How do forces on slopers work?

In short, how can one climber hold a sloper, and another can't? Where are they generating extra force?

Let's say a climber, call him Emil, can hold a one arm on the beastmaker 45 degree sloper. Let's say another climber, call him Alex, can't do that. 

In terms of the forces, you have a weight force pulling down, a normal force from the hangboard pushing up, a portion of the weight force pulling you parallel and across the sloper, and friction force pulling up and parallel the sloper. In my way of thinking, the only force he can contribute is friction. If his whole hand is already on the sloper, how does he generate more friction than Alex?

More pulling (via wrist, lats, etc) equals more “weight force” returning more normal force, increasing the friction force and viola: dat boi sticks. Emil just pulls harder than you dude

The way I see it in your example is that the force pushing down (weight of climber) has to match force going up (strength of climber pulling down on the hold, which holds the climber “up“). This is assuming you’re bodies are both hanging down at the same angle and friction is close to the same. Emil matches that force and is able to hang, you do not. Now as far as your question in regards to how to get better/stronger at slopers. Much of this comes from wrist strength and stability, finger strength, as well as engaging your lats and abs in my experience.

In actual climbing however there are many more factors such as angle of your body, tension in the mid-section and lower body, wrist strength and mobility, core strength, friction, etc. 

Adam bloc wrote:

More pulling (via wrist, lats, etc) equals more “weight force” returning more normal force, increasing the friction force and viola: dat boi sticks. Emil just pulls harder than you dude

I think OP is assuming equal strength but maybe there is a technique aspect to be known for applying it to slopers more effectively

Sometimes I think the technique police are annoying but slopers are the most important holds to be sucked into the wall on. Just try to stay low and into the wall. 

Slopers require wrist flexion, and increased compression forces via shoulder flexion. As opposed to a crimp, where you can get away with only using finger strength. 

Wrist and shoulder flexion are applicable to all climbing, and are more critical with slopers.

Adam bloc wrote:

More pulling (via wrist, lats, etc) equals more “weight force” returning more normal force, increasing the friction force and viola: dat boi sticks. Emil just pulls harder than you dude

This is what I don't understand. How can you increase your weight force? Alex only weighs so much. Hes not pulling against anything, he's already off the ground. In a static hold, there's no acceleration to add extra force.

Increasing friction by "squeezing" the sloper? And engaging other muscles to stay under the hold.

I don't assume equal strength. 

Shoe Enthusiast wrote:

This is what I don't understand. How can you increase your weight force? Alex only weighs so much. Hes not pulling against anything, he's already off the ground. In a static hold, there's no acceleration to add extra force.

He can still be applying more force. I think isometrics would be great example of varying forces on a static hold. This is also why if you were to remove weight you would likely be able to do with Emil is doing. The amount of force he’s creating is more than what you can produce proportional to each other‘s weight. 

Not Not MP Admin wrote:

He can still be applying more force. I think isometrics would be great example of varying forces on a static hold. This is also why if you were to remove weight you would likely be able to do with Emil is doing. The amount of force he’s creating is more than what you can produce proportional to each other‘s weight. 

You can only apply so much force in a static hang before you create upward movement though. Do you mean his application of strength is more focused on angular rigidity in the wrist or other area better than Alex? This would make sense to my brain as I am assuming equal skin conditions and friction coefficient between skin/wood. Even taking weight off, I can’t hang on BM 2000 45° slopers most the time unless I pinch the underside with my thimbs, increasing the frictional force on the sloping portion of the hold

Friction is created by force applied normal to the surface. Gravity is always pulling straight down but you can redirect force through your wrists and fingers into the sloper. In terms of the friction at the surface there is variability and the net force applied will be reflected by the secondary  force you supply through your fingers, wrists, shoulders and body position. This direction IS variable and tiny changes in direction and magnitude will adjust the net friction force. As you adjust the angle you are pulling into a sloper you can feel the force/stickiness vary. Probably better to experiment off a super slick beastmaker, but the principle is the same. Bust out that free body diagram son!

