A Teton rappel. On this particular day I used the Grivel Scream with a Sterling V-TX 5.4mm rope. Thankfully we had enough rope to avoid a single stranded rappel here. Photo: Adam Fabrikant
As high tech, skinny ropes continue to grow in popularity throughout the ski touring world, I often wonder how many users are having close calls or scary experiences rappelling on these ropes. In many ways, rappelling on a 6mm-ish rope is similar or the same process as rappelling on a regular climbing rope—but when it comes to adding friction, the skinny ropes require some practice, personal testing, and expertise.
When we think of rappelling techniques, the most basic requirement is adding sufficient friction to descend the rope in a controlled manner but not so much friction that we can’t descend easily. The original, and most basic friction device is your body, as exemplified by the Dülfersitz or an arm rappel (wrapping the rope around your wrists/forearms and across your back). Fortunately, for our comfort and safety, brands have progressed to various friction devices designed for belaying and rappelling. The most ubiquitous modern devices are tube styles like an ATC, or Petzl Reverso—these devices simply attach the climber to the rope while introducing a sufficient amount of friction for a controlled descent.
Duelfersitz Rappel, no gear needed. Photo: Wulf Alex Link to copyright
When it comes to skinny ropes around 6mm, you will quickly realize that a standard ATC or Reverso does not provide nearly enough friction for a controlled descent, and often makes for a disconcerting or downright dangerous rappelling experience. While there are ways to make these devices work (stay tuned), there is a growing supply of devices made with these skinny ropes in mind—we will cover many of these options below.
Rappel devices in question from the top left going clockwise: Grivel Scream, Edelrid Mago 8, BD ATC Alpine Guide, Edelrid MicroJul.
For several reasons, I set up each device with an extension and a “third-hand” backup. This setup is worthy of its own post, but in brief, the extension helps add friction, allows for a full-strength backup off the belay loop, and allows me to go hands-free to untangle ropes or check anchors. I’ve been using a 110cm Blue Ice alpine runner as a tether and extension, or if I’m doing many rappels or in a group larger than two, I bring a Petzl Connect to adjust for added tether adjustability.
My current preferred tether/extension setup—using a 110cm Blue Ice alpine runner. Easy to untie, robust, and sleek.
Devices
BD ATC Alpine Guide
This is a great starting point for most people with most ropes. The ATC Alpine works like a standard ATC style device, so it requires minimal adjustment from a full-size device to work pretty well with skinny ropes. The recommended range is 6.9-8.5mm, so 6mm ropes fall outside the recommended range. That noted, as a double rope rappel with the Beal Backup line, the friction is sufficient with most carabiners. With some tomfoolery (see the Reverso section below), sufficient friction can be achieved with slick ropes or a single strand. Still, in a standard setup, a single strand rappel on any of the common skinny lines is a terrible option.
Standard setup of the Black Diamond ATC Alpine Guide.
The shrunken slots on the ATC Alpine Guide provide significantly better friction with small ropes.
BD ATC Alpine Guide - 74.1g
Grivel Scream
This is a mini version of a plate style device like the Kong GiGi. While it is one of few devices explicitly recommended for sub 6mm ropes, the plate design is generally suboptimal for rappelling. It requires an extra carabiner compared to the other options, and the setup is a bit more complex and easier to get wrong relative to an ATC style device. I was excited about the Scream when it first came out, but I rarely reach for it these days. A few orientations are possible with the Scream, although the friction adjustments they provide are minimal. Every rappel I’ve done on the Scream leaves a small collection of rope sheath along the slots in the device, which can’t be good for rope longevity. Overall, While I appreciate Grivel making a device for these ropes, I’m not sure the plate style is ideal for this application. Recommended for 5-8mm ropes.
Grivel Scream in what I believe is the highest friction setup. Needing two carabiners feels heavy and clunky in this context.
The other side of the Grivel Scream, note how the rope runs over the orange carabiner - careful of burrs on the gate pin!
Grivel Scream, 44.1g. Requires two locking carabiners for normal use so add ~40g.
