Half vs twin

Just bought a set of sterling photon fusions and was wondering because they r rated both for half and twin use if I can clip them in half or twin alternating on the same pitch? If not then why?

Not wise.
Once you've clipped as per a double rope, a fall can make one strand go tight while the other stays slack. If both strands are held side-by-side in a single carabiner basket (as per twin rope technique) you could melt the sheath where they run against each other.

from mammut ...

Hello (named removed),

you had a question on your Mammut rope Phoenix 8mm and whether it can be used in twin and half rope technique in one single pitch. This is the case, you can always clip the two rope strands as twins, then split them as doubles, join again etc. This is exactly the advantage of half ropes compared to twin ropes where you always need to clip both ropes.

Hope this helps you,
best regards from Switzerland,

(named removed)
Productmanager Climbing Equipment

you're going to get different answers from different people. but, regardless of the answer, why would you want to use double/half ropes as twins? i can't picture a scenario where there would be any reason to do so.

I'm with Gregger Man on this one even though mammut said otherwise. It is not a good idea because the ropes can move at different speeds when they are clipped as doubles, so if they are going through the same biner the one catching the fall can potentially melt through the other one.

I was taught the ropes by a friend who learned a lot from swiss guides and he taught me it was fine to alternate double and twin technique (he had the phoenix btw). I have since changed my mind and I stick to either twin or double for a pitch.

Crag Dweller wrote:you're going to get different answers from different people. but, regardless of the answer, why would you want to use double/half ropes as twins? i can't picture a scenario where there would be any reason to do so.

There are a couple reasons; mostly convenience and rope stretch.

First belaying with twin technique is just alot easier than feeding out slack on one rope and taking in slack on the other. Sure double technique is not that hard, but maybe you are just teaching someone or just don't want to deal with it on a straightforward pitch.

The rope stretch is the biggest one though. Getting caught by one of the doubles has alot of stretch and lets you fall alot further, possibly hitting a ledge or loosing some ground you'd rather not reclimb. So if these are issues you expect on a pitch switching to twin technique makes alot of sense.

I was on a pumpy climb recently using double technique where every time I fell the skinny little double stretched a long ways and made me climb the same pumpy crux again. In hindsight I wish I would have done that pitch with twin technique.

David Appelhans wrote: There are a couple reasons; mostly convenience and rope stretch. First belaying with twin technique is just alot easier than feeding out slack on one rope and taking in slack on the other. Sure double technique is not that hard, but maybe you are just teaching someone or just don't want to deal with it on a straightforward pitch. The rope stretch is the biggest one though. Getting caught by one of the doubles has alot of stretch and lets you fall alot further, possibly hitting a ledge or loosing some ground you'd rather not reclimb. So if these are issues you expect on a pitch switching to twin technique makes alot of sense. I was on a pumpy climb recently using double technique where every time I fell the skinny little double stretched a long ways and made me climb the same pumpy crux again. In hindsight I wish I would have done that pitch with twin technique.

The second scenario, to prevent decking as a result of rope stretch, seems to me like one that might justify using doubles as twins.

As for the difficulty of double rope technique, it's not really. It takes about 2 minutes max to get it down. And, IMO, using twin technique to compensate for bad double rope technique is just a bad idea. Kind of like using a gri gri to compensate for bad belay technique.

Gregger Man wrote:Not wise. Once you've clipped as per a double rope, a fall can make one strand go tight while the other stays slack. If both strands are held side-by-side in a single carabiner basket (as per twin rope technique) you could melt the sheath where they run against each other.

Interesting, I've never heard this before. Has this actually happened before in real life or in a test? Sounds a little far-fetched, but I could be mistaken. Even when belaying the whole pitch as twins both strands aren't going to engage at exactly the same time. Where did you get this idea from?

Cory wrote: ...Where did you get this idea from?

I've heard it repeated here and on the Taco, but the only place in print I can find the idea is in Extreme alpinism: climbing light, fast, & high By Mark Twight p.162
It makes intuitive sense, but I've never done any tests to verify it. Whether on not one strand would damage the other would depend on the shape of the carabiner and the direction of the fall, etc. Eh, It might be fine.
But I still don't think it's wise if you want to take care of your ropes.

The only risky situation I see is when one rope is moving (under load) and the other isn't. That would concentrate all of the wear on one spot and create a problem. In twin rope lead falls, both ropes are moving, so this isn't a problem.

The only situation I can come up with where this could happen is a fall while using the double rope technique (i.e. only one rope clipped through the highest piece -- the one holding the fall), if you had clipped twin lower on the pitch. The rope catching the fall will pull tight, and run through the biners as the belayer stops the fall. The other strand will not be pulled upward, making it possible for it to be rubbed by the loaded strand down where the ropes were clipped as twins.

I think it would still take a pretty specific scenario to actually damage the untensioned line. There would need to be some direction change through the piece, and the untensioned line would probably need to be pinched against the side of the biner in some way.

So, I guess it's possible, but it seems unlikely. I'd love to hear from someone that actually uses the system as this is all just internet speculation...

