I use a Joker for easy big mountain routes in the uk where I'm going to be doing all the leading, (Tower Ridge with a Douglas Boulder route to start, North Wall Route on Buichaille Etive More, The Great Ridge with Direct Start on Garhb Beinn leap to mind,) where others may concider just taking a half rope. I like the security of a thicker rope and even on quite a big day don't think the weight gain actually slowed us down. If I'm in a position to do some Swiss big easy slabs in the Summer I'll use this set up. It must be said that I use this rope primarily to save faffing with two ropes on change overs rather than any scientificy / fall factory / clever reason!
However if I was going to the Alps to do some big routes as a three I'd probably take, (because I've already got them,) two 9mm - a bit more reasurring than really skinny ropes.
My experience is that using a single skinny rope is great right up to the point when it really matters - when you're looking at a fall onto a rope over an edge etc. My advice, for what it's worth, would be to forget about all the supper light Alpine stuff we read about - imagine yourself in that sort of position and then ask what the thinnest rope you would be relatively happy on would be. Then take that rope.
You need to know that I write this as a Dad to two young lads so my opinion on what to use in these situations has changed a little from where it was when I was in your position, however really ask yourself if saving on rope weight, (as long as you are still careful with other weight saving areas,) is really going to make a huge difference to speed.
In reply to TRip:
do you anticipate the seconds falling off a lot or a little? I personally would be happy with 8.5mm (the genesis are very hard wearing and suitable for this purpose) but only use smaller if I was not expecting (many) falls. I think using skinny single ropes for each second is overkill.
I’m not really sure about how much safer a 8.9mm single rope is over a 8.6mm half rope such as the Beal Cobra.
However, if I buying a new set of ropes for alpine use I would seriously consider the new Beal Unicore construction – which now come in both half rope and single rope models.
They seem ideally suited to Alpine use to me i.e. significantly harder wearing, more abrasion resistant, more “chop” resistant and can be used when sheath is damaged, all with no additional weight penalty.
In reply to 7bforever:
"significantly harder wearing, more abrasion resistant, more “chop” resistant"
Can you provide links for your claims? As far I can see all it does is stop the core and sheath seperating in the rare case that the sheath gets severely damaged. I can see this being useful in this rare case for ascending or abseiling, but in my experience mammut ropes are much more hard wearing, and abrasion resistent than beal.
In reply to TRip: FWIW I did the American Direct as a three using 8.1mm Icelines and didn't have any great concerns. However, it is a very direct and well travelled line.
With BRAND NEW ropes I'd be probably be happy with any half rope, even 7.8mm ones. Worn ropes are a different issue... However, I'd probably want more info on the style of route before making any firm decision.
If you want to use the ropes for similar routes climbing as a three subsequently then you should probably go for thicker 8.9/9.1mm singles. If you are happy after the trip to revert to using the ropes as half ropes then that points in favour of going as thin as possible.
Imho I believe 2 x skinny singles offer no real increase in safety over half ropes. If they did folks would b using them. There has been controversy over ropes passing the sharp edge test and it is highly unlikely that a 2nd fall will b over a sharp edge.
The 1st rope I bought was a mammut revelation, skinny single, as a wanted to simplify my rope work. It ok but the sheath is not great. Now I use half ropes 99% of the time, incl alps.
If I was u I would buy 2 mammut genesis, there great hard wearing lite half ropes - all my climbing mates have them, I have a mammut phoenix lighter but needs more respect