there is no question that chalk has its place and is beneficial to climbing higher grades in most conditions when used judiciously.  However, it is also a fact that in some conditions (lower temps, dry skin states, in situ residual chalk loading, etc) that reflexively applying more chalk to your hands is reducing your coefficient of friction, not helping it.  

Basically if the climb is below 5.10b and you’re not sweating like a pig, you just don’t need chalk.  

Two of its greatest benefits are the placebo effect (people think it helps, and so it does kinda) and the pacing, micro rest, and focusing aspect of stopping, taking a dip, and then moving.  

I’d wager a tidy sum that most people would climb better with about a 60% chalk reduction 

Mark Pilatewrote:

There have been many studies of dubious methodology (and several contradict each other) and many magazine articles written over the years.   It’s a tricky subject with many variables and axes.   

Bottom line is that too many climbers, especially new gym climbers, apply a “monkey see, monkey do” approach and erroneously think “the more chalk the better”.    

So there is no question that chalk has its place and is beneficial to climbing higher grades in most conditions when used judiciously.  However, it is also a fact that in some conditions (lower temps, dry skin states, in situ residual chalk loading, etc) that reflexively applying more chalk to your hands is reducing your coefficient of friction, not helping it.  

Basically if the climb is below 5.10b and you’re not sweating like a pig, you just don’t need chalk.  

Two of its greatest benefits are the placebo effect (people think it helps, and so it does kinda) and the pacing, micro rest, and focusing aspect of stopping, taking a dip, and then moving.  

I’d wager a tidy sum that most people would climb better with about a 60% chalk reduction 

The dude asked where he could find more information about how chalk lowers the friction and/or is detrimental to climbing and this is the response he gets   fuckin’ classic 

Go Back to Super Topowrote:

The dude asked where he could find more information about how chalk lowers the friction and/or is detrimental to climbing and this is the response he gets   fuckin’ classic 

Curious what YOU’d want/need?    It’s called google.  Type it in.  Or “Climbing” (magazine) or articles linked already in this thread.  

And I highly encourage everyone to do your own research and not just do what everyone else does.  

Or even ask Friction Labs (although I doubt they come out and say to use less!) — buy more and save

https://www.climbing.com/skills/science-friction-the-truth-behind-perfect-climbing-conditions/

Or look into the gymnastic roots of chalk use and it’s transfer to climbing.  Gymnastics selected it because It’s about moisture control and in some cases, reducing friction.  “Optimizing” grip for what they had to do.  It seems the majority of Climbers just assume it makes grip better no matter what.  

Mark Pilatewrote:

Curious what YOU’d want/need?    It’s called google.  Type it in.  Or “Climbing” (magazine) or articles linked already in this thread.  

I have no horse in this race, it’s just comical that the dude asked you for some info on how chalk can be detrimental to climbing (based on your initial post) and you proceeded to contradict yourself by saying it is, except when it isn’t all while providing him with no actual info he asked for. Seems like the typical answer on MP when people ask for information. 

And I highly encourage everyone to do your own research and not just do what everyone else does.  

I agree, however if someone asks me for information it could be helpful to provide the data and resources that you obtained the data from…not just explain your observations of gumby climbers and say how you think chalk should be used. 

https://www.climbing.com/skills/science-friction-the-truth-behind-perfect-climbing-conditions/

This single link is all the lad was asking for….could saved us both all this typin’

Or look into the gymnastic roots of chalk use and it’s transfer to climbing. It’s about moisture control and in some cases, reducing friction. 

Hoping his is a typo as typically climbers want to increase friction, not decrease it. With that said, moisture control and increasing friction often go hand in hand when speaking about climbing. Though I would like to know if any studies have been done regarding the coefficient of friction and its relation to humidity/moisture levels in the surface being tested. A link to a study of that magnitude would actually be beneficial to this discussion, as opposed to comparing the origins of chalk use in climbing 

Go Back to Super Topowrote:

I have no horse in this race, it’s just comical that the dude asked you for some info on how chalk can be detrimental to climbing (based on your initial post) and you proceeded to contradict yourself by saying it is, except when it isn’t all while providing him with no actual info he asked for. Seems like the typical answer on MP when people ask for information. 

