Clipping into the thumb loop?

Sometimes when a cam is placed deeper in a crack clipping a draw into the nylon is really difficult, and ive found myself clipping an alpine draw into the thumb loop because it was easier to access.

BD doesnt use extendable slings on their cams because they feel it kinks the cable more than it should.

I was wondering if anyone has any information/first hand experience on the pros/cons of clipping draws into the thumbloops on cams. 

The sling acts as a flexible attachment point to your  cam and somewhat prevents it from walking. 

According to BD it reduces the strength of your cams by a few kn.  Don’t do it unless you have to.

I would skip doing that on smaller placements and sketchier gear, but I use WC for my larger size, and even if it does weaken a few KN....(I think WC quotes their cams as weakening 2kn when extended)... I can't see that being too big of a problem. Are people really out here taking 10kn whippers??

I think a bigger issue IMO is the higher possibility of a carabiner camming in the crack during a whipper and possibly breaking. That's just a theory though. 

Overall I have never done it, but I also wouldn't have thought twice about it if i had done it.... at least prior to this thread. Curious to see what comes out of this. 

He's not connecting a sling to the thumb loop in his  situation, he's connecting a biner. Everything that comes after the biner is immaterial to the connection to the cams thumb loop. I've seen no research suggesting that clipping a biner to the thumb loop is in anyway a safety issue (short of the obvious nonlocking aspect of biners used for alpine draws)

I’ve whipped on a BD C4 #0.3 I clipped through the thumb loop. The carabiner stripped some of the plastic sheathing off and bent the wire underneath, but the cam stayed put and came out normally when I pulled on the trigger. Ironically the only reason I had clipped the thumb loop rather than the sling was because I had wanted to roughly equalize two marginal placements (the other was a blue alien).

Generally speaking I have no problem clipping the thumb loop for a static load, like body weight while aiding or in an anchor, but I try to avoid clipping the thumb loop if I might dynamically load the cam.

Artem Vasilyev wrote:

Agreed, the thumb loop thing is not an actual safety issue - but it does technically reduce the kn of the cam according to BD QC labs (the cable fails on the pull test when you don't use a bd stitched sling - carabiner probably falls into that category) 

That being said, nobody generates the forces you need to bust through the cable in a normal lead fall (9-10 kn vs 14kn), not even close. Not even in factor one falls, according to tests by Petzl. But maybe you could manage it in a super fucked up factor two. But that would mean that you did this at the anchor, and OP is talking about pieces above that, so that can be ruled out.

So imo this isn't a safety issue on those grounds - but homie may end up kinking the cables on his cams if he whips, which would be annoying.

Also agreed on the biner camming/crossloading idea since it would not lie flush with the crack - but perpendicular. Also would have a higher chance of unclipping itself in a fall. And the piece would walk a tiny bit more. That's pretty much it I think. I think it would marginally increase the odds of something weird happening, which we all know, does happen every now and then. Personally, I wouldn't do it. But I am a paranoid climber and prefer to do things in a way that feels the best to me in the moment, which this probably wouldn't. I haven't really had issues with clipping the slings on my cams. This all assumes that I am not aiding - but freeing. I am okay with clipping into my thumb loops with my aiders or daisies.

What about smaller cams?  I could see 2kn making a big difference with microcams.  Unless you have doubts about a cam’s sling (why are you climbing with it then?) I can’t see many situations outside of aid where it would make sense to do this.

it will depend on failure mode. for example if you get at a 2kn reduction from 10kn to 8kn at the loop, but have a 4kn limit at the axle/wherever, the 2kn reduction isnt that important.

I’ve clipped into the thumb loop on rare occasions. Sometimes you just gotta make stuff work in the moment, even if it’s suboptimal.

Black Diamond says in the instructions that clipping the thumb loop reduces the strength by 2kN for C3s, X4s, Z4s, and previous generation C4s.
I don't see that warning anymore on the new C4 instructions.

Dave K wrote: 
At the time the thumb loop design came out, it was common belief that one of the reasons for it was to give the ability to clip in directly. I can't recall for sure if BD recommended it or advised against it, but it was generally accepted as "feature" of the new designs. I've clipped a sling or draw into it occasionally to manage length of extension.

