| Type | Crack-climbing jam |
| Crack size | Hand-width |
| Locks by | Expanding the hand |
| Difficulty | Intermediate |
A hand jam is the fundamental crack-climbing technique where you insert your hand into a hand-width crack and expand it — cupping the palm and flexing the thumb — so it locks against the crack walls. A solid hand jam is secure enough to hang and even rest on, and is the building block of crack climbing.
How to do it
Slide the hand in thumb-up, then expand by cupping the palm and pressing the thumb inward to lock against both walls.
Crack sizes
Hand jams suit hand-width cracks; narrower needs a finger lock, wider needs fist jams or offwidth technique. It’s the heart of jamming and crack climbing.
Skin
Tape gloves help protect the backs of the hands while learning.
Frequently asked questions
How do you hand jam?
Slide your hand into the crack thumb-up, then expand it by cupping the palm and pressing the thumb toward the fingers, which widens the hand and locks it against both walls. Done well, the jam is solid enough to hang your full weight on and even shake out the other arm.
Does hand jamming hurt?
It can scrape and bruise the backs of the hands, especially while learning, which is why many crack climbers wear tape gloves. A well-set hand jam shouldn't be painful to hold, but rough granite and repeated jamming take a toll on the skin.
What is a hand crack?
A hand crack is a crack roughly the width of a hand, where hand jams work — the most comfortable and secure size of crack to climb. Narrower cracks need finger locks, while wider ones require fist jams or offwidth technique.
Sources
- Crack climbing technique — American Alpine Club