Edelrid Micro Jul
The Micro Jul seemed like an amazing device when I first found/purchased it 5-6 years ago. Fast forward, and it’s been 5-6 years since it left my gear closet. It’s a bit confusing to use; the auto-locking mode seems like a great idea, but feeding rope on low-angle rappels is often challenging. Flipping the device such that the rope feeds in from the back is possible, effectively eliminating the auto lock function. This orientation leaves you without a functional wire loop for loss prevention. Overall, I just haven’t found this thing better than an ATC alpine in any of the day to day tasks of winter ski mountaineering/rappelling. Recommended for 6.9-8.9mm ropes.
Edelrid Micro Jul, note that in a normal context, a third hand isn't necessary as the Micro Jul auto locks quite well.
The Edelrid MicroJul. Note the thumb loop, camming this loop upwards opens the device to allow descent. This can be quite a bicep workout on a low angle rappel.
Edelrid MicroJul - 62.1g. The body of the device is steel, so if you like to use the device, it'll last you a while. Mine will last an eternity given my distaste for it.
Edelrid Mago 8
I just bought myself a Mago 8, so these impressions are gleaned from yard fooling rather than the “real” world. That said, this little device has a ton going on and seems to meet all the eventualities/possible needs for ski mountaineering in the lower 48. It has many friction options for rappelling—it seems likely that it would be possible to add enough friction for a single strand of 6mm cord. The Mago also has a belay plate functionality for bringing up a second or rappelling in plate mode, similar to the Grivel Scream. In my off-the-deck tests, it was easy to add/subtract wraps on the “horns” to increase/decrease friction. I got good friction/control on a single strand of Petzl Pur’line, the slipperiest of the ropes I own. Adding to my excitement with this device, it only requires one carabiner, and the rope doesn’t run through the said carabiner, so a superlight locker such as the Grivel Plume is the obvious choice. Recommended for 6-9.5mm ropes.
The "standard" setup of the Edelrid Mago 8.
Edelrid Mago 8 with an additional wrap for added friction with a slick single strand of Petzl Pur'line.
Edelrid Mago 8, 38.2g. Keep in mind, one can use a single, superlight locking carabiner with this device as well.
Petzl Reverso Hacks
Maybe skinny rope rappels are an infrequent activity, or you just don’t want to own another piece of equipment for this specific task (I can’t relate). A good old fashioned Reverso (or BD ATC, DMM Pivot, etc.) can be “hacked” to provide suitable friction with many skinny ropes in a two strand rappel. There are many ways people have rigged this over the years, some better than others. Here are a few we like:
A clever and high friction Reverso threading method I picked up from Mark Smiley. Both ropes in both slots!
Another view of the "both ropes both slots" method, I would worry a bit about odd wear patterns on the middle rib of the device if I was using this all the time.
Two ropes in one slot on the Petzl Reverso, a handy trick.
A snug fit makes for good friction.
Conclusion
I’m not sure the perfect device for these applications exists yet. For most circumstances, the ATC Alpine or Mago 8 seem to make a lot of sense, but the ATC Alpine falls short in the case of a single strand rappel on many of these ropes—which I view as a worst case scenario as far as rappelling friction/security, but also a possible necessity in a pinch.
Perhaps, the perfect device was out there in the form of the Petzl Reversino, a discontinued mini device that many folks have hoarded and swear by. We will explore rope options, different tether/extension setups and more as we delve into the nuance of these systems. Let us know if there are any devices or tricks we are missing, or other lessons to share on the topic of rappelling on skinny ropes.
Is there a place that shows the different rap configurations for the mago 8? Petzl has some nice diagrams for the pirana, but it looks like the mago is threaded a little differently, and edelrid doesn’t seem to post the manual online.
Yes, it’s in the manual, however it is a link to download it, the link is on the Mago 8 webpage, lower left.
Weird way to do it, took me a while to find it there too.
The manual is available under the “downloads” tab on the Mago 8 Webpage. Edelrid shows three recommended configurations, the photos above show the fastest and slowest options.
What are your thoughts on just rapping with a super munter on skinny lines?
