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Topic Date User

Top rope gear... 17-Oct-2007 At 11:25:03 AM anthonyk

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On 16/10/2007 anthonyk wrote:
>static ropes aren't completely static, they're just less stretchy. but
>since you've got 1-2x the length of the climb in rope out all the time
>you'll get plenty of bounce. its probably got more stretch distance than
>a "dynamic" lead rope at the first or second (or third or even higher)
>bolt.

fyi static ropes stretch between about 1-2% and dynamic ropes between about 5%-8% (8% is a maximum standard i think). so you get about 2.5x-8x more stretch distance (which determines the impact) for the same length of rope. on a 20m climb you're getting between 60cm and 30cm stretch on a static rope with 1.5% stretch (assuming anchor is minimal resistance). with a lead rope of 6% you'll get 24cm with 4m out, up to (theoretically) 1.2m with 20m out, although in reality the resistance of it going through all the quickdraws will reduce the effective amount of rope stretching significantly. if we say it halves the amount of rope stretching when you're at the top of the climb then you're getting about 60cm stretch.

in that example the static is giving btw 30-60cm stretch (maybe 20-50cm with some anchor friction) and the dynamic on lead giving btw 24-60cm (assuming friction takes half of it out of play at the top), basically the same. so there shouldn't be any issues if someone took more of a fall on the static either, not just weighting it, since its giving about the same amount of stretch that a dynamic would.