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Leading On One Rope Or Two?

Contributed to Chockstone by Robin, Owen & others and edited by Mike. See forum topic.

(Neither the contributors, nor Chockstone takes any responsibility for the accuracy of this article, or it's suitability for the purpose. Use at your own risk. Chockstone Photography | Landscape Photography Australia | Australian Landscape Photography

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So you're looking to replace your tatty old 10.5mm single 50m dynamic climbing rope and have been lured by the talk of old trad types climbing on two ropes? Perhaps you're sick of the rope drag your single rope creates on wandering routes and you know that drag is not just annoying, but also reduces your ropes dynamic properties, thus increasing fall factor. Maybe you're looking to go light and fast, and need two ropes to descend anyway. Whatever the reason, your eye has been caught by concept of leading up on two ropes rather than one. So now what? What are the pitfalls, the pros and cons?.... Read on.

Halves, Doubles, Twins   Push For The Summit

The first distinction to make is the difference between a "Half Rope" (also known as "Double Rope"), and a "Twin Rope". Half (or double) ropes generally have a little "(1/2)" symbol on them. With halves, generally speaking, as you lead up, you alternate clipping one rope or the other at least until the route starts to traverse or zigzag, then you need to plan clips to keep the ropes running straight as possible. So for example, you might lead up, put in a piece, clip blue, lead up a bit more, put in another piece, clip red, and so on. When you take a fall, you're caught by just one of the ropes.

Twin ropes, on the other hand, are generally marked with a little sideways "8", as in the mathematical symbol for infinity. The idea with twins is that you treat them like a single, and always clip both ropes through every piece. When you fall, you very much want to be caught by both ropes. For the purpose of this discussion, assume focus is regarding halves or doubles, and not twins.

Advantages Of Two Ropes   Push For The Summit

  • Reduced Rope DragReduce the dreaded rope drag (pictured right), which prevents your rope from acting as dynamically as it can. Bad drag can be very dangerous. You'll still need to extend runners to keep the ropes straight as possible and to avoid sharp edges & dislodging pro, but with two ropes you should have more options and require slightly less slings for extension.
  • You have a second rope should one be damaged by a sharp edge or cut by rock fall.
  • It's good for belaying up one second on both ropes involving a traverse, where-in the leader has clipped one of the two lead ropes during the traverse. Thus when the second arrives they'll have the other rope taut above them while cleaning gear and hopefully avoid any nasty pendulum falls.
  • As an alternative to the above, two ropes can be good for multi pitch climbing with three people where-in each second may be belayed up on one of the two lead lines, though this removes the aforementioned advantage. Just remember to protect any traverse section for the seconders on both ropes. See tips below. (It is also possible to belay two seconds simultaneously, though leave this trick to the experts).
  • Two ropes give you more options should you need to perform a cliff rescue. It would be possible to tie off one rope and use the second one as an abseil.
  • When pulling up slack to make a clip above waist height, the extra slack in the system will not increase the fall distance, as the other rope will still catch you.
  • Similarly if you have placed a piece above head height that you're not 100% confident in, you can do the move knowing that the slack introduced into the system if the piece fails will not lengthen your fall as the other rope will catch you, with the fall being no worse than it would have been had you not placed the suspect piece.
  • Double ropes are generally more stretchy than singles. The extra stretch in the ropes reduces the impact force a fall places on your protection, making suspect placements less likely to fail.
  • Having two ropes along rather than just one, means you can abseil twice as far.
  • Double ropes allows greater flexibility in load sharing for the horrible hikes into the better trad multi-pitch locations!

