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half/twin ropes
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By Dusty
From Fort Collins
Jan 12, 2010
just teasin' the sharks...

Hi,

PMI Verglas 8.1 half/twin $159

vs

Mammut Genesis 8.5 half $135

Which way do I go? The main use for the ropes will be summer (read: rock) alpine routes. Also, how does half/twin differ from half? I understand why twins can't be used as halfs, but I don't understand why half ropes couldn't be used as twins...

Thanks in advance.

Dusty


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By Andy Laakmann
Site Landlord
From Bend, OR
Jan 12, 2010
Racked and loaded... name that splitter behind me? Hint, its on Supercrack Buttress

I heart my PMI Veglas. They handle like butta and it is nice to know you can use them either as half/twin. My understanding is the difference between half/twin is due to impact force, whatever that is ;)


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By timt
From Wheat Ridge, CO
Jan 12, 2010
on lead, Mean Green Cody,WY

have the mammuts and no complaints. one thing to keep in mind is that the skinnier the ropes the more twisting, weird knotting, catching up & wind issues you will have rappelling with them. on the other hand, less to carry on the approach.
like andy says, seems like the reason halves can't be used as twins is impact force; twins are tested with drop forces of 80kg used together. half ropes are tested individually at 55kg drop forces. HOWEVER, seems like this relies on the theory that both ropes will have the exact same tension. that NEVER happens in the real world. i regrettably admit to taking a 30-footer on my mammut genesis being used as twins. no issues and no gear blown.


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By "Canada" Eric Ruljancich
From Tucson, AZ / Vancouver, BC
Jan 12, 2010
Mt Gimli, Valhallas, BC, Canada

From an earlier post of mine:

Technically both twin and half ropes are double rope systems. For clarity twin ropes necessitate the clipping of both ropes into every piece of protection. Half ropes (commonly erroneously called double ropes) are designed to be alternatively clipped to each piece of protection.

Twin ropes are individually designed with a low impact rating and therefore a quite stretchy, needing to be used together to provide the correct amount of energy absorption. They are also not rated for falls on an individual strand. Bottom line if you use twins as half ropes you may take a very long ride.

Half ropes have higher impact ratings, given that they are essentially operating as a single line during a fall. If they are clipped together as twin rope system they can create a much higher level of impact, potentially ripping out your gear.

Thus, twin ropes should not be used in a half ropes, and half ropes should should not be used as twins.

With all that said, several manufactures now make ropes that are rated both as half and twins - a bit of compromise on both ends. I own such a system, the 7.8 Monster from Meteolius and highly recommend it, having the best of both worlds. The PMI Verglas is also another option.


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By Dusty
From Fort Collins
Jan 12, 2010
just teasin' the sharks...

Great! Thanks for the info.


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By pfwein
Jan 12, 2010

I have Mammut Genesis. I believe they are approved for twin as well as half, but I don't seem to be able to find the product hang tag that came with them, and the tape markers on the ends of the ropes (which I think may also have this info) are gone.

I like and recommend them, but beware that the weight of the ropes near the end of long, steep pitches will be quite a bit more than with a single rope and this could be a reason to get a thinner set. I may get thinner next time, but that raises another issue: the thought of taking long falls onto a single, thin 1/2 rope is a bit terrifying to me. (I'm easily terrified though.)


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By saxfiend
Administrator
From Decatur, GA
Jan 13, 2010
Relaxing at the P1 belay of Fruit Loops at Rumbling Bald.

pfwein wrote:
I have Mammut Genesis. I believe they are approved for twin as well as half, but I don't seem to be able to find the product hang tag that came with them, and the tape markers on the ends of the ropes (which I think may also have this info) are gone.

I still have the tag that came with my Genesis ropes, and they are not dual use, only rated as half ropes.

pfwein wrote:
beware that the weight of the ropes near the end of long, steep pitches will be quite a bit more than with a single rope

I've gotten a lot of long multi-pitch mileage on my Genesis, and rope weight has never been an issue for me.

