Welcome to SP!  -
Areas & RangesMountains & RocksRoutesImagesArticlesTrip ReportsGearOtherPeoplePlans & PartnersWhat's NewForum

Which alpine rope should I buy?

Post climbing gear-related questions, offer advice. For classifieds, please use that forum.
 

Re: Which alpine rope should I buy?

Postby Matt Lemke » Wed Sep 25, 2013 12:49 am

ExcitableBoy wrote:
Matt Lemke wrote:I have a question...what is the proper way to double up a half rope for climbing? I hear this being said all the time but can't think of the correct way to tie into a folded over rope.


Rewoven figure eight on a bight.

That's what I thought but I can imagine it would be difficult to get the knot RIGHT in the middle so that each strand was exactly the same length which would be required if you simul-climb. Does this not matter too much if one strand is a couple inches longer?
User Avatar
Matt Lemke

 
Posts: 514
Joined: Fri Jan 01, 2010 8:34 am
Location: Red Lodge, Montana, United States
Thanked: 90 times in 71 posts

Re: Which alpine rope should I buy?

Postby norco17 » Wed Sep 25, 2013 12:52 am

Chad
Different shock absorbing abilities and strengths. Some are rated as both half and twin others are not.

As far as being manufactured differently. A rope is a rope. Sort of.

EB's first post above is spot on.
User Avatar
norco17

 
Posts: 817
Joined: Tue Dec 02, 2008 12:53 am
Location: riverside, California, United States
Thanked: 162 times in 105 posts

The following user would like to thank norco17 for this post
mrchad9

Re: Which alpine rope should I buy?

Postby norco17 » Wed Sep 25, 2013 12:55 am

Matt Lemke wrote:That's what I thought but I can imagine it would be difficult to get the knot RIGHT in the middle so that each strand was exactly the same length which would be required if you simul-climb. Does this not matter too much if one strand is a couple inches longer?



If you are simulclimbing you are not going to fall anyways right? If on a half then each strand is supposd to be strong enough independently anyways. The second strand is there for redundency. A twin would be a bigger issue, but you never have the exact same amount of rope out when belaying anyways.
User Avatar
norco17

 
Posts: 817
Joined: Tue Dec 02, 2008 12:53 am
Location: riverside, California, United States
Thanked: 162 times in 105 posts

The following user would like to thank norco17 for this post
Matt Lemke

Re: Which alpine rope should I buy?

Postby MoapaPk » Wed Sep 25, 2013 2:07 am

I think the difference is in the testing
http://www.sterlingrope.com/media/docum ... manual.pdf

Impact Force: Tested during the first factor 1.739 fall (4meter fall on 2.3meters of rope).
- Single Ropes: Impact must be less 12 kilonewtons (kN) using an 80kilogram mass.
- Twin Ropes: Same as Single ropes, but using both strands during the test.
- Half Ropes: Impact must be less than 8kN, tested using a 55 kilogram mass.
Falls Held: Number of falls rope holds before breaking.
- Single Ropes: Must hold 5 falls of an 80kg mass.
- Twin: Must hold 12 falls of an 80kg mass. {I'm quite sure this is also with both ropes tested together}
- Half: Must hold 5 falls of a 55kg mass.

I rarely see half ropes that are less than 8.5 mm diameter; but often see twins 8mm or less.

I'm sure that rope makers test their ropes before submitting them to UIAA; they would probably love to have 7.8 mm ropes that pass the half tests, but if they have doubts they will pass, the rope is submitted as a twin.

On dynamic ropes, the impact force rating is NOT a breaking strength rating; it's an approximation of the maximum force a climber will feel at the end of the standard (test) fall. This concept originated long ago, with the testing of parachute harnesses. If a rope stops a fall and doesn't break, but breaks your spine or pelvis, that's still not a good thing.
User Avatar
MoapaPk

 
Posts: 7598
Joined: Fri May 13, 2005 7:42 pm
Location: Las Vegas, Nevada, United States
Thanked: 735 times in 474 posts

The following user would like to thank MoapaPk for this post
Wout

Re: Which alpine rope should I buy?

Postby Vitaliy M. » Wed Sep 25, 2013 4:02 pm

Matt, usually if I use it for climbing (leading etc) I tie in the middle with a figure 8 on a bight. And the other person ties to other ends with two figure 8s.
User Avatar
Vitaliy M.

