Originally Posted by
seafood
BTW, one thing I've found to work well for water insulation is bringing a plastic bag with me and putting the computer in it if I know or suspect there'll be rain.
That's what I do too. I always have a couple of garbage bags in the backpack. One goes over the laptop if it rains, another might come in handy for anything else. I have a 17 inch Lenovo that weighs over 10 pounds without all the extras.
I put up a page with more backpack details at
a bike and a backpack.
I really like backpacks and have never used panniers.