I think I’ve been consistent in this and other similar threads over the years.  I’ve never said “chalk was detrimental to climbing”  as in a blanket statement.  I said it CAN be in many applications and when overused.  I proceeded to clarify, not contradict 

I agree, however if someone asks me for information it could be helpful to provide the data and resources that you obtained the data from…not just explain your observations of gumby climbers and say how you think chalk should be used. 

it’s not always so easy to just dredge up 30 years of study and testing in a link.  Despite what it seems, I actually have work to do, lol  

This single link is all the lad was asking for….could saved us both all this typin’

I just went out and found it and grabbed it after your post as an example.  Usually I leave it to the reader.   I already did the studying (and original research/testing) I don’t want to do more work.  In a sense, this is better anyway.  Id only post shit that agrees with my position…and it may not be current.   If people go out and find it independently, there may be new stuff available that either contradicts or expands upon my post/position.   Then we all learn something new.   I’m not afraid to be wrong.  I just rarely am  ;)

Hoping his is a typo as typically climbers want to increase friction, not decrease it. With that said, moisture control and increasing friction often go hand in hand when speaking about climbing.

Exactly.  It’s not a typo. That’s why I say “it’s complicated”   Chalk in Gymnastics is about OPTIMIZING grip -reducing moisture and providing just a bit of reduced friction to rotate around bars and such without grabbing and tearing skin.  Talc could reduce moisture but it’s TOO slippery and you’d fly off .   If they just wanted enhanced grip, they’d use rosin like baseball players.  Why don’t baseball players use chalk?

My point is that chalk allows you to optimize grip in some situations for climbing.  But it’s not just some magic friction enhancer that should be used universally all the time in huge quantities.  It can work against you sometimes 

There are studies that measured temp and humidity effects of various surfaces, with respect to human grip, but I believe they showed no meaningful correlations.  Some of these studies have what I’d consider some flawed methodologies and controls though, so take with a grain of salt. 

Edit to Super Topo below:   You’re misunderstanding my point.  Baseball players use sticky stuff, not chalk, cuz they just want GRIP.   My whole point has been that chalk is not the ideal grip  enhancer that many think it is  

I agree that climbers DO NOT want to reduce friction.   That is why they need to use chalk to appropriately manage moisture, greasy fingers, etc but in cool dry conditions for example, just adding more chalk inappropriately to already dry fingers, or already chalked up holds,  is more likely to reduce your friction and grip than enhance it, and thus I’m saying don’t do that.

The reference to gymnastics is to bolster the point why/how chalk can reduce friction.  Climbers cannot blindly adapt chalk use without understanding the full story.  Talcum powder is Magnesium silicate.  Very slippery and used as a friction reducer.  Chalk is magnesium carbonate many similarities, but importance chem structural differences.  It’s WAY less slippery than talc, and it has similar drying properties (why it’s used)  but it’s not some Friction enhancer fundamentally, just less  of a friction reducer than silicate. 

Mark Pilatewrote: it’s not always so easy to just dredge up 30 years of study and testing in a link.  Despite what it seems, I actually have work to do, lol  

Yet you managed to produce a link in reply to my post within the hour. Color me impressed. 

I just went out and found it and grabbed it after your post as an example.  

and it only took you one additional post to produce what was originally asked, congrats professor. 

Exactly.  It’s not a typo. That’s why I say “it’s complicated”   Chalk in Gymnastics is about OPTIMIZING grip -reducing moisture and providing just a bit of reduced friction to rotate around bars and such without grabbing and tearing skin.  Talc could reduce moisture but it’s TOO slippery and you’d fly off .   If they just wanted enhanced grip, they’d use rosin like baseball players.  Why don’t baseball players use chalk?

You are aware many pitchers also (attempt to) use sticky substances right? In fact using the sticky stuff is actually considered cheating because it helps so much in many situations lol 

Additionally, provide me with a single example of where a climber, applying chalk, would wish to obtain LESS friction. We are talking about climbing, I understand a gymnast would want to slide (for lack of better words) around the bar, but I can’t think of any situations where a climber applying chalk would wish to reduce friction…which is what you are implying in your previous post by comparing gymnasts to climbers.  Reducing friction certainly could be a goal when speaking about gymnastics and primarily gripping wood surfaces, but I fail to think of how reducing friction could be applied to a climber on rock…prove me wrong. I like learning. 

