Are you climbing a low to moderately angled glacier? You need a rope for crevasse rescue only, but not for catching any real leader falls, and you don’t want to carry any more weight or length than you have to.
Consider a static rope. If your only purpose of the rope is for crevasse rescue, then you don’t need the dynamic qualities of a typical lead climbing rope. In fact, the extra stretch in a dynamic rope (especially the skinny ones) will result in a longer fall and will add unwanted stretch to any raising system you may need to build.
Also, many static ropes have a rougher, more durable sheath, which can help prusiks and friction knots hold better.
(Note: the Petzl RAD system, an advanced set-up designed specifically for crevasse rescue, uses very low stretch static rope.)
Here's a quote on the subject from “The Mountain Guide Manual” by Marc Chauvin and Rob Coppolillo (pg 243):
“Because of all the dynamic aspects to a crevasse fall - climbers sliding on the snow surface and the rope and bending over and cutting into the lip - it is becoming acceptable to use static rope.
In fact, Petzl has conducted tests that suggested the spring/rebound nature of a dynamic rope actually makes it more difficult to stop a fall.”
Here’s a bit of Youtube chat about the topic with another pro guide:
Keep in mind that so-called static rope is more accurately called semi-static. It actually has about 1/3 the stretch of a dynamic rope, so don't get the idea you’re tied into a steel cable. A lot of climbers seem to F R E A K O U T when you suggest they actually do real climbing on a static rope, but the histrionics are not necessary.
In reality, semi-static rope should be a okay for falls having a fall factor of about one or less, which should be pretty much everything in alpine mountaineering. So, while we are talking here about using it primarily for glacier travel, if you ever have to do a modest lead climb on it, you should still be fine.
You can get the rope from a bulk cordage spool in your local climb shop. This will probably be a lot less expensive than a new dynamic climbing rope.
Or, you can buy static cord pre-packaged from Black Diamond (see image) and a few other vendors. 8mm would be a good choice.
If you tromple on your rope with crampons and maybe put a spike through it (something darn easy to do on a glacier climb) you haven’t wrecked an expensive lead rope.
Be sure to use triple wrap prusiks made from skinny 5 mm cord to be sure your friction knots hold on the narrow diameter line.
You might want to add a wash-in dry treatment for your rope such as Nikwax RopeProof.
The weight savings is amazing! My 10.0mm, 60 meter rock rope weighs 8 lbs. 10oz (3,912 grams), or 65 grams per meter (pretty standard for a burly rock rope).
My skinny 8mm, 40 meter glacier rope? How about a featherweight 3 lbs. 4oz (1,474 grams), a mere 37 grams per meter and packs down to about volleyball size.
This tip is from "The Mountain Guide Manual" by Marc Chauvin and Rob Coppolillo, and "The Mountaineering Handbook" by Craig Connally.