JL


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By Scott McMahon
From Boulder, CO
Jan 13, 2010
Bocan

+1 for the genesis...yes, they are a tad thicker, but they are a soft and great handling rope.


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By pfwein
Jan 13, 2010

OK, but Mammut's product literature is certainly "interesting" regarding whether a half rope may be used as a twin. As I read it, Mammut says you can use their half roes in either twin mode or "standard" half rope mode. From their brochure:

"Half ropes, with regard to strength and
weight, lie between single and twin ropes.
They only offer standard safety when they are
used as a pair. But here you have the choice
between twin rope technique, where both
ropes run parallel through the protection and
half rope technique, where the «left» and
«right» ropes run separately through different
protection points."


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By Buff Johnson
Jan 13, 2010
smiley face

Eric Ruljancich wrote:
If they are clipped together as twin rope system they can create a much higher level of impact, potentially ripping out your gear. Thus, twin ropes should not be used in a half ropes, and half ropes should should not be used as twins. With all that said, several manufactures now make ropes that are rated both as half and twins - a bit of compromise on both ends.


It isn't as much a compromise as it is a strand that can meet the requirements of both drop tests.

While clipping both strands on the half rating does create higher impact on the pro; it's not catastrophically higher -- i.e. this isn't a case where the system goes into a static material versus a dynamic material. Which is why it really isn't that big a deal to have a rope that can be either twin or half rated. You just want to stay with only one method during the climbing pitch.

What makes a half (other than the drop test criteria), is the climbing method. Under perfect conditions, the drop mass will have some sort of distribution between two independent protection points. Which is why the standard doesn't use a full mass for the cert.

But, I find my method is usually more to rope drag, I may alternate strands to begin with, but then clip the next 3 with the green strand then the next 4 with the purple strand; this takes away the half method and now I'm just using the halfs as singles.


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By saxfiend
Administrator
From Decatur, GA
Jan 13, 2010
Relaxing at the P1 belay of Fruit Loops at Rumbling Bald.

pfwein wrote:
OK, but Mammut's product literature is certainly "interesting" regarding whether a half rope may be used as a twin. As I read it, Mammut says you can use their half roes in either twin mode or "standard" half rope mode.

That is interesting; I hadn't seen that in their literature.

JL


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By Bad Sock Puppet
Jan 13, 2010
Bad Sock Puppet

Mammut Genesis! I use them on everything from alpine to ice and I can't wait to get a new set.


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By J. Albers
From Colorado
Jan 13, 2010
Bucky

Dusty wrote:
Hi, PMI Verglas 8.1 half/twin $159 vs Mammut Genesis 8.5 half $135 Which way do I go? Thanks in advance. Dusty


Neither. I much prefer Blue Water Excellence 8.4mm half ropes. I have owned 3 pairs of these ropes and I always end up retiring them because of age, not because the ropes are worn out. And yes, I abuse the heck out of them...ice, alpine rock etc. Keep in mind, that I am perhaps bias. I have had bad luck with Mammut ropes.

Just my opinion.


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By brenta
From Boulder, CO
Jan 13, 2010
Cima Margherita and Cima Tosa in the Dolomiti di Brenta.  October 1977.

Buff Johnson wrote:
Under perfect conditions, the drop mass will have some sort of distribution between two independent protection points. Which is why the standard doesn't use a full mass for the cert.

That's what I thought too, but apparently it isn't so. The reason for the 55 kg mass is that a half rope should hold at least one 80 kg "UIAA" fall. (No assumption of strict alternation.) However, reliably testing that is difficult. It's better to test for multiple falls with a reduced mass.

To the OP: I like my Verglas.


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By kevinhansen
From Albion Idaho
Dec 3, 2012
Why I do it...

Sorry to dig up a very old thread, but anyone care to comment of the PMI Fusion half/twin 8.6mm?
Maybe these were made after this thread started, but there isn't a ton of info on these unique ropes.
cascadeclimbers.com/forum/ubbthreads.php/topics/65674/
This is about all I could find.
Kevin


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