There’s been plenty of debate about the rope systems in ice climbing, weather to use single or half ropes in particularly. Some folks swear to the half ropes, whereas other insist that single ropes are better due to actually lower impact forces. So here’s my take on the topic. To orientate my view, I’m writing almost entirely from the perspective of multi-pitch ice climbing on pure waterfall ice. While I know that there are climbers with more experience under their belt, I hope the insights below are useful for fellow climbers, at least while figuring out their stand on the topic. I’ll dive into different rope systems once I’ve taken the beginners through the basic principles, if you’re an experienced climber you might want to skip the basic principles part.
Picture above: The ropes I’m currently using.
Basic principles
Ideally you would like to select a rope that’s light, long, has low impact force, as well as excellent handling and is durable. Unfortunately these characteristics are, mildly put, somewhat opposing. So lets put these in order.
So after these rope characteristics you’re down to two choices; The length and type, i.e. single vs. half ropes. While type question is somewhat complicated issue and I’ll dive into the topic shortly, the length is much more straight forward. For multi-pitch ice climbs that typically have several snow sections, 60 or 70 meters is in my opinion a good length. Longer rope makes the rappelling faster.
Single vs. half ropes
Generally speaking half ropes offer several advantages over single ropes. While climbing they allow lower rope drag because one can alternate clipping according to route so that ropes go straighter line. Half ropes also offer “naturally” longer rappelling distances due to two strands. In single rope system one needs to compensate that with a tag line. Further more half ropes offer redundancy in case of a fall or when rope gets damaged for some reason. Yet despite the two strands these two rope systems, i.e. half ropes vs. single with tag line, weigh about the same (single + tag = 75-100g/m vs. 2*half = 76-84g/m). In terms of weigh the only positive side with the single ropes is the fact that leader doesn’t have to carry the tag line. However in my opinion this advantage is diminished by higher rope drag, even on steep ice where you usually get to climb relatively straight lines. So based on above the only matter left to discuss is the impact force.
There’s been plenty of discussion about the impact forces. While on the surface half ropes seem to have lover impact forces, they’re actually measured with different standards. Tests with singles are being done by using 80kg weight, whereas half ropes are measured only with 55kg. For this reason some people claim that half ropes actually generate higher impact forces to the protection than single ropes. As there’s no comprehensive data on how half ropes perform as single ropes, one way to look into topic is to take a look at the ropes that conform both standards and then compare the results to ones that conform just one standard. Lets take a look at the specifications of multiple standards ropes first (the data is from www.tribevine.com, a climbing gear database that among other things has the specifications of several hundred ropes).
| Rope | Diameter | Weight | Single | Half |
| Millet Absolute Pro | 9.0mm | 54g/m | 7.8kN | 5.9kN |
| Beal Joker* | 9.1mm | 53g/m | 8.2kN | 6.0kN |
| Edelweiss Performance | 9.2mm | 53g/m | 8.2kN | 6.0kN |
| Bluwater Ropes Dominator | 9.4mm | 55g/m | 8.29kN | 6.61kN |
| Bluewater Ropes Hyalite | 9.4mm | 55g/m | 8.29kN | 6.61kN |
| Edelrid Sports Swift | 8.9mm | 52g/m | 8.8kN | 6.7kN |
| Mammut Serenity | 8.9mm | 52g/m | 9.5kN | 7.1kN |
Table above: Multipe standards ropes that conform both UIAA single and half specifications
So while this is manufacturer’s advertized specifications and definitely involve some creative rounding etc. there’s at least a one conclusion that can be made. Lower single impact force leads to lower half impact force and other way around. Based on above one could expect that a half rope that has lower impact force than the ones above, would also have lower impact force when measured as a single. Also the impact force ratio of single to half seems to be somewhere between 0.7-0.8. So lets take a look at some light half ropes, low impact force single ropes and compare them to the above multiple standards ropes then. For half ropes, I’ve calculated the single impact force values using the ratio above and shown in parenthesis.
