rope diameter

[mountainsandsound]

I am curious- how small in diameter can you go until you notice that catching a fall is more difficult? I have a 8.5 mm that I use on glacier routes and have used on easy alpine rock sections where I expected that forces would be pretty low because the terrain was not vertical. Have not tried to catch a lead fall with it though.

[genepires]

ropes have different characteristics other than diameter. Elongation and impact forces will be more relevant to your question than diameter, assuming that your belay device is rated to work for a 8.5mm rope. Typically the smaller diameter ropes have more elongation and lower impact forces but that may not be 100% true.

 

If your inferred question is wether your 8.5mm rope adequate for catching vertical leader falls, then answer would lay with evaluating all the points in the belay chain are adequate.

-Is the belay device good for that size rope? friction goes down as size goes down. (insert snickering here) Rope size people!

-Is the rope being used as designed? (is it a single rope or a double rope?)

-Is the rope still in good enough condition to be used this way?

 

If the answer is yes, then the rope is fine. There a shit ton of other questions about lead climbing but for your original question.

[kurthicks]

If you don't want to buy a new rope, just have the leader tie into the middle of the rope and belay on both strands. Shorter pitches, but it will give you a much greater likelihood of catching a fall and a decreased chance of cutting your rope on sharp terrain features.

[tvashtarkatena]

Stiffness, as in other systems, is key to a good alpine rock rope. Stiffer ropes tangle less when pulled. There's a huge difference here from brand to brand. Glacier ropes? Use whatever.

[mountainsandsound]

Thanks for the responses. I figured I could just tie into the middle for a steeper pitch if need be. Did not know that fact about stiffness and pulling post rappel. Makes sense, good to know.