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Assembling and Adjusting Vertical (Frogging) Gear

by David Ochel

Pictures of Karen Masters and David Ochel taken by Robert Burnett

Petzl brand names (Croll, Omni, etc.) are copyright / trademark by Petzl


Having a well-adjusted set of vertical gear is key to efficiency on rope, contributes to safe caving, and provides for an overall greater enjoyment of vertical caving.  Maybe you have just bought your first set of frogging gear, or maybe you haven't used your kit in years - in this article I will provide some guidance on how to assemble and adjust it properly.

There are many philosophies of what an ideal and/or safe vertical kit is comprised of, and how to "fine-tune" it.  I am discussing my personal view here based on what I have learned from other cavers, literature, and experience, and you should feel free to take this with as many grains of salt as you would like, and use common sense in interpreting it.  This guide is primarily aimed at adjusting your gear for efficiency.  It is not meant to teach you all you need to know about safe caving techniques; the adequacy of particular knots for particular uses in particular situations; etc.  The author and publisher cannot accept any responsibility for you using any of these tips.  Seek out proper training, and know and accept the risks involved with vertical caving as well as the particular methods and mechanisms described here!

This write-up assumes that you have learned how to frog, and know how to use frogging gear.  I won't explain here what a cowstail is or what its purpose might be.  In general, it would seem to be a good idea to learn the basics from your local Grotto, maybe borrowing somebody else's gear who you trust, and having the opportunity to decide which type of descender you like, for example, before going and buying your own kit.  Your vertical kit is personal protective equipment.  If you are not intimately familiar with the terminology and practices of Single Rope Technique, for example with regard to the knots I am talking about, then have someone experienced help with or double-check your assembly before committing your life to relying on it.  Care ought to be taken when assembling a vertical kit from used parts as well – "software", like webbing and cord, as well as "hardware", like karabiners and ascenders, need to be inspected for wear and tear.

A typical frogging kit...

The components of your vertical gear should be pretty much the following:

  • seat harness and harness maillon ("D-Ring")
  • chest ascender and chest harness
  • upper ascender, safety tether, and foot loop
  • cowstails
  • descender

Some cavers use additional gear, like foot ascenders, and carry backup gear for emergencies.  We will focus on the essentials in this article.


Fresh ingredients" for a set of vertical gear - click for a larger image

Fresh ingredients" for a set of vertical gear.

Here's what my shopping list would look like for a basic frogging kit.  You might want to read on first, poll others for opinions, and then decide on what exactly you want to buy:

  • Hardware
    • a chest ascender
    • an upper ascender (I use one with a handle)
    • a D-Ring (Petzl Omnis with a screw-lock are my favorite)
    • a maillon, also known as screw link, to attach the upper ascender to its safety tether (I use a 5 mm); do not buy those from hardware stores, since they aren't rated/tested for personal protection
    • a descender (choices here vary broadly, but you will likely want a "caving" descender rather than a rock climbing-style ATC or some such)
    • a (fairly large – 7mm, 10 mm?) maillon, or a screw-lock karabiner, to attach your descender to the D-Ring
    • two straight-gate, non-locking, asymmetrical karabiners with key-lock gates
  • Software
    • a caving seat harness
    • a chest harness
    • about 4 meters (12 feet) of 9.5 mm (9, 10, whatever) dynamic rope – check with the caving vendors, stores like REI don't typically sell dynamic rope by the foot; this is for making cowstails and a safety tether
    • a foot loop (I like the adjustable Petzl ones, or you could make your own from accessory cord, webbing, and/or various other ingredients.

...and how to adjust it

Caving harnesses have a lower point of attachment than rock climbing harnesses, because you sit in them a lot, and because more distance between your chest ascender and your upper ascender allows for more efficiency while climbing.  (As opposed to just using them as a safety to protect against a fall, and maybe rappel on them every now and then.)  Caving in a rock climbing harness is not necessarily unsafe; it's just extremely inefficient.

The tail of the webbing that is threaded from left to right through the buckle is threaded back through the buckle again - click for a larger image.

The tail of the webbing that is threaded from left to right through the buckle is threaded back through the buckle again.

On a typical caving harness, you want to adjust your belt strap and the two leg loops so that the harness sits tight, but not necessarily uncomfortable.  If your harness buckles require it, make sure that they are all double-backed, i.e., the loose end of the webbing is threaded back through the buckle to prevent slippage.

