Bicycle clothing is light and made to stop wind. What I like about bike shirts is that many are more windproof on the front and not the back - this works out well for carrying a backpack without sweating too much on the back.

I friend of mine who does alpine climbing puts a 2-3 oz windshirt UNDER her outer layer- stops the wind but is not exposed to wear and tear - rock climbers get a lot of that.

I personally like Arcterex. They make alpine climbing specific stuff. Not the lightest but wears forever. I choke on the $$$!! every time I buy an Arcterex item, but soon it is my favorite.