One of the reasons for the thumb loop is for aid climbing, where it is beneficial to be able to clip your ladder as high as possible.  In this situation, you're only exposing the thumb loop to body weight or a good bounce test though, so no harm done.

When I then move my ladder off of that piece and clip the rope into it as fall protection, I would not clip into the thumb loop, but would use a carabiner via the attached nylon sling (or with further extension if needed)

I aid off of them that way to get a higher top step... Still dont clip them as protection like that though, never found a reason to do this free climbing though... I know this kid I call "Deep Crack" because he talks about the crack needing to be deep, if it's too shallow he can't jam it haha... (aka he can't crack climb but a diff topic). Just saying this as you could change your handle to "Deep Cam" ;) im just kidding of course

I’m late to the party on this, but I want to answer the why.

The slightly reduced rating for clipping a carabiner into the thumb loop is because of the reduced surface area when force is applied. The wide sling attached to the thumb loop increases surface area and distributes the load across more of the cable.

A carabiner decreases surface area, creating a sharper bend in the cable loop where force is applied, and the cable will begin to split at that fold under a lower force than if it was applied via the sling. This sharper bend is also what results in a kink under pre-failure loads.

Take-aways:

1. If there’s not a compelling safety reason to clip the thumb loop, clip the sling
2. In real-life fall scenarios, the thumb loop won’t fail with a carabiner clipped to it for BD sizes .3 to 7
3. To reduce the risk of a thumb loop kink, girth hitch an alpine draw to the thumb loop rather than attach a carabiner to it (the hitch reduces the runner’s strength by around 40%, but that’s still over 13kN strong)

"I had wanted to roughly equalize two marginal placements (the other was a blue alien)."

In this fall you mentioned, what happened with that blue alien placement?   

• Only time I’ve clipped the thumb loop is at horizontals above a ledge where the racking biner would cross load over the edge. Less than optimal pro is better than no pro. 

Evan Bosso wrote: Black Diamond says in the instructions that clipping the thumb loop reduces the strength by 2kN for C3s, X4s, Z4s, and previous generation C4s.
I don't see that warning anymore on the new C4 instructions.

thanks for posting that, definitely missed that diagram in the pamphlet 

Matthew Clausen wrote: I’m late to the party on this, but I want to answer the why.

The slightly reduced rating for clipping a carabiner into the thumb loop is because of the reduced surface area when force is applied. The wide sling attached to the thumb loop increases surface area and distributes the load across more of the cable.

A carabiner decreases surface area, creating a sharper bend in the cable loop where force is applied, and the cable will begin to split at that fold under a lower force than if it was applied via the sling. This sharper bend is also what results in a kink under pre-failure loads.

Take-aways:

1. If there’s not a compelling safety reason to clip the thumb loop, clip the sling
2. In real-life fall scenarios, the thumb loop won’t fail with a carabiner clipped to it for BD sizes .3 to 7
3. To reduce the risk of a thumb loop kink, girth hitch an alpine draw to the thumb loop rather than attach a carabiner to it (the hitch reduces the runner’s strength by around 40%, but that’s still over 13kN strong)

You beat me to it.  :-)

Alan L wrote: BD doesnt use extendable slings on their cams because they feel it kinks the cable more than it should.

If a single strand of an extendable sling will kink the cable more than the wider sling BD uses, a biner will kink it at least as much as the extended sling, so you are potentially going to damage the thumb loop.  Not enough to where it will fail under must falls, but it may put a kink in it.

If you know you are going to have to set it deep, can you clip and alpine or a sling before you set it?

Steve Levin wrote:

Interesting that the rope is back clipped in this diagram. 

Hey Steve:  It’s not back-clipped. The rope is coming from below and next to the rock, then going up through the biner and out to the leader’s harness — as it should. I agree that first attaching the biner to the sling would be better. 

George Bracksieck wrote:

Hey Steve:  It’s not back-clipped. The rope is coming from below and next to the rock, then going up through the biner and out to the leader’s harness — as it should. I agree that first attaching the biner to the sling would be better. 

seems like the thumb loop was clipped with the gate behind the loop, where it should be gate in front. as shown the biner wants to twist

C Limenski wrote:

seems like the thumb loop was clipped with the gate behind the loop, where it should be gate in front. as shown the biner wants to twist

I don’t like the biner in that pictured position. I just don’t think that it’s back-clipped.