I do a lot of shopping with my bike. It would be great of the rear carrier was first of all big enough for a whole FULL bag of groceries and second, expandable for when you buy two bags of groceries and maybe even just a little more in case you over-do it.

On one of my bikes, I have a big old wire milk crate with stretchie webbing over the top. That works really well. It would be nice to have something like that, but that looked cool. The milk crate look is just not cool at all.