Climbers are taught to “pull straight down,” “use good body position,” or “trust friction.”
Mechanically, these are incomplete ideas.
The real rule is:
Friction depends on force direction relative to the surface — not on how hard you pull.
A hold generates usable friction only if your force vector aligns with its micro-geometry.
This single rule explains why:
- some holds feel terrible in one position and perfect in another
- small hip shifts double friction
- pulling harder often makes you slip faster
- slopers and sidepulls behave completely differently
- elite climbers seem to “create grip” out of nothing
This is directional friction — the foundation of real technique.
1. Friction Depends on Normal Force × Coefficient × Geometry
The friction equation is usually written as:
F_friction = μ × N
But in climbing, this is incomplete.
The real formula is:
F_friction = μ × N × cos(θ)
Where:
- μ = friction coefficient (rubber or skin vs. surface)
- N = normal force (pressure against the surface)
- θ = angle difference between your force vector and the ideal direction the hold “accepts”
If your vector is wrong:
- cos(θ) decreases
- friction drops
- the hold “loses grip”
- even strong climbers suddenly feel weak
Most slipping is directional, not strength-based.
2. Pulling Down Is Almost Never the Right Direction
Slopers want inward force.
Sidepulls want lateral force.
Undercuts want upward force.
Pinches want squeezing force perpendicular to the grip plane.
Incuts accept downward force because the geometry points up.
The ideal direction is:
perpendicular to the surface you’re touching
—not perpendicular to the wall.
This explains why:
- pulling down makes you slide off slopers
- sidepulls feel strongest when you twist toward them
- undercuts require hips low and outward
- pinches feel best when wrist rotation matches the grip plane
Pulling “down” is a climber myth.
Pulling correctly is physics.
3. Hips and CoM Change Force Direction More Than Arms
Changing your pulling direction with your arms is inefficient.
Your arms cannot reposition force direction without losing tension or leverage.
Your hips determine the global direction.
Examples:
- Move hips left → force vector rotates right
- Drop hips under a sloper → vector becomes more inward
- Rotate hips toward a sidepull → vector aligns with the plane
- Raise hips on an undercut → vector points upward
Elite climbers adjust hip position first, hand angle second.
Beginners do the opposite.
4. Wrist and Finger Angle Fine-Tune the Vector
Once the CoM and hips establish the primary direction, your hand adjusts the vector with:
- wrist flexion/extension
- wrist pronation/supination
- finger curvature
- DIP/PIP angle
- thumb engagement (on pinches, slopers, volumes)
Tiny changes in finger angle shift the vector by several degrees — enough to turn a bad hold good.
This is why elite climbers create friction where others cannot.
5. Directional Friction Explains Why Grip Strength Feels Inconsistent
You do not suddenly lose strength between moves.
Your friction changes.
Examples:
- You feel weak on edges when your hips drift out
- You “lose” slopers when feet cut and the vector collapses
- A crimp feels worse when your elbow flares out
- Pinches weaken when your wrist unintentionally rotates
- Gastons feel unstable when your CoM is too close or too far
The variability comes from directional friction —
not inconsistent strength.
6. Slopers Are the Purest Expression of Directional Friction
Slopers only work when:
- force is applied inward
- pressure increases surface area
- the CoM sits under the hold
- wrist angle maximizes contact
- hips reduce lateral torque
Downward pulling instantly destroys friction because cos(θ) ≈ 0.
This is why sloper technique improves radically with:
- hip drop
- wrist adjustment
- inward lean
- small rotational corrections
Slopers teach directional friction better than any other shape.
7. Harder Pulling Often Reduces Friction
When force direction is wrong, increasing force:
- increases tangential (sliding) force
- does not increase normal force
- lowers cos(θ)
- makes slipping more likely
- overgrips forearms without benefit
This is the physics behind “stop squeezing, use your body.”
More effort with wrong direction = faster failure.
8. The Rule: Align the Vector Before You Apply Force
Correct sequence:
- Establish CoM position
- Rotate hips to align the global vector
- Adjust wrist/finger angle
- Apply pressure
- Then pull
Most technique errors occur because force is applied before vector alignment.
Elite climbers never do this.
Their vectors are aligned before effort begins.