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Academy: Understand the Physics of Friction to Climb Better

Part of our "Toes to Knows" Climbing Academy series--covering climbing from footwork to mental preparation.

Tags: Coaching, Handholds, Footwork, Intermediate


Knowing the physics of friction can help you climb better. Friction is a critical component of sticking to handholds or footholds. This is especially true when the holds are sloping. When holds are sloping or oddly shaped, you’ll stick to the hold a lot better if you can maintain your force “normal” to the hold.

What does “normal” mean? It means perpendicular or straight into the hold. I apologize for using a physics term on you, but I like physics so I’m going to use it!

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If you push, or pull, straight (i.e. normal) into the hold surface, you will maximize your chance of staying on the hold. If it’s a handhold you’re using, lean your body in a way that allows you to pull directly against the best part of the hold. If it’s a foothold, shift your hips, leg and foot position so you can maximize your normal force.

Here’s the physics equation that governs friction:

Friction = (Surface Roughness)  x  (Normal Force Into Surface)

We all know that rough surfaces have more friction than slippery surfaces. The equation also tells us that you can also increase friction by having more force on a hold, and maximizing the amount of that force that is normal to the hold surface.

Normal force sounds like an elementary topic, and in many ways it is. But building the habit to climb this way, recognizing how to use oddly placed footholds can be difficult. It can be especially challenging on steep routes when the hands and feet are at unusual angles. Reading dynamic moves so you can land them first time with maximized normal force can also be challenging. Great climbers intuit these body positions on the fly, maximizing their onsight potential.

Practice Drill:
During your warmup, experiment with sloping handholds and footholds. Grab a large pinch sidepull. Start by pulling directly “normal” (sidways) to the pinch, then slowly move your weight straight below the pinch. Compare how much harder it is to hold onto the pinch when you aren’t pulling normal to the surface.

Try a similar experiment with footholds. Start on a large sloper, matching the angle of the sloper and pressing straight into the hold. Then move your body until your foot slides off.

Climb some warmup boulders being mindful about how you are pulling and pushing on the holds. Are you in the right body position to maximize your friction potential?

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