I am heading to Mt Blanc next year and wondered what rope would be appropriate to take for the walk to the summit. My bro-in-law and me plan to use a guide to get some skills, acclimitise and bag some lower peaks, and then join some friends for a push on Mt Blanc. We'll rope together but I wondered what size rope would be suitable. We both have climbing ropes (both over 10mm dia), but I also have a pair of 8mm half ropes that I bought off a guy who'd taken a 20m leader fall on them, and that I planned only to use for tat. Could I use one of the lighter half ropes even tho it's been "pre-stretched" (:-o)? And what length would be optimum ?