Go Back to Super Topowrote:

Not sure how to make my point more clear (that you’re missing …and perhaps others).  We are in agreement.   You’re practically restating my points above.   See my edit to you above in my previous post.   Here it is in a nutshell:

Climbers want friction. Chalk doesn’t always provide better friction in all cases.  

We should likely follow the baseball model rather than gymnastics. I cite those merely as examples of the disconnect in some prevalent climbing logic.

Just picking up on the shoe rubber thing. I'm sure several people will have dragged shoes or bits of shoe around under weight, and seen that area seems to not matter when it comes to shoe and stone or plastic. Maybe it's there, but it is small. 

What is there and big is force and direction. 

I can't really imagine a case with a shoe where one could increase area and not change force or direction. On a sloper, maximising area makes the force in the right direction. But it is the direction that matters.

Unfortunately the common belief that area is key can lead to people maximising area, at the expense of force or direction. Because it is hard not to, as the best direction is unlikely to maximise area, except on a sloper, which is I guess why the correlation in people's heads.

I only climb low grades, but my local crag is glass. Place a foot to maximise area and you are lost. Place to get as close to the normal as possible. People often don't even want to climb at this crag, because they don't get the force and direction thing.

I once had a lesson from Johnny Dawes, and he made the same point. Hence as an unbeliever like Mark I went out and measured it.

So, in the case where one can increase area without even slightly reducing force or compromising direction even slightly maybe it is useful, but I not sure that would be common. 

Go Back to Super Topowrote:

Yet you managed to produce a link in reply to my post within the hour. Color me impressed. 

and it only took you one additional post to produce what was originally asked, congrats professor. 

You are aware many pitchers also (attempt to) use sticky substances right? In fact using the sticky stuff is actually considered cheating because it helps so much in many situations lol 

Additionally, provide me with a single example of where a climber, applying chalk, would wish to obtain LESS friction. We are talking about climbing, I understand a gymnast would want to slide (for lack of better words) around the bar, but I can’t think of any situations where a climber applying chalk would wish to reduce friction…which is what you are implying in your previous post by comparing gymnasts to climbers.  Reducing friction certainly could be a goal when speaking about gymnastics and primarily gripping wood surfaces, but I fail to think of how reducing friction could be applied to a climber on rock…prove me wrong. I like learning. 

Fuckin classic. 

WF WF51wrote:

Fuckin classic. 

Lol.  Only the first two paragraphs.  The last 3/4 of the post was confused “argument” apropos of nothing.  

Which ironically is also perfect for this thread

Which boils down to: surface area doesn’t matter and most climbers are chalk stupid

Mark Pilatewrote:

Lol.  Only the first two paragraphs.  The last 3/4 of the post was confused “argument” apropos of nothing.  

Which ironically is also perfect for this thread

Which boils down to: surface area doesn’t matter and most climbers are chalk stupid

Mark - 0

Go Back to Supertopo - 1

For what it’s worth though, I feel like that was a jab at my initial post and not any shade thrown at you…but when you have an ego such as yourself I can why you interpreted that post that way. 

Well now GB Super T,  who’s really keepin score?! Lol.   Never can be too sure of what the hell is in the mind (if anything) of ol’ WF WF51.  You may be right.   But I was giving you props for your comebacks regardless.  

Edit:  I read your score as negative 1. 

I didn’t read this thread, I plan to later, so I’m not sure if this has been mentioned, but I’ve recently become fairly certain that there is also some unaccountable genetic component(other than hand size) which makes hanging the 45s significantly easier for some people over others. My only proof of this is that I’ve been climbing for 13 years or so and have trained extensively on the beastmaker. I can hang the 2-finger sloper pockets for about 10 seconds, I can do reps on the shallow one finger monos. I can hang one handed with both hands and crank pullups on the 35s. I cannot for even a second, pretend that I can hold the 45s, crimping or not. Which seems to make no sense. One of my regular climbing partners, can hang the BM 45s for a few seconds off the couch, but can’t do any of the other benchmarks I mentioned above. One day he brings his brother to the gym, who is not a climber at all, he was there on a day pass in rental shoes, and he ALSO hung the 45s for a few seconds. It’s notable to say my partner has pretty large hands and his brother has fairly small hands.