/ Metolius Ultralight nuts
My question should of read, Is 7Kn a bit light on the strength side for breakage and longevity ?
I've been using them for just over 2 years now and I really like them. To answer your question about 7kN... I've taken lead falls on them a few times. Consider the highest force you're (hopefully n)ever going to put on a piece of gear... how about a factor 2 fall on a static sling? I've done that too (long story.. I retired the sling) and it held, no visible damage to wire, solder, nut, etc. So they can take big forces.
In terms of longevity, one of them has a pretty bent wire from one second's attempt at removal but that's almost* entirely cosmetic and can happen to any nuts. Then again, 2 years isn't that long to talk about climbing hardware...
As for other positives (I know, you didn't ask for this...), they seem way more stable in a sideways placement because of the more 'square' cross-section. And because they're not swaged you can rack the entire set on one krab without them getting messy and hard to take off.
Negatives... Everyone else uses rocks and walnuts so may not like leading on your rack. They don't fit as well into the slots that have been worn out by generations of rocks and walnuts!
*almost because in one situation it did make removal pretty tricky as you'd push it up and the bend in the wire would push it further back into the crack...
After taking falls, or over-enthusiastic nut removal, a (wall)nut often develops an s-bend making the position of the nut awkward for future placements. However, with nuts that have a loop of wire which goes over the nut and back through, this problem can usually be easily fixed by sliding the nut down and re-adjusting the position of the nut on the wire.
I believe Metolius nuts have cable stoppers. Does this affect the "re-usuability" of the nut?
I'm not sure I'm picturing exactly what you mean, but I think this is similar to what happened to the one I mention as having a bent wire. It's more like a kink both wires right at the head of the nut, not very sharp, but it won't bend back.
You're right that the wire is soldered (or otherwise fixed to the head of the nut) so there is no loop of wire, but I'm not sure this would help solve the problem in this case.
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