Key takeaways
- A dihedral is an inside corner where two rock faces meet — an open-book 'V' shape.
- It's climbed from the inside using opposing pressure: stemming, laybacking, or jamming.
- It's the concave opposite of an arête (an outside corner or edge).
- Dihedrals reward body positioning and opposition over pulling on positive holds.
From the geometric term for two intersecting planes.
What a dihedral is
A dihedral is an inside corner in the rock, where two faces meet at an angle to form a ‘V’ or open-book shape. You climb it from inside the corner. Also called a corner or open book, it’s the concave opposite of an arête (an outside edge).
How to climb one
Dihedrals often lack positive holds, so you climb them with opposing pressure between the two walls:
- Stemming — pushing out against both walls with your feet (and sometimes hands).
- Laybacking — leaning off one side of a corner crack while your feet push the other.
- Crack jamming — if there’s a crack in the back of the corner.
In a smooth open-book corner with no holds, a climber stems — pressing one foot on each wall and pushing them apart — to stay in place, then laybacks up a crack in the back of the dihedral, using the two walls in opposition rather than pulling on any positive holds.
Dihedral vs arête
A dihedral is a concave inside corner climbed with opposition; an arête is a convex outside edge climbed by balancing and pinching. They demand opposite techniques — mastering both expands the terrain you can climb.
The bottom line
A dihedral is an inside corner — the open-book 'V' where two rock faces meet — climbed from the inside using opposing pressure rather than positive holds. Stemming, laybacking, and crack jamming are its tools, rewarding body position and opposition. It's the concave mirror of an arête, and learning to climb corners efficiently unlocks a whole category of routes.
Frequently asked questions
What is a dihedral in climbing?
A dihedral is an inside corner in the rock, where two faces meet at an angle to form a 'V' or open-book shape. You climb it from the inside of the corner. Dihedrals are common features and are also called corners or open books — the opposite of an arête, which is an outside corner or edge.
How do you climb a dihedral?
Dihedrals often lack positive holds, so you climb them with opposing pressure: stemming (pushing out against both walls with your feet and sometimes hands), laybacking (leaning off one side of a corner crack while feet push the other), or jamming a crack in the back of the corner. Body positioning and using the two walls in opposition matter more than pulling on holds.
What's the difference between a dihedral and an arête?
They're opposites. A dihedral is an inside corner — a concave 'V' you climb from inside, using the two walls in opposition. An arête is an outside corner or edge — a convex rib that juts outward, which you climb by balancing on and pinching the edge. Dihedrals and arêtes demand quite different techniques.
Sources
- Rock features & climbing — American Alpine Club
- Climbing technique — UIAA