Tim White wrote:Scott McCrea wrote:[I tried this a few years ago. I was fully prepared to shatter a biner and crash to the padding on the floor. But, no matter what I tried (including bouncing and bouncing a two person load), I could not break one. Anyone else care to try?
Are you (and Anmar) saying that you tried to create the SAD effect and failed? If so, I want one of the biners you use, because they must be STRONG!
I've see the test and data that a leading equipment manufacturer conducted and my personal conclusion was that ALL carabiners will fail in this type of twisting cross-loading.
What I did was to take my rack, load it so that it was levered against the gate of the biner (locked) and bounce as
hard as I could against it (including jumping up as high as I could (15' rope in a tree) and coming down as hard as I
could on it. I couldn't break it. Granted, it was some skanky old SMC aluminum biner. I didn't try it with an 8
or other device, mine wasn't testing, just a demo to see what I could see.
Another aside, to add to my previous post: I also teach novices to check their connections before
committing to them. Not just a visual check, but a feel as well. It's so much of a habit for me that I
don't even realize I am doing it when I cave.
Andy: Where I do most of my caving, you do have to take your rappel device on an off rope a lot.
I've never felt that there was a significant increase in risk <for me>.