Disadvantages Of Two Ropes   Push For The Summit

  • Two ropes are difficult to manage and handle especially when the ropes are wet and you are on a hanging belay, the wind is howling a gale, and communication is near impossible.
  • Single 9mm ropes will tolerate less falls i.e. will need replacing more often, and will shear more easily than a fatter rope (in general).
  • Cost. Two ropes still costs more than one.
  • Difficult to belay. After clipping a higher runner one rope goes out while the other one comes in. If the climber is moving up then down, say at the crux, this adds to the difficulty of belaying. There is a considerable learning curve for both leader and belayer when moving to a duel rope system.
  • It assists the belayer if the climber calls the colour of the rope he/she is going to clip. Some of these calls can be mistaken for other similar sounding words. eg 'black' sounds like 'slack' and 'blue sounds like 'below'.
  • Beware abseiling off a single 9mm rope. A friend of mine nearly zippered off the top of Camels hump when rapping off one single slinky new 9mm rope. 
  • Also be aware some belay/abseil devices don't handle two ropes or skinny ropes (eg. GriGri).
  • When clipping runners it is easy to tangle the ropes up, for example by clipping out of order, and thus increase drag rather than avoid it. 
  • Care has to be taken to pull up the correct rope when clipping. Can be difficult if say clipping the right rope with the left hand in a tenuous situation.
  • Often you climb predominantly on one single 9mm rope against the manufacturers recommendations and if you do clip both ropes up a line you lose some of the benefits of using two ropes on a wandering route.
  • If climbing a multi-pitch route in a group of three (which is when double ropes really come into their own), and you want to swing leads, it is necessary to untie one rope from the leader and have the new leader tie in.
  • Two skinny ropes tend to get tangled quicker and worse than one single fat rope.
  • Two skinny ropes still weighs more than one single fat rope.
  • There is generally more stretch when falling on one rope of a pair of halves, thus increasing your distance fallen and chance of hitting something.

Tips For Leading On Two Ropes
   Push For The Summit

  • Call the colour of the rope that you are clipping so the belayer can feed out just that rope.
  • When the leader has clipped one high runner, feed out a small amount of slack on the opposite rope. This means that you can focus on belaying in the rope on which they are protected whilst the other rope is free to feed out.
  • Coil your ropes as neatly as possible and in separate piles when belaying up a seconder. Consider using a rope bucket (see feedback below).
  • If you're getting into climbing, and have a regular climbing partner, you can buy one double each to reduce the start-up cost.
  • Buy ropes of two colours that are easily distinguishable. Your climbing partner isn't colour blind by any chance?
  • Bear in mind that half ropes (doubles) are rated differently than single ropes. i.e. A single 10.5mm might be rated for falls based on an 80kg weight, while a single 9mm half rope might be based on a 55kg weight. This doesn't mean half ropes are less safe (quite the opposite), it's just a different system. 
  • For very short routes, you can get the same result by leading up on both ends of a single 50m rope.
  • When climbing as a group of three, if you choose to belay the second and third climber on one of the lead lines each, consider the issue of traverses. This is a difficult one, because it detracts from the main advantage of double ropes in this situation, which is that the second is protected from a severe pendulum fall by the other rope from above, if only one rope is clipped on a traverse that the leader finishes then climbs higher, (once beyond that point). It would be a judgement call by the party concerned with the circumstances at hand, how they deal with this. Possible solutions would be:
    1. Don't fall !
    2. If the traverse is short enough, have the second tie in mid-rope, and the third on the tail to gain the advantage of the overhead protection rope. (This assumes the second back-clips the rope when passing the pro).
    3. Place the most experienced climber last.
    4. If the traverse is really nasty the third person can belay the second from behind as well as having them belayed by the leader. (Another reason for putting the least experienced person in second place).

So One Rope Or Two?   Push For The Summit

Well that's going to depend on many of the things mentioned above as well as the terrain you intend to climb. Generally speaking a single fat rope is going to be fine for a simple day of cragging at most Victorian destinations, unless you're heading up wildly traversing or zigzaging routes. The two rope system is favoured by alpine trad climbers and mountaineers, however, it does have a place on some of the taller Victorian cliffs. Some people carry a second rope just to make long abseils, but still climb on one line. I guess the answer is, as always: it depends.

Reader's Feedback   Push For The Summit

"...The use of rope buckets will greatly assist the rope management issues. Ropes will never get tangled together. If rope buckets are used quite a few of the disadvantages become moot. You would see the whole article in a different light if you were to use rope buckets. Rope buckets are simply a bag that you stuff the rope into and the rope is then ready to be drawn out of on the next pitch." - Phil Box.

Chockstone Feedback - Discuss this article by leaving comments in an appropriate topic of the forum.

Further Reading:
What are twin ropes, double ropes, and half ropes and how do I use them - From Dawn's TradGirl FAQ.
Ropes and rope bags - Shows a definition of single, half and twin ropes from Time Outdoors.
Dynamic Ropes - Touches upon fall forces, half ropes, etc. From Blue Water.
Beal:choosing your rope - Shows a definition of single, half and twin ropes from Beal.
Climbing Rope Info Sheet - Overview of single, half, twins, etc.

Rope Systems - Single, Double, Twin methods explained From ABC Of Rock Climbing.


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