[i.munro]

Quaine F, Vigouroux L, Paclet F, Colloud F. (2011) The thumb during the crimp grip. Int J Sports Med. 32(1):49-53. doi: 10.1055/s-0030-1267230. Epub 2010 Nov 17.

 This study analysed how the forces exerted by the fingers are modified by the additional action of the thumb. The results showed that the thumb increases the resultant forces exerted on the hold.


I can't be bothered copying and pasting any more.

Isn't that what I said above "5 > 3"  ? 

[TheTwig]

Must admit I'm somewhat suprised that this isn't more settled?

From what I've read/heard (or think i've read/heard!)

crimping is generally more secure/stronger grip (ignoring things like pockets, something blocking your knuckles, or where you physically don't have the reach to crimp a hold and are on by your fingertips etc)

- Thumb is stablizing fingers
- grip strength is increased at that (crimp) angle
- for small sharp holds you are actually increasing the surface area of skin on the hold
- for people with short pinky fingers it lets you get your pinky onto the hold

I used to crimp absolutely everything when I started and it was really holding me back. Spent a year specifically climbing everything open handed no matter how hard it made it, and now my open hand is actually stronger than the crimp grip (if I'm hanging on the same hold on the fingerboard). There are still fingertip things on slabs that I have to crimp no matter what, and then it seems more a function of getting more of your finger actually in contact with the hold

Just my 2p

[Muenchener]

I'm trying to teach myself crimping at the moment having been a natural open hander all my life. I can crimp a small campus rung for about half as long as I can open hand it.

Pretty much the only place I find myself naturally crimping is on slate, with those very small but slightly incut holds where getting some fingertip down inside the hold feels more secure.

[jwi]

All strong crimpers I know have long thumbs that they can wrap over more than half of the index finger.

What was the question again?

[shark]

I did mean a full crimp as you get the most "flex" with that

[spam]

I agree that  hyperextension going from 1/2 crimp to full crimp has a lot to do with levers, and also has a bit to do with skin contact on very small +ve crimps.  The change of angle means that the muscles that hold the middle PIP joint at 90 degrees aren't working as hard (the hold is applying force to this lever at an oblique angle=less force for this contraction)  This full crimp is also a great way to trash your fingers for the old, so perhaps the youth have another advantage (beyond their flexibility to hyperextend and generate a more oblique angle).

 I'm not sure I buy the "its just 5 > 3 argument", or "thumb stabilization" as always being the reasons to crimp.  Lots of hard bouldering is done with  thumbless crimps or 1/2-crimps.  This video is a beautiful compendium of thumbless crimp use https://vimeo.com/98228188#t=4:00

There are actually a couple of times in the video where different climbers have their thumbs wrapped on a crimp to set up on a hold, but then drop the thumb and retain the crimped or 1/2 crimped finger position (e.g. 4:36).  If crimping was all about thumb strength and stabilization they wouldn't be crimping on those holds still, would they?

[Sasquatch]

Hard to say everytime.  Using your thumb changes you wrist angle, and also allows for slightly different angle of pull.  i.e. it's much easier to chicken wing a full crimp than it is to chicken wing a 1/2 crimp.  There are times when chicken winging is good

I reckon it's important to be able to do both well.