 
Posts: 1011
Joined: Mon Mar 28, 2011 1:23 am
Location: San Francisco, California, United States
Thanked: 287 times in 215 posts

Re: Which alpine rope should I buy?

Postby Wout » Wed Sep 25, 2013 5:45 pm

Thanks all, very helpful!

I think I'll buy two half ropes of 50 mtrs. 50 mtrs so I can also take just one rope on easy glacier routes.

I'll take one half rope when I'm max with 3 persons and the route consists of a lot simul climbing and some short lenghts of 4th class. I'll double that half rope up, so the max length is 25 mtrs.

When I'll climb 5th class I'll take two half ropes, because of the length. Also when there are long abseils.

But I'm not so sure about the thickness? Is the handling terrible beneath 8,5 mm?
So the problems are:
Crevass rescue (prusik won't hold or what?)
twisting (while abseiling?)
Thinner rope will rather get stucked when pulling the rope back from abseiling?
How big are these problems?

For instance this comparison between two half ropes and there weight:
Tendon Master 7,8 mm 50 mtrs: 1900 grams
Tendon Master 8,5 mm 50 mtrs: 2400 grams

0,5 kg difference.. Is this worth it or not?
User Avatar
Wout

 
Posts: 2
Joined: Sun Sep 08, 2013 4:14 pm
Location: Nijmegen, Netherlands
Thanked: 0 time in 0 post

Re: Which alpine rope should I buy?

Postby ExcitableBoy » Wed Sep 25, 2013 6:17 pm

I've climbed on skinny ropes from 7.8mm-9mm. My preference is for a fatter rope (8.5mm) for a number of reasons as you have inferred:

-Prusiking a super skinny rope is more difficult, both because prusiks cords don't 'grab' a thinner rope well and the rope stretches more making it more difficult to ascend.

-Crevasse rescue is more efficient with a rope that has less elongation when using a Z haul system

-Rappelling on a super skinny rope on steep terrain is more difficult due to the ropes running through the rappel device faster, although this can be mitigated to some degree with a device designed for thin ropes.

-Thicker ropes are more durable and resistant to being cut over an edge. My ropes are Edelweiss 'Sharp' ropes, which have been engineered specifically for improved cut resistance over edges. This is important if using half ropes singly on rock.

I haven't noticed that thinner half ropes twist or get stuck more than thicker half ropes.

One thing to bear in mind, rope manufacturers have +/- 0.2 mm 'slop' in the diameter measurement, therefore the weight in grams per meter is a more accurate and precise measure. Two ropes with the same weight can, for example, have published diameters of 8.2mm and 8.6mm. This rope comparison chart is useful. If you read carefully you will find ropes with thicker diameters that are lighter than other manufacturers ropes that have thinner diameters:

http://www.promountainsports.com/blog/2 ... -compared/
User Avatar
ExcitableBoy

 
Posts: 2876
Joined: Wed Nov 09, 2005 9:33 am
Location: Issaquah, Washington
Thanked: 422 times in 306 posts

The following user would like to thank ExcitableBoy for this post
Fletch, Wout

Re: Which alpine rope should I buy?

Postby MoapaPk » Wed Sep 25, 2013 10:18 pm

Wout wrote:So the problems are:
Crevass rescue (prusik won't hold or what?)
twisting (while abseiling?)
Thinner rope will rather get stucked when pulling the rope back from abseiling?
How big are these problems?

For instance this comparison between two half ropes and there weight:
Tendon Master 7,8 mm 50 mtrs: 1900 grams
Tendon Master 8,5 mm 50 mtrs: 2400 grams

0,5 kg difference.. Is this worth it or not?


First, thanks for pointing out the Tendon ropes.

Is 0.5 kg worth it? I sweat bullets over 0.5 kg differences, then at the last moment throw in 2 kg of crap. If you are forced to carry lots of technical gear, that will probably exceed the mass of the rope.

I'm not a climber, not do I play one on TV. I mainly rap on 8mm ropes-- albeit static ropes. For extra friction I put a very light locking carabiner on the leg loop.

I've used prussiks just once in a "real" situation, and was thinking: boy, this would be a real pain in the cold, or if the rope were wet, icy, etc. Maybe you should check the recommended thickness for actual ascenders-- typically the minimum guaranteed is 8mm, though I suspect that's really indistinguishable from 7.8 mm.