Stay tuned Jonathan: I’ll try to get a text thread from Adam/Billy/Gavin organized for a response. Thanks for reading.
Hey Jonathan—just posted a story replying to your question. Thanks for that.
Spitballing a bit. I may be making this up, but I believe there’s a general recommendation that third hands are more effective if they are a different diameter from your rope. Have you experimented with using super tiny cord as a third hand? Obviously that’s a lot less surface area to create friction, but maybe a small enough diameter would just clamp down on the rope tightly enough to work? Could relying on tiny cord to really clamp down on the rope be an effective solution for more slippery ropes like the pur line? Would it potentially be effective at breaking through ice on ropes?
My follow up question would be, even if effective, is there a risk that tiny enough cord would damage the rope if too much force was applied? (I think you mentioned using a flat sling for a third hand on the podcast, so I was just wondering if going down in diameter rather than up could also be effective).
I don’t have any real small diameter cord at home so haven’t done any full testing or bodyweight yet, but i just threw a shoelace on pur line and it might have potential? Prusik/kleimheist were solid as hard as I could pull (which admittedly may not be super hard), 3 loop autoblock was useless, 6 loops felt solid.
Just a follow up, did some testing on this with promising results. Small diameter cord actually seems to work quite well, with the caveat that you have to do it right for it to work. Somewhat of a dumb caveat, as that’s true for everything, but I feel like it’s more finnicky than a hollowblock on a climbing rope. If you do too few autoblock wraps, it’s not just low friction mode, it’s utterly useless zero friction mode. And if you position the third hand too high (more on that later), you completely lock up and cannot release the hitch under tension.
I purchased some 2.5 mm Marlow D12 Max 99 and tested on a 6mm PUR line. So basically the slipperiest setup you can get – dyneema on dyneema. I went with the dyneema line because, despite it being slippery, heat-sensitive, etc., the average non-dyneema 2.5mm cord is only rated for about 1kn. The marlow cord is rated to 12 kn, 11 kn spliced. SK99 is stronger (but more expensive) than the amsteel cord, which I believe is SK75 or 78. I just knotted it for some quick testing purposes. This can reduce strength up to 75% on these dyneema lines, so some caution is warranted. Splicing, on the other hand, would roughly double the diameter of the cord where the ends are buried, kind of negating the original idea – that a smaller diameter third hand would be effective on these 5-6mm ropes. I am interested in getting some of the 4mm line, rated to 30 kn, and seeing how that performs as a third hand – no real strength concerns with knotting a 30kn line. Here is the spec sheet for the cord: https://shop.marlowropes.com/content/files/datasheets/defence/d12%20max%2099.pdf
I tested both single and double strand raps off the garage rafters. I have not done any bounce or tiny fall testing yet, as I didn’t want to tear down the rafters. I did do some ‘let go of the rope’ testing though. I found that 4 autoblock wraps was sufficient for a solid third hand, even on a single strand. It worked very well as an emergency brake. Letting go of the rope resulted in a rapid but not overly jarring catch. Going hands free was solid as well, I just sat around with no slippage if I used 4 wraps. With 3 wraps, there was extremely slow slippage, like a 1mm/sec sort of thing – it still worked as an emergency brake, but would not be effective for going hands free to deal with rope tangles, etc.
A sufficient number of wraps is really important – 2 wraps was a complete change – no friction whatsoever, might as well have not had the third hand on. Combined with the fact that it’s not exactly easy to control these thin lines on rappel, it’s not something you want to goof up.
I also found that it is extremely important to keep the third hand at your waist level – if the third hand was allowed to ride up higher towards the extended belay device and sort of pre-tighten a bit before tensioning, it completely jammed up and became unreleasable upon tensioning. Just completely stuck in place mid-rap. I think this is in part due to small diameter tightening up on itself very well, combined with the fact that it’s so small you have very little real estate to press down on when attempting to release a jammed up third hand.
