Roca Migu and rope types

[Blake]

In my quest for a 1/2 rope, I'd narrowed down my options to the Roca Migu and Mammut Phoenix. PDX's ClimbMax appeared to be selling the Roca Migu, but listed it as 7.8mm, and as part of a "twin setup", not 8mm and a 1/2 rope as stated on the Roca ropes webpage. I emailed the shop about this, and was told

" The Migu that we have is an 8mm, and ideally it is a twin, not a double. Some companies are going to call their eight a twin, and some companies are going to call their eights doubles. The rope that we have is the Migu, and the specs you have are correct."

 

Now I was under the impression that the CE certification tests for the three different types of ropes were all different, and companies can't call a certified half rope a "twin rope" merely because it's skinny, and they can't call a certified twin rope "double/half" because the rope wasn't tested to withstand falls on one strand. Is it really safe or responsible to just throw these terms around like that? Is it true thatif you treated 1/2 ropes as twins and clipped both to a single carabiner, that they exert extra force when you fall? FYI the Roca Web Page shows the Migu as a 1/2 rope only. How common is the attitude that skinny ropes can be climbed on using twin technique even if they are intended to be used as double/half ropes?

[thelawgoddess]

" The Migu that we have is an 8mm, and ideally it is a twin, not a double. Some companies are going to call their eight a twin, and some companies are going to call their eights doubles.

i am not impressed by that statement ... which makes it sound like they think ropes are rated solely based on diameter. wtf? when i doubt about factual matters i would be inclined to put more trust in a disrtibutor than a salesperson. but anyway, the migu are half ropes. you can use halfs like twins if you want (and some people even use short sections as singles for some glacier and alipine stuff), but you should not use twins as halves. there have been at least a couple of threads in the past with more technical gibberish to explaining why. (pms sells migu and i'm sure they'd be happy to answer any questions you might have about them.)

[catbirdseat]

If you get 8 mm half ropes, you might be disappointed in the durability.

[robert]

If you get 8 mm half ropes, you might be disappointed in the durability.

CBS,

Can you elaborate? Is it something about the diameter that makes them more prone to snags in the sheath, thread count to radius or something? Is the material slightly different? If you are meaning that it won't hold as many falls I can understand that, but I don't understand why it would not wear as well as a 9, 10 or 11mm rope.

[Blake]

you can use halfs like twins if you want

 

TLG.... are you sure on this one? I've heard that this increases the forces on your protection, and on you, when you fall. Maybe it's one of those things where you can do it, but it's not always optimum.

[robert]

There are a few ropes that can be used (read "are rated for use") both ways. The PMI verglas is rated both ways. Those that are rated for use only as a twin or only as a half should only be used as they are rated. Using a twin as a half could result in too much elongation or a failure and using a half as a twin could result in a failed piece of pro as there is not enough elongation.

[thelawgoddess]

you can use halfs like twins if you want

 

TLG.... are you sure on this one? I've heard that this increases the forces on your protection, and on you, when you fall. Maybe it's one of those things where you can do it, but it's not always optimum.

yes, it does and it kind of defeats the purpose of buying half ropes to begin with ... but i believe you still *can* do it if for some reason you feel you really need to. maybe i'm wrong here, but i haven't really heard any super-convincing arguments to that effect.

[Dr_Flash_Amazing]

Why screw around with all these extraneous cords? Tie into your 9.6 and take it to the chains!

[jmace]

Half like twins? I thought it was friction on the ropes that made it unsafe to clip two fat strands to the same biner, if you want to use halfs like twins you just clip two biners to te same piece. Maybe im wrong cause i never use twins and I never clip my halfs to the same piece.

[Winter]

My understanding is that friction in the same biner is only an issue if they are different diameter ropes since they will stretch at different rates.

[rbw1966]

Chris is sorta right. The reason you need two biners if you are clipping half-ropes in the same piece is presumably you are not doing that on the entire route but rather on that one piece. One rope will stretch differently then the other.

[Winter]

Right right. If you are using halfs of the same diam. and clipping every piece then it should be ok. That said I don't think I've ever seen a report of ropes failing this way.