To close the harness, use a half-moon shaped D-Ring.  Not a regular karabiner, tri-link, or anything else.  Since you will attach more than one piece of life-supporting gear to this link, and loads might shift from one piece of gear to another in a split second, it should be designed to withstand significant loads in multiple directions.  The D-Ring connects the two open end loops (or links) of your harness with each other, with the bent side of the D-Ring pointing up.  You will want to attach any and all vertical gear that you are using to the half-moon-shaped side of your D-Ring between the harness loops.  Don't accidentally rappel off the descender that is still attached to the gear loop of your harness.

Your D-Ring, be it an aluminum or steel maillon, or a Petzl Omni karabiner, will have a screw link or gate, or maybe a quick lock.  Either way, pay attention to the direction it screws shut.  When you are climbing on your ascenders, the rope leaves your chest ascender in the vicinity of that screw link.  Under unfortunate circumstances, the rope might actually rub against the screw link, and contribute to screwing it open or shut – depending on which way you have put on your D-Ring.  You don't want to unlock your D-Ring accidentally while you are on rope.

Chest ascender and seat harness

The chest ascender goes on first, its backside sitting flat against the belly - click for a larger image

The chest ascender goes on first, its backside sitting flat against the belly.

There is not much to adjust here, depending on which chest harness you use.  There is a - quite obvious - way to put your chest ascender on your D-Ring:  The flat part against the belly, and the cam facing outwards.

How tight you want your chest harness to be depends a lot on personal preference, but pay attention to how things work when on rope.  Your chest harness is supposed to keep your upper body close to the rope when climbing, and (to a certain extent) to keep your chest ascender upright.  That won't work if the chest harness is too loose.  I prefer a chest harness that I can cinch down quite a bit when climbing, and release to a more relaxed fit while off rope.

Upper ascender, safety tether, and foot loop

Part of a frog system is an upper ascender (often referred to as a handheld ascender, regardless of whether it has a handle or not), and a foot loop.  Technically, you could climb without tethering that ascender to your D-Ring.  Which would be a bad idea, because you wouldn't have a second piece of attachment to the rope while climbing.  So, we need a safety (tether) to attach the upper ascender to the D-Ring.  I have a dedicated safety, others just use their long cowstail.  I tried that approach for a while, and eventually decided that I prefer to have both of my cowstails available while using my ascenders.  (Anyway, if you use your long cowstail as the safety for your upper ascender, you might want to use a locking 'biner for it.)

An overhand knot on a bight - click for a larger image.

An overhand knot on a bight.

The way I attach my safety to the D-Ring is by means of an overhand knot on a bight.  That knot doesn't slip, so I can slide it on and off my D-Ring conveniently.  I keep the bight as small as possible to prevent unnecessary clutter around my D-Ring, and an inch or two of tail on it.  Some technocrats may look negatively upon an overhand knot used as a life safety knot.  A less debated knot would be a figure eight on a bight, which is a little bulkier.  More options exist.  I can't make that decision for you.  Regardless, always keep an appropriate amount of tail.

I attach my upper ascender to the safety using a small maillon.  You could tie it directly into your upper ascender, or into a locking karabiner that also connects your foot loop, or something else that is rated to personal protective equipment standards.  For this, I use what I've heard people call a barrel knot, which is half of a double fisherman's knot.  It tightens nicely once weighted, doesn't get in the way much, and - handy for cowstails in particular - if you hold the knot in your hand, the piece of gear attached to it won't wobble around.  I've heard somebody say that there have been accidents attributed to this knot being used for this purpose, and I've learned from others that they are designed to flip over when they are shock-loaded.  So, I keep at least a fistful of tail on that knot.

The length of your safety should allow you to move your upper ascender up high enough so that you can make efficient steps when climbing, but short enough that you can reach the upper ascender when you hang from it in an emergency. I adjust mine so that I can actually grab the rope just above the upper ascender while hanging from it on rope, or, comfortably, the upper ascender itself.  For that to work, you need to hang from your upper ascender on the rope, without using your chest ascender to sit in it, and without your feet touching the ground.  This adjustment typically takes me multiple iterations of knot tying and getting back on rope until I get the length right, in particular because the barrel knot - which you should bounce on for a few times while you hang from it, in order to tighten it - will give a bunch of rope as a result.

A "quick and dirty" way to adjust the foot loop - click for a larger image

A "quick and dirty" way to adjust the foot loop - stand in it and adjust it so that the cam of the handheld ascender is just above the cam of the chest ascender.

