Also, as an old trad dude who started by clipping pins, I almost always flip over the bolt end 'biner immediately after clipping. I do this before clipping the rope end. We used to do this to prevent exactly this issue--the 'biner getting hung up in the eye of a pin. I'm trying to quit; it really pisses off whoever gets to clean the draws but, old habits die hard.

The general take-home message for me is to:
-double-check your draws, to make sure they are hanging properly and not snagged or twisted
-avoid kicking or shifting your draws as you climb past them
-look down and double-check that you haven’t kicked them
-be mindful of the fact that you really aren’t out of the “danger zone” when sport climbing until you are fairly high up
-avoid falling when you have only one draw clipped.

The lack of a mark on the outside of the tip would suggest to me it may have been wrenched open in a fashion really close to your theorized pics, but with the tip not wrenching against the bolt head. The bolt has a point positioned where this would likely occur.

Petzl or a metalurgist can likely add much to your solving of the mystery "what done it". Is it practical, not really.

A little unanswered question in my mind, was the fall vertical? Or with some side or outward pull on the draw when the rope came taught? A little jump to make for a clean fall could have perhaps been part of the issues that may or may not have positioned the biner in the perfect wrong position?

Interesting post, and the answer may never be understood. But I can walk away with the reaffirmation that all climbing does have unforeseen risks. When you do everything right, shit can still happen.

Would this carbiner have been broken if you had climbed the route tomorrow?

I'm with csproul on this one.

Nice troll that sucked in a bunch of the normally wary old-timers. Goes to show it's not about the content, it's about the author.

Happy April Fool's and kudos on the effort that went into this.

The point highlighted in blue implies that the point highlighted in green should also apply to the second, third, and often the fourth bolt or even the fifth. However, adhering to such a rule would adversely affect one's performance as a sport climber, which suggests that we should look for other ways to prevent breaking carabiners. We should be careful about not shrugging off the orientation of the draw wrt to the direction of the climbing above it, or the orientation of the biners with respect to each other (the cis/trans debate). Perhaps, when hanging project draws, we should use locking biners on the bolt end or "clip and flip" the top biner.

[snip]

That's why I am thinking in terms of "yes, pay attention to it as much as possible, especially when you are working a route long-term, but you may not be able to prevent it from happening 100% of the time even so"

I am puzzled by the defensiveness I sense in the snipped material.

I think there are a few practical lessons we can learn from this event. We should learn to recognize situations in which our movements can affect the draw we're passing. and when we encounter those situations, we should protect against them (say, by flipping the top biner), or at least look down to make sure we haven't messed up the draw. At a minimum, we should realize that any time any part of our body hits a draw as we move past it, we should not blindly assume that the draw is just fine. When in doubt it might be better to "take" at the bolt and fix it rather than just climbing past it.

Lena,

When I look at how you show the draw hanging did you fall out and pendulum left and do the usual bit of twisting in the air?

If this was the top-most biner I could almost see the rope pulling a kink through into the biner and as Lena spun the kink torqued the draw around in the spin, snapped the biner and then unkinked.

If there was slack in the line and I know Lena climbs lead strong enough to want a soft catch that there would be. It's not inconceivable that a kink or twist may have for a moment formed as the rope pulled through (am I on glue?) and then as she fell and twisted with a big ol kink in there that the torque would have snapped that draw the moment the slack took and the entire system loaded. At best that biner would have what... 9KN of breaking strength at most. I'd venture even less if it was torque-loaded.

Anyway, just the thoughts of a person sitting a long, long, long, ways away.

Good luck on solving that puzzle.

Wow. Thats spooky stuff. Did you have to change pants before the redpoint burn?

I don't have anything to add on the prevention front, other than to mention that the biner might not have been able to bind against the rock in that way if the bolt had been a glue-in with a larger opening and rounded metal surfaces. I'm just talking out of my ass here but having seen how the top biner moves within certain glue-ins and settles back, I feel like the chances would have been less.

Edited to remove a reference to a specific bolt manufacturer. I won't associate their product with my speculations

But then I go back to that specific route, that specific move... and I can see only couple possibilities that do not involve placing a permadraw there, or screw-gate draws:
-- hang a trad draw on that bolt, instead of a regular sewn dogbone, because it would be less likely that nudging the rope-end biner (unavoidable in the move I do) will dislodge the bolt-side biner
-- don't climb that route again

You don't think that flipping the top biner over would have been effective?

Maybe it would have. But playing around after the fact, my partner was able to get the biner stuck on that bolt/rock, regardless of how it was flipped and which way the gate was facing.