The jamming was so extreme that it may be worth having a double length on you for overhanging rappels so you have a way to create a foot loop and release tension on the third hand in the event you let it ride up and jam. (Obviously this raises some questions about whether you are actually saving weight if you’re bringing an extra sling – but as far as finding a third hand that can provide some confidence that it’ll consistently lock on skinny, slippery ropes, I am hopeful that this will fit the bill – this is just an initial round of garage testing so more is needed to ensure real confidence).
I have not tested completely overdoing the number of wraps, but would be concerned about this jamming up and becoming unreleasable as well.
I am also concerned about how this would interact with ice buildup – could the third hand get stuck above some ice and jam up that way as well?
Abrasion of the third hand is also a potential concern. The cord has already dulled in color quite a bit – I am not entirely sure whether this is actually abrasion to the cord itself or just the “armour coat” Marlow applies wearing off. There has also been a tiny bit of fraying/fluffing over about an hour of sliding up and down the rope. Something to keep a close eye on, especially given how thin the cord is.
Heat buildup is also a concern with dyneema given that it experiences permanent, significant strength reduction at a much lower temp than nylon. However, a PUR line is dyneema as well, so the same heat concerns exist with the rope itself. If you’re using a PUR line, it seems hard to write off a dyneema third hand just for heat related concerns. This article does not address rope on rope heat buildup, but does seem to provide some relevant info about heat buildup on dyneema when rappeling: https://www.blackdiamondequipment.com/en_EU/stories/experience-story-qc-lab-can-a-hot-belay-device-melt-my-rappel-slings/.
(As an aside, I found the third hand worked so smoothly when done right that I could do a two finger rappel, just pinching the top of the third hand to very consistently lower at a pleasant pace. But as a practical matter, the heat buildup and abrasion concerns probably make this more of a novelty than an actual strategy on rappel).
Anyways, there at least seems to be some potential, worth continuing to mess around with, I’m sure there are more nuances and issues to discover. Hope the info is useful.
Ben,
That is something I have wondered about too. When I learned to climb (25 years ago) single ropes were going from 11 to 10mm, and we were (still) taught that a friction hitch should be about half the diameter of the rope it was going on. This has always concerned me with modern skinny ropes .
With the set up you are describing, I would really worry about the sensitivity to height you mention. After all, depending how you start your rappel, as you move around, stretch, bend over and load the rappel device, I certainly don’t always have my third hand in exactly the same place.
Yeah I think that issue really emphasized the importance of having comfortable one-handed control of the rappel and using this type of third hand as a true backup, not as an assisted braking device to help control a skinny rope. With comfortable one-handed control it was easy to use my other hand to keep the third hand from riding up. I ordered a mago 8 to see if that fits the bill for one-handed control on a single strand.
But this may just not be the best option for a third hand if it’s too sensitive to jamming. I haven’t tried the flat sling previously mentioned for comparison yet.
Thanks for the detailed reply, Ben! I’ve done some thinking on this and am working on what could be a decent solution. A couple thoughts here:
– knotting dyneema – I think the splice is worthwhile, as I’m sure you saw, knots don’t like to stay put in amsteel. There is a HowNot2 video on youtube that shows pull testing of knotted dyneema – not pretty.
– heat buildup is significantly more concerning to me in a third hand compared to a rappel line. Because we are moving down the rope, the heat buildup is dispersed along the length, with the third hand, it is subject to all of the heat buildup in a static manner.
– I wouldnt worry about the color wearing off- the dyneema seems to not “take” color well and it wears off quickly while splicing or working with dyneema
I did some testing with the braided aramid core of some tech cord I had around – it is 4mm or so in diameter but has an extremely loose weave. Problematic for snags and keeping a splice tight, but I had similarly excellent results. I also found myself on the Marlow site, and just ordered some 3mm V12 line, which is Vectran (Aramid) and shouldn’t have issues with heat buildup. More to come!
