10mm vs. 11mm pmi ez bend rope

[wkb3rd]

It's time for me to purchase a rope and I can't figure out which size rope I want.. I like the feel of the 11mm because that is what I've used to this point but I'd like to hear some input from people who've used both.. Any suggestions?

[caverdoc]

I've been going to 10mm rope lately. It seems to track through my ascenders a bit better. For my rescue gear I use 11mm, a bit more safety for the two-person loads.
If you really want to live on the edge, use 8 or 9mm rope.
Doc K

[Lava]

I love 10mm rope. It feeds much better through my micro rack, and is a lighter and smaller load on the way to the cave. But you may want to consider if your rigging style is conducive to 10mm rope. If you practice mostly IRT (Indestructible Rope Technique) as opposed to a more European-style, 10mm may not be robust enough.

[fuzzy-hair-man]

I am mostly used to 10mm rope but tried 11mm in the US recently, I do prefer 10mm, as said before 11mm rope meant that my descender (bobbin) was pretty slow compared to what I'm used to and when ascending I had to clamp the rope with my feet almost all the way up the rope, usually I only need to clamp it for the first metre or so.

Still, Id be happy to use 11mm rope again, if you go 10mm you may have to change your rigging style somewhat compared to 11mm rope but it still has a reasonable safety factor IMO, just watch it carefully in your first couple of months until you know how it wears and that sort of thing.

We generally practice Alpine Rigging so I don't know how 10mm will respond to IRT as our ropes are generally retired because they get too stiff or old and rarely see much sheath wear.

I have also used 9mm rope once, it looks lots thinner, so it takes a little getting used to and you have to be careful to avoid any rub points but it is easy to handle and tie knots in etc quicker descending too.

[hank moon]

our ropes are generally retired because they get too stiff or old and rarely see much sheath wear.

Huh??? Send 'em my way, matie! How come you retire before the sheath is worn? I almost never retire a rope - they just get shorter and shorter...

[fuzzy-hair-man]

Generally I think they get so stiff you can't tie knots in em. and you end up hauling in packs as ballast so you can move down a rope
That said the club had bought new rope a couple of years before I joined so we haven't retired any of that rope yet.

Most of them are club ropes but they have suffered very little sheath damage they just get STIFF and shorten which is a pain because some were cut at lengths close to what was required to do some of our more popular vertical trips, means we are going to have a knot crossing a couple of metres off the deck

Correct me if I'm wrong, but technically, ropes shouldn't be used if they are beyond a certain age? (5 or 10 years? I can't remember ) because the club owns and provides the ropes (and some other gear) for use by members the club has to be careful to be seen to be doing the right thing (retiring gear when appropriate) because Australia has lawyers too

I figure if your ropes are being retired because of age and the fact they are stiff then you must be rigging them alright. provided of course you actually go caving with them (we do OK but not as much as I'd like.... )

Perhaps we ought to be using 9mm then

[cave rat]

I generally use 11MM PMI Pit or Maxi-Ware and I have a 300' High Line Rope.

I use to have a piece of 150' EZI Bend Rope. That was the first piece of rope I ever owned. I did not like it. It was like climbing on Blue Water.

I have rappelled and climbed on 10MM before. My Cows Tail is constructed out of 10MM.

[justinmiller]

10mm rope might be faster, but i like to have just a little more strength in my rope, so i go with PMI's pit rope, but who really needs a 29.1kN rope anyway. both are probably fine. it all depends on the user.

[fuzzy-hair-man]

I was under the impression that the thicker ropes just had a thicker sheath on them so they achieved more abrasion resistance, if you rig with less rub you don't need as thick a rope. Any extra strength was sort of accidental, as the extra strength was gained by adding the extra strands in the sheath.

[RescueMan]

How come you retire before the sheath is worn? I almost never retire a rope - they just get shorter and shorter

Heresy!

Generally I think they get so stiff you can't tie knots in em.

Ever try washing them?

Correct me if I'm wrong, but technically, ropes shouldn't be used if they are beyond a certain age? (5 or 10 years? I can't remember

Ah, yes - the perennial question. A question (as you suggested) that is answered most often by lawyers: be conservative, retire after 5 years or any severe use or if inspection displays significant wear or defects.

But, particularly for static ropes, there is little if any strength loss from simple aging protected from sunlight - UV degrades nylon over time. There is evidence that dynamic ropes lose their energy-absorbing quality with time and use.

I have a 1/2" Blue Water static line that's still quite functional after 16 years.

I was under the impression that the thicker ropes just had a thicker sheath on them so they achieved more abrasion resistance. Any extra strength was sort of accidental, as the extra strength was gained by adding the extra strands in the sheath.

Larger diameter rope has proportionally more strands in BOTH the core and the sheath, and its the combination which determines its strength.

Max-Wear type ropes have a higher ratio of their fibers in the sheath and EZ-Bend type ropes have a lower sheath/core ratio, even though the overall strength rating might be identical.

Also affecting the "hand" or feel of a rope and its abrasion resistance vs flexibility, is the density of the weave of the sheath, the tightness of its sheath to the core, and the fiber treatments (such as drycoat).

Bottom line: larger diameter rope has more surface area to absorb abrasion - smaller diameter rope has less surface and wears/cuts through more quickly (also stretches more with the same load and so wears more at rub points).

- Robert

[fuzzy-hair-man]

Generally I think they get so stiff you can't tie knots in em.

Ever try washing them?

After every dirty or muddy trip. They need to be washed / soaked with a mixture with some (not too much) fabric softener though, hopefully that will help a bit.

Bottom line: larger diameter rope has more surface area to absorb abrasion - smaller diameter rope has less surface and wears/cuts through more quickly (also stretches more with the same load and so wears more at rub points).
- Robert

That was my impression thicker ropes = greater abrasion resistance but not necessarily more strength.

[RescueMan]

That was my impression thicker ropes = greater abrasion resistance but not necessarily more strength.

That's NOT what I was saying. And now I'm not sure what you mean by "thicker".

If you're talking larger diameter (which is what I thought you were, since the thread is 10mm vs 11mm), then the strength is proportional (all other things being equal) to the cross-sectional area of the rope.

10mm rope is generally rated at about 6500 lbs MBS and 11mm rope at about 8000 lbs MBS, with safe working loads about 10% of the MBS.

As static lines (<6% stretch @ 10% MBS), the smaller diameter rope will stretch more with the same body weight than the larger diameter rope. Less stretch, in addition to more surface area because of the larger diameter, results in less abrasion damage.

- Robert

[fuzzy-hair-man]

I agree that could have been worded better my mistake. I guess my point (I my mind at least) was that a good reason to get a 11mm rope over a 10 mm rope was because you could expect the 11mm rope to be more abraison resistant. For recreational caving (single person loads) any increase in strength is largely irrelevant, as you should not be outside the safe working load for either rope. Would you agree ?

[RescueMan]

For recreational caving (single person loads) any increase in strength is largely irrelevant, as you should not be outside the safe working load for either rope. Would you agree ?

Agree.

But other issues to consider are stretchiness and speed of descent, as a smaller rope will be faster in the same rappel device.

On the other hand, a thinner rope is often easier to ascend (other than the bounce) as the cams of the ascenders dont' drag on the rope as much - also easier to downclimb.

- Robert