Full crimp

Also called closed crimp, crimping, thumb lock, voll aufgestellt · Hands and holds

The middle joints bend past 90° and the end joints bend backwards. The thumb often locks over the index fingernail. It is the most secure grip on tiny edges, but it puts very high loads on the finger pulleys [161, 167, 171].

Grade From V5, holds get “smaller and crimpier” [170]. Some tiny edges then work only with a full crimp.

How to do it

Put your fingertips on the edge. Lift your knuckles until the middle joints bend past 90°. The end joints bend back.
Lock your thumb over the index fingernail [167, 171]. It adds force without loading the other fingers more [198].
Bring your palm close to the wall. It gets you further behind an incut edge [176].
Use it for the hard move only. Go back to a half crimp or open hand on the next hold.
Keep your feet solid. A foot slip jolts the fingers hard [162, 174].

Figure 65 Full crimp from the side, the thumb locked over the index fingernail. The middle joint bends past 90° and the end joint bends back. The load on the A2 pulley is particularly high.

Common mistakes

Full crimping holds big enough for a half crimp or open hand [171].
Making many hard crimp attempts in a row [172].

Tall climbers. Long fingers can make this grip feel unstable [167]. Keep it for single moves.

Related: Half crimp, Using the thumb, Open hand
Watch: Crimp Grips Tutorial: Crimp Like a Pro Climber (Adam Ondra); How to master the FULL CRIMP (Advanced Training for Climbing) (Alex Tighe)
Sources: [161, 162, 167, 170–172, 174, 176, 198]
Referenced from: Half crimp, Using the thumb, Latching, Progression map, V5 (Font 6C/6C+), Starting as an adult, Glossary of climbing jargon

Is the full crimp dangerous?

Your finger tendons run through pulleys. The A2 pulley sits at the base of the finger. A crimp bends the finger sharply, so the tendon pulls hard on it.

Pulley injuries are climbing’s most common overuse injury. A 2021 review names the crimp grip as the cause [199].

In one model, 96 N at the fingertip put about 255 N on the A2 pulley in a crimp. The open “slope” grip put about 8 N on it [174, 200].

Schweizer puts pulley forces in a crimp at 3–4 times the fingertip force. They become particularly high once the middle joint bends past about 80°, and he advises against bending it past 80–90° [161]. The half crimp in this book, at 85–90°, sits at the top of that range (this book’s reading).

A sudden jolt on one finger, as from a foot slip, can put about 450 N on A2. Its cited breaking force is about 400 N [162].

The model above compares a crimp, with the end joint bent back, with an open grip. We found no pulley load figure for the half crimp, measured or modelled, so the model can’t say whether a half crimp saves anything, or how much [200]. The research found for this book does not compare injury rates between full and half crimping.

Coaches disagree about what follows. A physio-based guide says use the full crimp only when needed [171]. Ned Feehally calls controlled full-crimp training on a fingerboard (a board of small edges to hang from) “relatively safe”, though “not 100 per cent risk free” [201]. Hooper’s Beta says pulleys get stronger with load [174] and links tears to a hand forced open under full load [172].

What to do (this book’s suggestion): use the half crimp or open hand by default. Keep the full crimp for the move that needs it. Warm up on 8–12 easy problems first [161]. A warm-up lets the pulleys stretch a little, which is thought to protect them [199].