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General Climbing Discussion

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Double, twin or single rope ...? 24-May-2004 At 2:22:50 PM shmalec

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Good find Mat. Interesting stuff.
Can I tentatively venture a simple explination…..no promises though. :-)

Forget everything else for a minute and just think in terms of stiffness. Intuatively, we know that a bungy cord is not very stiff (its stretchy) and has a very gradual, low impact force when you fall on it. On the other extreme, a steel cable is very stiff (its hard to stretch) and would arrest your fall with a sharp jolt and high impact force.

The difference between one rope and two is like that but not as extreme. One rope is less stiff (more stretchy) and will give a slightly lower impact force. Two ropes are more stiff (less stretchy) and will give a slightly higher impact force.

By impact force I’m talking about the “pull” of the rope on the climber. But the principles apply to the protection as well.
For any given fall, the stiffness drives the impact force, rope stretch and time to arrest fall. They are all related.

I think the recommendation for clipping both to the first bit of pro came from John Long's "How to Rock Climb" series of instruction books (for what its worth).

Don’t know if this helps anyone. My personal opinion is that its pretty academic in the end. Small differences in the way you place your protection, whether or not you wear a helmet, grease your hands up with sunscreen or get bitten by a bull ant mid pitch have more impact on your safety. But its an interesting problem anyway.