John Clark wrote:

You can only apply so much force in a static hang before you create upward movement though. Do you mean his application of strength is more focused on angular rigidity in the wrist or other area better than Alex? This would make sense to my brain as I am assuming equal skin conditions and friction coefficient between skin/wood. Even taking weight off, I can’t hang on BM 2000 45° slopers most the time unless I pinch the underside with my thimbs, increasing the frictional force on the sloping portion of the hold

I guess what I‘m trying to say (poorly) is that the force Emil is applying is equal to 100% of his weight while Alex is not. Assuming they are different weights, Emil is applying more force proportional to his weight.

Not Not MP Admin wrote:

I guess what I‘m trying to say (poorly) is that the force Emil is applying is equal to 100% of his weight while Alex is not. Assuming they are different weights, Emil is applying more force proportional to his weight.

So is it maybe a matter of even distribution of force through the contact area? Is alex trying to crimp the sloper and reducing his effective contact zone?

Unless he’s pinching the sides of the sloper…but if we’re talking just the top of a sloper for two equally weighted climbers doing a static one arm hang, then only variable (assuming their hands have the same coefficient of friction) is the angle and specific point of force application.  

If he’s also a pitcher, check under his cap and pockets for a hidden rosin bag

You have to rigidly hold your hand in the shape that matches the sloper. It’s not just a matter of shear friction, like sliding your hand along a flat wall. You have to flex your fingers enough to counteract your weight exactly, so that your hand does not change shape at all as your weight comes onto it. 

It’s not like a 90 degree edge crimp where you’ll stay up with a variety hand shapes as long as your fingers don’t uncurl. If the sloper is 45 degrees, and you grab it and then let your hand flex open even a few degrees, you’ll slide off.

The requirement to rigidly hold some intermediate angle of finger flex is why stronger fingers help people hold slopers better. There’s undoubtedly a “feel” and technique factor as well. 

Seems like we’re all saying the same thing for once 

Don't overlook hand size and finger/palm width/breadth.  These also play a part along with core strength, etc.

I wonder if you took a picture from the side, if Emil's hips would be a few inches forward of Alex's. Maybe Emil is using his shoulder strength and flexibility, along with his core, to hold his body a bit more under the hold, creating a more advantageous angle for his hands. 

Also make sure Emil's not cheating with his thumbs.

Let's not get confused with real slopers on a climb, and the Beastmaker slopers, which are a party trick that rely on the unintuitive friction properties of wood.

Any amount of front-levering will not help on the Beastmaker, if you are statically free hanging, your center of gravity is always directly under the hold. Friction is 100% the limiting factor.

For rock you might focus on conforming your fingers to the hold to maximise surface area and thus friction. On the Beastmaker wood this isn't usually sufficient. The "trick" is that the friction with the wood increaes with pressure. So to maximise the pressure, you have to apply the same force to a smaller area. (And additionally, as most people with a wooden hangboard know, super dry skin and excess chalk or drying also hurts more than it helps, damp skin can actually stick better)

tl;dr The trick is you actually need to half-crimp the Beastmaker slopers to maximise pressure through your fingertips.

+1 to crimping the beastmaker 45’s. I can barely hang on them using normal sloper technique but if i chisel crimp them i can hang much more easily

Shoe Enthusiast wrote:

In short, how can one climber hold a sloper, and another can't? Where are they generating extra force?

Let's say a climber, call him Emil, can hold a one arm on the beastmaker 45 degree sloper. Let's say another climber, call him Alex, can't do that. 

In terms of the forces, you have a weight force pulling down, a normal force from the hangboard pushing up, a portion of the weight force pulling you parallel and across the sloper, and friction force pulling up and parallel the sloper. In my way of thinking, the only force he can contribute is friction. If his whole hand is already on the sloper, how does he generate more friction than Alex?

It’s quite elementary, climbers use leverage to increase friction.

So, if Yoda and Darth Sidious both applied the force to the sloper, which one has the most midichlorians ?