Originally Posted by
treadtread
I'm getting a bungee net. My laptop bag has 2 thick layers of padding, and I added a sleeve and will also but bubble wrap. Can just bungee the bag to the rack.
edited to add: I'm currently using a laptop bag in a messenger bag style. Backpack is too sweaty, and messenger style laptop bag is not as balanced as I like.
I used to run with a flat beverage crate mounted to the rack and just toss my backpack on it. I've posted pics of this set up before, but I'll do it again for some of the newer members.

BTW, the bag in the pic is a large
Banjo Brothers backpack that I have since traded for a rack trunk that didn't quite work out for commuting purposes- great for extended recreational riding, though.