Its fine just clip them each through their own biner. For example, pitch starts with 2 cracks 3 feet apart. Clip one rope into gear in right crack and one into gear in left crack. After 35' one crack ends and so you start clipping both ropes into each piece (since there is no longer a right and left) but you do clip each on its own biner. Then after another 25 feet you have a traverse right for 15' then back left to above the original line so you clip the right rope into the pro on the traverse(s) then when you are back above the original line you resume clipping both ropes through each piece (although for rope drag issues you may want to skip clipping the right rope into the 1st piece after the traverses). It also makes it much safer for your 2ed during the traverse....

Rich, I've done one or the other. At directional changes or traversing, if I'm using half-technique with 2 Seconds, then I'll use two slings of different lengths into one pro point (it's easier with alpine draws). I've not heard any manufacturer say it's alright to combine techniques in the same pitch. The same overall climb using either one technique or the other as you switch pitches depending on terrain, yes.

Buff Johnson wrote:I've not heard any manufacturer say it's alright to combine techniques in the same pitch.

I hadn't either until I read the comment above (third post) that was supposedly from Mammut.

Aside from nylon movement differences when combining techniques on the same pitch, I'm concerned about potential loading behaviors on biner gates, twisting out slings, and unintended loading directions on pro.

As well, the half-technique is 'supposed' to load distribute and lessen force between pro, so I would like to keep that technique as-intended and not combine into twin on the same pitch. But, I guess that's disputed and I can see why; Sterling, I think offered that one in some backyard testing.

Really, the biggest rule I think is these systems are meant as a possible last-chance in tenuous terrain if you blow it when falling isn't an option while leading. Twight does have a point, this is meant for light and fast in a technical alpine setting. If falling is expected, I'll just use a single rope, bring a tag if needed, or lessen my level of acceptable terrain risk in some way.

as mentioned by someone above ... i have used it on the first few bomber pieces or bolts to prevent a ledge fall/deck where the half rope stretch is not a good thing ... afterwards the pitch breaks off and wanders abit ... so a switch to double rope is helpful

its also useful when you eff up a bit, intending to do the pitch as twins all the way, but find out mid pitch its better as doubles ... im sure some people here never screw up ... but hey thats the internet

to put it simply if mammut tells me its fine, and they have liability ... im not worried about it ... perhaps their ropes are "special"

i dont commonly use it ... but its useful to know it can be done

Gregger Man wrote: I've heard it repeated here and on the Taco, but the only place in print I can find the idea is in Extreme alpinism: climbing light, fast, & high By Mark Twight p.162 It makes intuitive sense, but I've never done any tests to verify it. Whether on not one strand would damage the other would depend on the shape of the carabiner and the direction of the fall, etc. Eh, It might be fine. But I still don't think it's wise if you want to take care of your ropes.

This is how urban legends start.

Copperhead wrote: This is how urban legends start.

I'm also skeptical of armchair speculations about gear failure, but I don't think this particular point rises to the level of urban legend.

International Handbook of Technical Mountaineering By Pete Hill, p.215
Can friction damage the sheath when you combine double rope and twin rope technique on a pitch?

i agree with whoever said that if you fall on twin ropes clipped into the same gear then they are both moving, one will not get stuck and rip through the other, plus they are typically both skinny 8.5m or so, so there should be plenty of room in a 'biner basket for both. Used half/twin for the first time this summer on the diamond and found them to be awesome, super light, you can split the rope-load while carrying gear in, you can split ropes if you want on wandering pitches and you've got two rap lines for the end of your climb. Thinking of purchasing half/twins for next year's alpine adventures.

Gregger Man wrote: I'm also skeptical of armchair speculations about gear failure, but I don't think this particular point rises to the level of urban legend. International Handbook of Technical Mountaineering By Pete Hill, p.215

while i appreciate the quote ... i still take mammut's word over the internet or some book

they make and test their ropes, should they give inappropriate advice in its use, they suffer the consequences ... climbing companies are pretty careful about such things

perhaps there are actual tests out that show otherwise? .. if so we can can send those to mammut ...

Gregger Man wrote: I'm also skeptical of armchair speculations about gear failure, but I don't think this particular point rises to the level of urban legend. International Handbook of Technical Mountaineering By Pete Hill, p.215

Perhaps, but it is being overblown at the least. Trust the manufacturer.

I'm curious, too.
I just emailed PMI and Bluewater to see if they can shed some light.
Stay tuned.

edit to add the wording of my question to PMI & Bluewater:

Hi.
I'm wondering if someone on the technical side would care to comment on this discussion:

mountainproject.com/v/half-…

The crux of the matter is whether or not it is possible/likely that the sheath of a half/twin rope pair would be damaged if a climber used half rope technique for part of a pitch, then twin clipping technique before a hard fall. It seems reasonable to me that one strand would be weighted first and run faster than the other, and that the friction between the two clipped into a single carabiner at the high point could damage the sheath.

Fact or opinion?
Have you done any tests that would prove or disprove this hypothesis?

Cheers,
-gg