UKC

Crawling about the house today with one ankle twice the size of the less damaged one, I have been researching climbing rope stretch. ( Fell a lot further than expected and caught both feet on a small ledge .)

All I have found to date.

The UIAA has standards for static stretch and maximum stretch in a fall.

The UIAA test notes the impact force in only the first test fall.

An American forum has recommendations for preloading a rope before top roping.

I also vaguely remember being advised to rest a rope after a leader fall and ideally retie the knot after changing ends.

Anybody know of any other recommendations or research?

In reply to Rick Graham:




So. If the rope has been preloaded, as in a short leader fall or lowering off, how long does the rope need to recover its initial absorbancy and how much more severe are the impact forces in subsequent falls?

Last week at the (Kendal) wall, on a rope about half way thro its lead rope life, we did a lot of full height routes in quick succession.
It was notable how the rope was soft and spongy to hold at first and only just long enough for the lower off. ( Kendal is on the safe limit for a 50m rope) I noted how the rope was noticably shorter at first than when it was new.
After a few routes the rope felt firmer to the touch and more like its original length.

We only climbed on one end and after about 20 lowerings off, the first leader fall felt really and surprisingly harsh.

No surprise really after rereading this typing up but the lack of guidelines and information is puzzling.

In reply to Rick Graham:

This explains a little.
http://blackdiamondequipment.com/en/experience-story?q=ask%20KP&format=...

In reply to Rick Graham:
TBH I think the UIAA/CE standards tell us all we need to know at least when combined with the knowledge the in most 'large' real world falls you will get perhaps 70% of max stretch given by the rope specification.

In short, unless you are falling dozens of times a month you'll always fall further than you think you will. If you buy a low impact force and hence higher stretch rope (e.g. Beal) you'll probably fall a bit further still.

The answer is simple. Either don't fall or climb with partners who are massively experienced at belaying high standard sport climbing and are therefore good enough to judge how best to belay falls to mimimise the chances of injury.