| Rope | Diameter | Weight | Single | Half |
| Monster Ropes 9.2 | 9.2mm | 53g/m | 6.8kN | n/a |
| Beal Ice Line | 8.1mm | 42g/m | (6.1-7.0kN) | 4.9kN |
| Tendon Master 9.4 | 9.4mm | 58g/m | 7.0kN | n/a |
| DMM Climbing Prodigy | 10.0mm | 64g/m | 7.1kN | n/a |
| DMM Climbing Statement | 10.0mm | 66g/m | 7.1kN | n/a |
| Petzl Dragonfly | 8.2mm | 42g/m | (6.3-7.2kN) | 5.07kN |
| Tendon Ambition 10.0 | 10.0mm | 65g/m | 7.2kN | n/a |
| Petzl Zephyr | 10.3mm | 67g/m | 7.28kN | n/a |
| Beal Booster III* | 9.7mm | 63g/m | 7.3kN | n/a |
| Beal Tiger | 10.0mm | 63g/m | 7.3kN | n/a |
| Roca Migu 8 | 7.9mm | 41g/m | (6.5-7.4kN) | 5.2kN |
| Edelweiss Oxygen | 8.2mm | 42g/m | (6.5-7.4kN) | 5.2kN |
| C.A.M.P. Plekton | 8.2mm | 42g/m | (6.5-7.4kN) | 5.2kN |
| Beal Apollo II* | 11.0mm | 75g/m | 7.7kN | n/a |
| Millet Absolute Pro | 9.0mm | 54g/m | 7.8kN | 5.9kN |
| Tendon Ambition 7.9 | 7.9mm | 40g/m | (7.0-8.0kN) | 5.6kN |
| Sterling Rope Fusion Photon | 7.8mm | 41g/m | (7.0-8.0kN) | 5.6kN |
| Tendon Master 7.8 | 7.8mm | 38g/m | (7.1-8.1kN) | 5.7kN |
| Metolius Monster Ropes 7.8 | 7.8mm | 38g/m | (7.1-8.1kN) | 5.7kN |
| Singing Rock Gemini | 7.9mm | 39g/m | (7.1-8.1kN) | 5.7kN |
| Beal Joker* | 9.1mm | 53g/m | 8.2kN | 6.0kN |
| Edelweiss Performance | 9.2mm | 53g/m | 8.2kN | 6.0kN |
| Bluewater Ropes Dominator | 9.4mm | 55g/m | 8.29kN | 6.61kN |
| Bluewater Ropes Hyalite | 9.4mm | 55g/m | 8.29kN | 6.61kN |
| Millet Alpin Lite | 7.9mm | 41g/m | (7.3-8.3kN) | 5.8kN |
| Mammut Phoenix | 8.0mm | 41g/m | (7.5-8.6kN) | 6.0kN |
| Sterling Ropes Marathon Pro* | 10.1mm | 63g/m | 8.6kN | n/a |
| Sterling Ropes Marathon Mega* | 11.0mm | 79g/m | 8.7kN | n/a |
| Edelrid Sports Swift | 8.9mm | 52g/m | 8.8kN | 6.7kN |
| Edelrid Sports Apus | 7.8mm | 42g/m | (8.4-9.6kN) | 6.7kN |
| Mammut Serenity | 8.9mm | 52g/m | 9.5kN | 7.1kN |
Table above: Light half ropes, low impact force single ropes and ropes that conform the both UIAA standard compared against each other.
So following the line of reasoning of the first table, it would seem that at least quite a few half ropes should offer comparable impact forces when tested as a single. Furthermore while most of the multiple standards ropes are light, their impact forces are left behind most light half ropes.
The final thing to consider is how the lead fall differs from each other between the two systems. While a fall with a single rope is rather straight forward process, i.e. you always fall to the single strand, the issue is at least in theory somewhat complicated with the half ropes. With half ropes the number of strands that actively work while stopping the fall depends on distance to last piece of protection and rope stretch. In most cases half ropes act just like single ropes, i.e. one strand takes the wast majority of the force. In case of half ropes the rope stretch typically falls between 25% and 40%. If the average screw distance is about 6 meters, this means that you have to have at least two screws and 15 meters of rope out until second strand can even theoretically come into play. In other words you’re already well above the UIAA test case fall factors, i.e. the impact forces are a lot smaller. For this reason the way two strands interact doesn’t have relevance in normal climbing. However when leaving from the stance, where both strands are actually clipped through the anchor the issue is a bit different. There both strands work together and impact forces are a lot higher, worse still the fall factor is the worst possible. It seems that half ropes demonstrate impact forces in the range of 8-10kN in twin configuration.
Based on this, together with the other half ropes related benefits, at least my opinion is clear, half ropes is the way to go. However with half ropes it’s even more important to make sure you don’t fall against your stance. There’s a serious worst case scenario involved. This leaves also a difficult choice, weather to go with the lowest impact force half (Beal Ice Line) or the lightest one (Tendon Master 7.8 / Metolius Monster Ropes 7.8, basically a same rope manufactured by Lanex)? While 1kN difference in impact forces doesn’t feel dramatic it is probably larger in worst case twin configuration. On the other hand 500g / 10% difference (two strands, 70m long, 38g/m vs. 42g/m) doesn’t feel huge, but still considerable. Also the Tendon’s nano dry treatment is said to be great (though I don’t have much first hand experience, climbed just once with such rope)… …Right now Beal Ice Line feels a better bet. Funny enough I’ve been contemplating between these two ropes for some time now.
Oh, one final note; famous Will Gadd has an interesting article about the impact forces and comparing single ropes against halfs. They also actually did some real world tests, so a bit more scientific than my approximation approach. I have noted the ropes in the table that Will talked about with asterisk (*), with one exception for which I couldn’t find the specifications. From Will’s article it comes loud and clear that there’s plenty of variation as some difference compared to published figures. Despite these uncertainties, I’m still for half ropes for multi-pitch waterfall ice climbing.
My current ropes
Finally a few words of my current ropes and their uses.
Picture above: Rope endings with markings, I had to cut Joker due some nicks.
The web-stores that sell these things:
A few more images of my ropes:
6.7
Ice climbing, ropes and single vs. half,
I got the half rope ratings for the Serenity and Swift from their respective makers – they are in the table here: http://www.ukclimbing.com/gear/review.php?id=3765
I haven’t weighed the ropes I reviewed but perhaps should. Another test for a UK magazine found that actual weights bear very little similarity to manufacturers stated weights.
Thanks, will add those to my article as well. About the weights… Agree 100%, noticed it several times and been wondering why it is like that. Heard some rumors that it would be related someway to the way they’re measured. Don’t know for sure. If you have better knowledge, it would be appreciated.
Great article, by far the best I have seen!
Makes me to consider halfs, because rappelling down 2 ropes enables a pull-down with twice as much distance rappelled. Abandoned anchor gear is expensive!
Thanks Matti, it’s great to get positive feedback.
About the halfs … I truly believe in them especially on ice. On rock I’m not yet so sure, because the fact that durability seems to be a bigger issue … this being said, it seems that light single ropes, as Beal Joker aren’t very durable either (despite being extremely good rope, on rock you’ll whack it in no time – trust me, I know).