I didn't say you *must* do this or *mustn't* do that. I said they weren't designed to do so.

My point is that when you put two ropes on the same piece, you're effectively doubling the diameter of the rope catching you

You agree that for non "joker" half ropes, a 40 percent increase of force is likely on that crux piece? f--- that! Look, do what you want, but when I get to a crux and I think I might fall, the *last* thing *I* want to do is to increase the impact force on my last piece by 40%!

If anything, we are cautioned against taking a high FF fall on a single strand of doubles. I'll have to go back and dig it up, but I do believe people have posted recorded incident in which a climber took a high FF fall on a set of doubles, but only one strand caught the fall, and that strand broke.

When I clip my doubles to a single piece there is always a reason...

Is the reason fear of one rope breaking under the force of a severe fall? Are there other reasons to clip both ropes together? If so, under what circumstances?

I would argue that a smart belayer would have you on belay on both ropes, but with more slack in one than in the other.

To divert the path of the ropes from areas of loose rock.

I found myself doing this recently, not with twins or doubles, but a single lead plus static trail line (belayed by only the single, of course). Same principle would apply to twins/doubles, I imagine. I didn't read much of the thread, exuse me if this is out of context.

With both ropes running through the same piece? ... Maybe if the ropes were clipped into separate biners, it might make sense to keep more slack in one rope than the other.

-Jay

A single thin line is more likely to be cut if sharp rock is present.

The only argument I've ever heard for consistently clipping both strands of a double rope system together early in a pitch was to avoid taking a high factor fall on to a single strand of rope that isn't designed to withstand it. In a perfect world, one strand of a double rope system would never catch the full force of a fall because the next lower piece (that would be close enough for you to fall past) would be involved in catching the fall (to some degree) and therefor the other rope would share the force of the fall (to some degree). I think that's the rational behind using 55 kg in the test instead of 80 kg.

Of course, that's a perfect world and doesn't account for run out climbing.

I often heard people state that they don't understand the use of twins. Personally, having used both twin and double systems extensively, I don't understand the use of double ropes. Dual purpose, twin/double systems probably make the most sense.

The attached link offers a good discussion on the subject http://groups.google.com/...8?hl=en&lr=&ie=UTF-8

If you could dig up any cautionary tales about the risks of taking hard falls on one double rope, or any advice from a respected source to clip both doubles together, I would appreciate it. The rationale for clipping both ropes into a single piece is not at all clear to me.

Is the reason fear of one rope breaking under the force of a severe fall? Are there other reasons to clip both ropes together? If so, under what circumstances?

Note that manufacturers do not recommend using a single half rope. The reason is that, tested singly with 80 kg, half ropes do not (as yet) pass the UIAA drop test. They do not, as far as I know, ever break on the first drop, but they cannot reliably sustain five fall factor 1.78 falls.

Fantastic series of posts, by the way.

This is interesting. How did you arrive at this conclusion?

Take a chill pill and relax a bit, don't get so worked up about this. I do not advice clipping both doubles to a single piece protecting a crux, that would be unwise.

You may have gotten this impression when I posted earlier that I like to place two pieces evenly with each other before a crux, and clip each of my doubles to each piece separately. This let the two pieces share the load if I fall, so the impact force on each piece is in fact lowered.

My earlier concern was not the impact force on the gear. My concerned was that in this practice, the climber experiences roughly the same impact force as if the doubles are clipped to the same piece. And if brutusofwyde is right when he said the impact force is greater than 12kN in this case, I may very well be doing damage to my own body in a big fall.

I'll have to go back and dig it up, but I do believe people have posted recorded incident in which a climber took a high FF fall on a set of doubles, but only one strand caught the fall, and that strand broke. [edited because I could not found this accident report, it might be a figment of my imagination] That's why I do not like the UIAA's test with doubles. Testing them with a 55kg weight is unrealistic at best, misleading at worst.

But, it is necessary to add eight(!) rope failures more in the time since 1983 amongst German and Austrian mountaineers and climbers. The causes were either a misuse of the rope or the rope was already damaged by some kind of polyamide contaminant, such as acid. The details are as follows.

The misuse was using a half rope or a twin rope in a single strand. This happened five times out of nine times altogether. The reason why they are not recorded in the table is because it is a misuse. Such misuse happened in 1973 on the "Schreckhorn" in Switzerland, in 1981 on the "Olperer" in Austria, and in 1990 on the "Grossglockner", also in Austria (all three climbers were killed), and two rope failures in the last year (2001), one when toprope climbing (bottom lowering), the other during abseiling by a mountain rescue team of two persons and a stretcher a few meters above bottom level (all three survived).

The only argument I've ever heard for consistently clipping both strands of a double rope system together early in a pitch was to avoid taking a high factor fall on to a single strand of rope that isn't designed to withstand it. In a perfect world, one strand of a double rope system would never catch the full force of a fall because the next lower piece (that would be close enough for you to fall past) would be involved in catching the fall (to some degree) and therefor the other rope would share the force of the fall (to some degree).

I'm not worked up at all. I do think it's an interesting discussion, though! On the above point, we agree completely.
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Absolutely. I do the same thing.

Perhaps this article by Pit Schubert is what you were thinking of? From http://www.uiaa.ch/article.aspx?c=231&a=147

If I recall your post correctly, you said exactly that, and then in the next paragraph you said you sometimes clip both pieces together, but didn't explain under what circumstances. This left me scratching my head, thinking "hmm, that could be bad..."
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In a later post, you give your reasons for putting both ropes on a single piece. This was helpful to seeing your perspective.

I just wanted to point out the fact that just because a climber falls past both pieces, does not mean that both ropes will share the fall.