Equalizing two pieces VS. clipping individually

Jake Jones wrote:

NRG is definitely waaaaay different than any western sandstone.  I've taken whips on a .2 X4 and a DMM Peenut with the full expectation that the pro would hold and it did.  

Out of curiosity, how does NRG sandstone compare to T-wall sandstone? T-wall sandstone is probably my favorite rock I've ever climbed on, it just feels so good. 

David Kerkeslager wrote:

 I've been looking at ball nuts lately (though I haven't bought any yet). It seems they can be difficult to clean after a fall, but they're rated for 8kN down into knifeblade-thickness cracks.

I would go with impossible to clean after a fall, although I can't say I've done more than body weight on one. The ramp section that the ball slides on is quite long, this severely limits their placement options. In granite at least I find they could work in about 25% or less of vertical seams, they just rarely are the same width long enough for the ramp to slot in and allow you to get them oriented for the direction of pull. In thin cracks at overlaps they seem to work more frequently (usually when the overlap is actually a large shield).

In addition to that when placing you have to locate the ball by holding your middle/index finger exactly in place, then allow the ramp to slide back out by moving your thumb backwards. It's very hard to do precisely one handed. Unless you're at a very solid and non tenuous stance I can't see ever placing one on lead free climbing, those stances seem to be rare on the routes you want gear that size.

Nick Drake wrote:

I would go with impossible to clean after a fall, although I can't say I've done more than body weight on one. The ramp section that the ball slides on is quite long, this severely limits their placement options. In granite at least I find they could work in about 25% or less of vertical seams, they just rarely are the same width long enough for the ramp to slot in and allow you to get them oriented for the direction of pull. In thin cracks at overlaps they seem to work more frequently (usually when the overlap is actually a large shield).

In addition to that when placing you have to locate the ball by holding your middle/index finger exactly in place, then allow the ramp to slide back out by moving your thumb backwards. It's very hard to do precisely one handed. Unless you're at a very solid and non tenuous stance I can't see ever placing one on lead free climbing, those stances seem to be rare on the routes you want gear that size.

In my experience they are harder than average to clean but not impossible, even after whipping on it. Perhaps as hard to clean as a nut that got whipped on a few times. But there is a steep learning curve for how to clean them.

I don't know what you're talking about with placing them, they place the same as a cam for the most part, although you need more precision than a cam may require to get a good placement. I've never had an issue placing them, even from a strenuous stance. I've never used them on granite, though, only sandstone.

Do you mean in terms of finding the placement they fit or actually placing the gear?

Granite is rarely truly parallel and your goal is setting is to get that "ball" above/on a constriction in the crack. Your muscle memory from placing cams is to let your index/middle finger move outward for the lobes to engage, that's opposite of what your hand needs to do when expanding a ball nut. My limited experience on sandstone has been that there are far more uniform cracks, so this might not be an issue you're seeing. 

Nick Drake wrote:

Do you mean in terms of finding the placement they fit or actually placing the gear?

Granite is rarely truly parallel and your goal is setting is to get that "ball" above/on a constriction in the crack. Your muscle memory from placing cams is to let your index/middle finger move outward for the lobes to engage, that's opposite of what your hand needs to do when expanding a ball nut. My limited experience on sandstone has been that there are far more uniform cracks, so this might not be an issue you're seeing. 

I usually try to find even a slight constriction if I can because they are more secure like that. When placing them,  I usually start a little bit above where I want the placement to go and then move it downwards while slowly releasing the trigger until I get it in the right spot where I'm getting a lot of surface contact on both the ball and the paddle. If I can get a whole lot of surface contact on both sides then I either place something else or look for a different spot.

Don't get my wrong, they aren't the kind of thing you can plug and chug like a larger cam, but they can be placed one handed with practice.

Yeah that's my method as well, I just find them more cumbersome. Although when it comes to placing a small C3 I don't find those easy/fast either when you make sure that you get the lobes equally retracted (it's easy to slam in a cam, it's harder to actually get it right). I find placing small wallnuts or brass offsets faster one handed personally. I'm climbing rock that always seems to have good constrictions though.

Nick Drake wrote:

Yeah that's my method as well, I just find them more cumbersome. Although when it comes to placing a small C3 I don't find those easy/fast either when you make sure that you get the lobes equally retracted (it's easy to slam in a cam, it's harder to actually get it right). 

I think this hits the nail on the head for me, although my takeaway is different from you I think. Yes, the ballnutz require a slightly different hand motion but I think that having to only make sure 2 moving parts are placed appropriately is easier than having to make sure 3 or 4 cam lobes are placed appropriately when the margin for error is very small like with a very small cam. So overall I find them about the same in terms of placing difficulty compared to a small cam.

FWIW, my interest in ball nuts started because I noticed a few previously-claimed-unprotectable overhanging Gunks climbs have been climbed with ball nuts as protection. So at least a few climbers can place them from overhanging stances.

Jake Jones wrote:

Don't know.  Never been to T-Wall.  I hear it's very similar though.

Ahh, I just figured that you would have, living so close. If you like roof cracks, you gotta go there some time, it's a mecca for roofcracks. Also has many spectacular aretes, as well as just being spectacular climbing in general. Only thing I could ask for would be more than 1 or 2 pitches long, but beggers can't be choosers.

David Kerkeslager wrote:

Patrik, is there any test data supporting this? I know this is true of master point anchors because longer strands will stretch leaving more load on the short ones since the "master point" can't move. In a sliding-X, if the longer strand stretches then the carabiner will just slide until the load redistributes... right? You could argue that friction between cord and biner throws this off a little, but sketching out a little free-body diagram has me convinced that it wouldn't be much.

I think the relevant measure is energy (absorbed by the rope), but I agree with the "not slowing your fall and contributing next to nothing to the piece below it that now must catch you by itself".  https://www.mountainproject.com/forum/topic/111226119/kn-and-micronuts references a study that found the rope springs back somewhat before hitting the next piece, but I suspect they tested pieces spaced farther apart.  If - as suggested earlier on this thread - the pieces are extended such that their biners attach to the rope at about the same level, I don't think the rope has time to spring back, and I would expect the 2nd piece to absorb almost no energy before popping (assuming the pieces are equally strong).  This makes me think extending the top piece to clip at the same level is actually detrimental.

The fact that equalization isn't perfect needs to be weighed against the fact that energy absorbed by a rope grows faster-than-linearly with force.  For an ideal spring, stretching the spring to 8kn absorbs 4 times more energy than stretching the spring to 4kn.  For real ropes, force grows faster than linearly with elongation, but not by a lot.  I would guess a real rope absorbs 3x more energy at 8kn than at 4kn.  Now we know 8kn is a dream - 5-6kn is more realistic for two equalized 4kn pieces.  So maybe the equalized 5-6kn anchor absorbs only 40-70% more energy than a single 4kn piece.  The question then is - has the rope, by the time it hits the bottom piece, shrunk by enough to now absorb 40-70% before reaching 4kn ?  It has to depend on the distance between the two pieces - the farther apart they are, the more likely separate attachments absorb more energy than an equalized anchror.  The break-even point between equalization and clipping separately, in terns of distance between the placements, must be at least of the same order of magnitude as the amount of rope stretch when the top piece blew - feet, not inches.

For me, it all depends on the the consequences of the pieces failing. The last in a long string of good pro with clean air? Clip 'em individually and charge. The only pro between me and eternity? Equalize 'em and channel Honnold until the next good gear. Or channel donahue and bail.