Prusiks cord diameter is supposed to be a set fraction of the main rope diameter. I have some prusik loops made with 5mm polyester cord (stronger than nylon), and they seem to work pretty well (though my foot was in an approach shoe when in the loop-- might be painful with rock shoes). With thicker cord, if you pull out a few center strands (like a valdotain cord), the friction knot will lie flatter on the rope.

I suspect you will end up with more than one rope. The reviews of the 7.8 mm tendon look pretty good -- people actually using it for snowy climbs and so forth. Maybe you can contact those folks at
http://www.climbingreport.com/gear-revi ... half-rope/
directly for opinions.
User Avatar
MoapaPk

 
Posts: 7598
Joined: Fri May 13, 2005 7:42 pm
Location: Las Vegas, Nevada, United States
Thanked: 735 times in 474 posts

Re: Which alpine rope should I buy?

Postby coldfoot » Fri Sep 27, 2013 7:29 am

norco17 wrote:
Matt Lemke wrote:That's what I thought but I can imagine it would be difficult to get the knot RIGHT in the middle so that each strand was exactly the same length which would be required if you simul-climb. Does this not matter too much if one strand is a couple inches longer?


If you are simulclimbing you are not going to fall anyways right? If on a half then each strand is supposd to be strong enough independently anyways. The second strand is there for redundency. A twin would be a bigger issue, but you never have the exact same amount of rope out when belaying anyways.


I've never tried this, but dynamic ropes typically are rated at about 7-8 % static elongation under body weight, and about 30 % elongation under a UIAA test fall (which is much harder than any fall you would take hopefully). Even if you just consider the static elongation in half a rope length, it's pretty big, so you don't have to tie the strands exactly the same length for them both to take load in a fall.
coldfoot

 
Posts: 102
Joined: Thu Feb 19, 2009 12:58 am
Location: United States
Thanked: 14 times in 12 posts

Re: Which alpine rope should I buy?

Postby Fletch » Fri Sep 27, 2013 4:46 pm

ExcitableBoy wrote:In addition to how they are used, half and twin ropes differ in the way they are tested and rated. Half ropes are tested by dropping a weight on a single strand while twin ropes are tested by dropping a weight on both strands. There are ropes that are rated as both twin and half ropes.

Dan - So if the ropes are manufactured with the same materials in the same way (as to Chad's question), then there should be some rough conversion method between twin and half ropes, right? It's the same rope, just being measured/rated differently? Is this right? And to Anita's point, its just a different way to market the same product, right?

Thanks for this thread guys --- I've wondered this for years...
User Avatar
Fletch

 
Posts: 227
Joined: Mon Jan 09, 2012 5:46 pm
Location: Orange County
Thanked: 90 times in 49 posts

Re: Which alpine rope should I buy?

Postby MoapaPk » Fri Sep 27, 2013 5:03 pm

Fletch wrote:
ExcitableBoy wrote:In addition to how they are used, half and twin ropes differ in the way they are tested and rated. Half ropes are tested by dropping a weight on a single strand while twin ropes are tested by dropping a weight on both strands. There are ropes that are rated as both twin and half ropes.

Dan - So if the ropes are manufactured with the same materials in the same way (as to Chad's question), then there should be some rough conversion method between twin and half ropes, right? It's the same rope, just being measured/rated differently? Is this right? And to Anita's point, its just a different way to market the same product, right?

Thanks for this thread guys --- I've wondered this for years...


They have to make sure that twin ropes are sufficiently "soft" when used together in impact force tests (because that's how they are tested by UIAA). Again, I'm sure manufacturers test their skinny ropes for both categories, and don't submit them to UIAA (e.g. as half) if they think they will fail a particular test. Many people will use a single strand of a skinny rope on a glacier climb, and may ponder the softness and stretch issues for crevasses rescue.

There is a great paper on the physics of ropes somewhere on-line.
User Avatar
MoapaPk

 
Posts: 7598
Joined: Fri May 13, 2005 7:42 pm
Location: Las Vegas, Nevada, United States
Thanked: 735 times in 474 posts

The following user would like to thank MoapaPk for this post
Fletch

Previous

Return to Gear

 


  • Related topics
    Replies
    Views
    Last post

Who is online

Users browsing this forum: No registered users and 0 guests

© 2006-2013 SummitPost.org. All Rights Reserved.