Do NOT buy one of these folding bikes (like this Dahon Curve). You'll find they are lightweight, strong, carry a lot of weight, go pretty much as fast as a full-sized bike, are more responsive, and fold-up in a few seconds to fit behind your pickup truck seat for use in an emergency, or even just for fun.

My Curve comes with a fitting above the front wheel in this foto that you can use to attach (in about one second) many load carrying accessories from Klickfix. I normally attach their wire basket, but had it off in this pic.

Oh, and the seat post is heavier than necessary because it contains a built-in bicycle pump. Sorry for the convenience.