I usually transport things to make lunch with from home to work on monday, along with a week's worth of clothes, and that way I'm not using anything beyond what the grocery store used as containers. Lunch meat, bread, fruit, chips, bottles of water. But I have a small fridge in my office, so that works for me. I have panniers on my bike right now, and usually stuff my son's backpack in one side w/ his summer camp gear and my backpack in the other side, but on Monday I bungee a huge duffel bag to the top of all that
