to lead on a single half rope?
on alpine climbs I've done this before on stuff I know I won't fall on, like 5.7. it's a 8.6 50M.
how hard is it to break a rope? this weekend I'm going in to do the serpintine arete. I don't want to carry 2 ropes for the 4-5 pitches that are 5.5 or so, becasue I don't want to carry them on the upper 4th class.

Do it all the time in the BC.

Mammut Genesis 8.6 Super Dry Coat 60m.

I lead on a half rope all the time. On harder pitches I will double it up.

sweet. I'll just bring one then, light is right!

I've done it alot too, but I wouldn't want to test a skinny rope by falling on it, especially with the type of runout, simul-climbing you often do in the backcountry.

Just don't test out the capacity over a sharp edge...

Each strand of a half rope system is rated to catch a leader fall by itself, but like others have said I'd be wary of sharp edges and the possibility of rockfall.

Still, I do this kind of thing too when the climbing is easy and I want to save weight. Folding it over for short pitches sounds like something I might try sometime ..

on loose 4th class often I'll put the rope away, if my partner is comfortable with it. the reason, it's safer. the rope can catch loose blocks and bring them down onto it self and me. the closest I've come to being hit by rockfall was being roped up on loose 4th class terrain. the rock missed me by a couple feet and then nailed the rope, almost cutting it in half. I didn't notice the core shot until halfway down a rap!