An interesting question was raised yesterday:

"Why do we climb trad with 2x half rope?"

1) It is not redundancy:
- You fall on one rope anyway.

2) It is not gear impact-loading:
- Trad is done in the USA on 1x sport rope.

3) Many other factors are relevant such as
- weight,
- possible abseil length,

But what is there real, technical reason?

To keep your rope running in a straight-ish line when protection is not in a straight line, so it doesn't yank gear sideways, and out, when loaded. They only climb with one rope when the line is pretty straight, like Utah cracks & such.

So then why not climb with 2 x single ropes?



Half ropes can take a fall like a single rope.

Then why not climb straight Utah cracks with 1x half rope to save weight?

Hi

Proze is right, the reduction in rope drag plays a significant role in using half ropes over a single rope and is probably the best reason to do so.



True, but should that one rope fail (or all the gear on it fail), you do have a second rope that may keep you from decking.



You are correct that they trad on single ropes in the USA but incorrect about the impact loading: it does reduce impact loading on gear if you use half ropes because they are more stretchy than single ropes. So for routes with marginal gear it would be better to use half ropes.

_________________
Happy climbing
Nic

I disagree:
Often, should you fall on the first couple of placements, and one rope fails, you will deck before the second rope catches you.
So no, I don't think redundancy has much to do with it.
Especially if you do TM type climbing.
Them BEEEG mountains in Pakistan and India may be different though.


So why not climb on 1x half rope only in the USA?
Redundancy? I don't buy it...... (but have been wrong once before )

About the redundancy: I've taken a fall on Spout and ripped gear on both ropes. 1 right, 2 left, caught by dodgy equalised pieces on the left rope. Next up was a bomber cam on the right rope. I was still far enough off the deck for the cam to have caught me. So I think there's something to say for redundancy.

Why not climb on a single half rope? Because half ropes don't last as long as singles.

Other reasons for 2 half ropes. You can have 2 seconds. Sure you can climb on 2 singles, but you'll have a hard time finding partners willing to carry the ropes. Even the increased drag from singles is a drag.

What Paul said about keeping it straight, it makes a big difference, especially when it comes to the dreaded reverse zipper.

Rap a rope length. You're stuffed with 1 single.

Sometimes it helps when you make a dodgy clip to know you're not going to fall on the rope with all the slack in your hand if you come off now.

The most important reason is you can't climb with 1 half rope, because you'll only have half of what you need. Obviously you also can't climb with 2 singles then, because you'll have double what you need

See, the longer I think about this, the more I lean to agree with you here shorti.

I cant really see any major advantage of climbing with 2 half ropes rather than 2 single ropes.

You can lead on a single half rope - it's just scary. Climbing cracks in Yosemite I was really happy to have a beefy single rope - it just felt so much safer near those sharp flakes than having a skinny rope. Someone braver might feel differently. We used half ropes effectively on some routes there too - more efficiently I think than US locals doing the same routes on singles. Single ropes have other uses - you can short fix easily with them. Our rock doesn't lend itself to this, but it makes a lot of sense on long crack climbs or on aid routes. It's also way easier simulclimbing on a single with a grigri at each end, than on half ropes. You can jug a single rope, which you can't on a half. On the Nose we climbed with two singles for this reason and it worked well. Half ropes have nice advantages though. You can climb very efficiently as a party of three. If you do it right it can be faster than climbing as a pair and is almost always more fun. If you're doing a long route the second can haul the daybag on one rope while following on the other. This is also very efficient if done right. I way prefer half ropes on routes where the gear is dodgy - the lower impact force is reassuring as well as knowing that if the first piece fails there is a lower shock load on the second piece on the other rope. At a crux move its nice to put gear out wide to the left and to the right. If you come off you get a nice cushy fall in between with half the impact force on each piece. Half ropes let you abseil further. There is no "right" system. The more techniques you know the more you can choose the best solution for a particular climb. I've found half ropes are the best compromise for almost all our local crags. They're just more flexible. In SA I will only take a single rope to a very specific route where I know I need special tactics to succeed. I have seen a US dude try do Red Corner in one pitch on a single rope (something we regularly do on half ropes). He was forced to take massive runouts and he still had tons of rope drag by the end. It was not pretty on what was, for him, an easy climb. Hans Florine has a great book called Speed Climbing where he describes a bunch of tricks for moving faster. The overwhelming impression from the book is that you should take the gear that will allow you to be the most efficient. That should always be the goal when selecting a rack, ropes, a pack, a sleeping bag, shoes or anything else. Its equally applicable for onsighting single pitch routes to doing walls or alpine missions.

So do you consider the less impact force on the gear as not worth mentioning then?

- Half ropes are designed to have similar impact forces as that of full ropes. The biggest difference is they wear out much quicker (safety and elasticity after repeated falls). A full rope is usually rated for 12+ 'UIAA falls' (a particular yardstick - google it) whereas a half rope can usually only take 4 - 6.

- They are for redundancy in the case of severe rock-fall. Not a big item in the Western Cape, but in the alps pakistan etc it's a big issue. When this is the only reason, alpine climbers use 'twin' ropes, which are even thinner and are designed to have similar impact forces as a single or half when used together in parralel

- In the states, the cracks are straight up, and therefore it is simpler to climb with just a single full rope. The case for redundancy is valid though - the day before I did Half Dome, a Kiwi fell, displaced some rocks, the rockfall cut his rope and he went 7 pitches :-(

- Using half ropes combats the 'zipper effect' - when you fall, all pieces below are often yanked sideways or even perpendicularly out with severe speed and force, displacing delicate placements. With half ropes those pieces on the non-loaded rope are not affected.

- Half ropes allow 60m abseiling/retreating with less weight. The big wallers often have a haul rope of other thin rope to allow them to still abseil 60m

- On skinny moves close to the ground (15m?), or perhaps using marginal gear, having two ropes allows you to high clip one, and still have the other without slack in case either the top piece goes or you dork the clip.

Where the risk of rockfall, or extremely sharp edges is absent, and where the gear (bolts or trad) is in a perfectly straight line, then a full rope makes more sense. In all other cases - half ropes have the advantages above.

In ice-climbing impact loading on gear is important.

But if your cam/nut placement is so marginal that the impact force difference between half and single ropes is the only variable that is keeping you from decking...... well then... then you have much more pressing problems.

Does anybody know the exact difference in impact loading between half ropes and single ropes?
Laboratory conditions, naturally.


I understand everything that has been said here, and I have believed it all my whole climbing career and am most satisfied with Hector's reply:



And generally in our conditions, for multiple reasons as listed here, 2 halfs work best for trad and 1 single best for sport. (or am I being to 'sweeping-statement' about it?)

On a side note:

In clipping 1x half rope vs clipping 2x half ropes into a single beaner.

In clipping 2x half together you increase the impact loading by 20-25% on that single piece.

My personal reason for choosing between half and single on trad depends on the route.

For relatively straight lines I choose single rope with longer sling extensions. Easier rope management.

For meandering routes I choose 2 x half.

For routes I have not done = 2 x half.

So in my opinion, the main technical reason would be the route 'style'. Thats just my view on it, I may be wrong and would love to know if I am

Ant's reasons are all correct.

There is no record of 2 rope's failing in climbing. Plenty of cases of single rope failure...

I climb with Twin ropes that allow for single and separate rope use.

They have all the advantages of climbing with 2 ropes as noted above and they last long enough.

Trad ropes don't wear out as quickly as sport ropes because one does not lower off as much.

They are much more often damaged though and then it makes no difference if it is single or double ropes. I have to discard a rope at least once every 2 years from rock or other damage.