A "quick and dirty" way to adjust the length of your foot loop to something useful is to stand in it, on the ground, while it is attached to your upper ascender.  The cam of your upper ascender should be just above the cam of your chest ascender when you pull the foot loop straight up.

To fine-tune the length of your foot loop, you may want to get on rope and make a few frogging steps.  When you stand up in the foot loop and lock your legs, the upper and chest ascenders should be as close to each other as possible without actually interfering with or touching each other.


Cowstails come in handy in many situations, some of them requiring a slightly longer and some of them a slightly shorter length.  The actual length seems to be personal preference to a certain extent.  Some folks are perfectly happy with the pre-sewn webbing cowstails sold by Petzl at their standard length.

I make my cowstails from dynamic (climbing) rope.  Whether it makes a difference that your cowstails are made from a dynamic piece of rope, webbing, or a (relatively) static piece of accessory cord when you catch a fall on it to a certain extent seems to be a philosophical debate, and my personal philosophy is that I'd rather take a factor-2 fall on dynamic rope with a relatively large (9-10 mm) diameter.  Your mileage may vary, but I've seen reports of tests that have suggested that dynamic rope is in fact the most appropriate for the job.

Cowstail lenghts - click for a larger image

Cowstail lenghts.

I make my short and long cowstail from one piece of rope, not two separate ones, in order to reduce the amount of knots that go onto my D-Ring.  For the knot on the D-Ring I use, again, an overhand on a bight.  A butterfly knot is a good alternative here.  The 'biners at the end of my cowstails are attached with barrel knots.  (See instructions on the safety tether above about tightening them.)  But how long should the cowstails be?

Stand upright, wearing your harness and having the cowstail attached to your D-Ring. When you extend your long cowstail at a 90 degree angle from your body, and extend your locked arm (keep your body upright), your 'biner (or the knot attaching your 'biner to the cowstail) should lie in your hand.  For the short cowstail, bend your arm and put your elbow against your belly.  Again, extend the short cowstail at a right angle, and you should be holding the end of it in your hand.

My cowstails don't match that advice exactly, over the years I have slightly adjusted them to what I currently think is my "perfect" length.  But anyway, above advice seems an excellent starting point.

A word on which karabiners to use: Unless you have a good reason not to, use straight-gate, non-locking, asymmetric 'biners.  Tests have shown that in some twisty, tangled up situations, rope will be able to accidentally unclip itself from bent-gate karabiners easier than it could from straight-gate ones. Using 'biners with "key lock" gates is also recommended, as they are less likely to get hung up when unclipping from anchors and rope.


There is nothing to adjust here, r eally. I use a fairly large maillon to attach my descender to my D-Ring. Others use locking 'biners, which has reportedly lead to accidents in a few cases where they became unlocked while on rope.  Some racks have an eye that can be threaded directly onto the D-Ring, depending on the angle you'd like your rack to be twisted at while in use.  Whatever you use, keep it short, i.e., keep the descender close to the D-Ring, in order to minimize hassle when changing over from climbing to rappelling.

Putting it all Together

The order in which to put your chest ascender, safety, descender, and cowstails on the D-Ring seems to be subject to philosophical debate, as well.  Here is what I do:

Keeping the advice on rope-rub above in mind leads me to attach my D-Ring first to my right harness loop, with the open gate on the left-hand side when looking down at it.  First (i.e., all the way to the right) goes my chest ascender, so that none of my other gear on the D-Ring will be able to interfere with the open cam of it.  Next on goes my descender, followed by the safety for the upper ascender.  All the way to the left, before closing the harness by putting the other harness loop on the D-Ring, go my cowstails.


A word on inspecting your vertical gear.  You will want to take a close look at it every so often.  Hardware can be damaged if it is mistreated or takes long falls, and software tends to wear out, in particular where it rubs against other parts of your gear.  So, check you harness webbing for fraying regularly, in particular also the insides of the loops for closing the harness with a D-Ring if they are made of webbing.  Cowstails and upper safety are among the pieces of my vertical gear that I replace most frequently - when you inspect them, also pay attention to all aspects of their knots.


Thanks go to DJ Walker for reviewing this manuscript and providing valuable feedback!

Feedback and questions

Feedback and questions are welcome. Send an email to do@ochel.net.

A good forum to discuss vertical caving techniques and gear is the NSS's Cavechat forum at


If I were to buy only one book about caving techniques, I'd buy this one:

Marbach, Tourte. Alpine Caving Techniques. (English Edition.) Allschwil, 2002.