I was reflecting a bit on how to splice a third hand loop without doubling(ish) the diameter of much of the cord with the buried tails. A simple spliced loop does not seem to meet this goal. I’m just learning about all this splicing stuff, so there may be a much better solution that I’m blissfully unaware of, but perhaps an overhand knot soft shackle that you don’t actually shackle could fit the bill? (Could just leave out the eyelet that would normally slip over the knot). This would seem to have the benefit of allowing you to (mostly) hide the buried tails in the knot itself, leaving most of the loop at the diameter you want. An overhand soft shackle knot appears to simply tighten on itself with use rather than rolling or slipping (and appears to do a better job avoiding the more dramatic strength reduction concerns typically attributed to knots in dyneema). That being said, I do not know if a third hand configuration (clipping a carabiner at the knot and at the other end of the loop) would maintain the strength benefits of the soft shackle. (The third hand would arguably be sort of a triple/quadruple wrapped soft shackle connected via a carabiner rather than an eyelet around the knot, but the stress is probably being placed much more unevenly at the connection points than an evenly stressed soft shackle? And the stress is being applied differently at the knot.) Just some more brainstorming. Looking forward to hearing about the V12 results, that does seem like a much more appropriate material.
Alright my replies are glitching out for some reason so just trying the comment box.
Slim – I felt like the height sensitivity issue really emphasized the importance of having comfortable one-handed control of the rappel and using this type of third hand as a true backup, not as an assisted braking device to help control a skinny rope. With comfortable one-handed control I felt it was pretty easy to use my other hand to keep the third hand from riding up. So maybe that’s enough to alleviate issues with jamming up? I ordered a mago 8 to see if that fits the bill for one-handed control on a single strand.
Gavin – Awesome, I didn’t know about the V12 cord, that definitely sounds better. Look forward to hearing how it works. And correction well taken about heat being a bigger concern with a third hand consistently subjected to friction.
I somewhat surprisingly found that the overhand w/ a backup overhand is quite solid, at least for the 2.5mm. Initial impressions don’t seem to present any concerns about it untying itself, though it’s still not terribly hard to untie purposefully. But that of course doesn’t remedy the strength loss concerns. I probably should have said more explicitly, I would not be comfortable using the knotted 2.5mm cord outside of garage testing. But I’m not sure what the best way to splice is.
Using the Marlow recommended 50x diameter buried tail, by the time you’ve buried two tails in a continuous loop ten inches of your loop is pushing 5mm instead of 2.5. Maybe an eye splice would work, as you’d have a tail hanging off but your entire loop would be the diameter you selected. I do wonder if a carabiner wiggling around in the notch of an eye splice could loosen the splice though. Not sure if stitching the splice would be enough to alleviate that concern?
https://www.ropelitellc.com/product-page/micro-prussik
Heard about these on the sharp end podcast
This is really interesting – just from looking at the site, it seems to solve the issue of the splice taking up too much of the loop with a splice of his own design (snake splice?) and stitching the splice? Ordered one for comparison. I’m also interested in how the 5mm cord he describes as grippy compares to a slippery smaller diameter cord.
Testing update – all in all, some positive results on the Ropelite Micro Prussik. He reports on his website that the 5mm cord holds as an autoblock on the edelrid rap line, mammut glacier cord, and 6mm accessory cord. I tested with a PUR line, for a sort of “slipperiest possible scenario”. This 5mm cord does NOT hold as an autoblock on a PUR line, even with added friction from a rappel device. This failure may also say something about how well the cord will hold on the above lines if they are wet or icy. So user beware. Diameter seems to be king in terms of factors affecting holding power. HOWEVER, it held very nicely as a kleimheist. I found that a four wrap kleimheist held well as a rappel backup (used mago 8, friction mode 3/3+), and that a five wrap kleimheist held my full weight on a single strand of PUR line (with no rap device in the system).
This is just some initial garage testing, but I’m quite happy with it so far. It’s not that much more time consuming to do a kleimheist than an autoblock, and it is much easier to handle/not drop the 5mm cord than the little 2.5mm cord I was playing with. It was also easier to release tension/friction on the 5mm cord (more to grab on to and push down on), and I did not encounter any issues with jamming. The FAQ section on the website has some comments about the heat resistance of the polyester material. I can at least say it’s worth checking out if you’re interested.