Crack Climbing
By Kiersten Johnson
Physics 212
04/2017
Hand Jams:
Hand jams are much like off-width body jams. A climber will slot their hand, thumb over palm, into a crack. They will slide the hand down until it is worked into a wedge. When the thumb is pointed towards the direction of gravity, a climber can hang off it and take a rest. Gravity allows the climber to take a rest. Gravity pulling the climber down forces their hand further into the constriction, and creates a good position for the climber to rest.
Steph Davis, crack climber, hanging from a thumbs down hand jam.
Photo from: http://stephdavis.co/blog/handjams-are-your-friends-crack-technique/
Foot Jams:
Smaller cracks are climbed more often. A crack climber uses torque to place their feet. The foot is placed into a crack, and then the knee is dropped produce torque. The torque allows the foot to rotate into the crack, and the rubber is pushed against the sides of the crack. The friction between the foot and the crack allows the climber to stand up onto their feet.
Diagram of feet placement and knee movement.
Photo from: http://www.climbing.com/skills/jam-session/
Off-width climbing is a form of crack climbing. In general, an off-width crack is defined as being too big for a fist jam, and too small for an entire body. Off-width climbing depends on gravity. In the image to the left, Pack is not holding onto anything with her hands. However, she is wedged at her hips into the crack, preventing her from falling headfirst out of the crack.
Pamela Shanti Pack, off-width climber, using gravity to climb Lucille 5.13a in Vedauwoo Wyoming
Photo from: https://s-media-cache-ak0.pinimg.com/564x/16/19/a5/1619a5501c7cd34bff554d067a3d1904.jpg
