Here's how bicycle food delivery is done in Buenos Aires. Check out the pic half way down this page. Efficient, nothing to balance, and protected from the elements. This guys zipped all over town, and all night long (restaurants are open real late). Even on bad days they rush through fine restaurants to the kitchen raincoats drenched, and head back out. And probably getted tipped great those days too.
http://www.jamesvandellen.com/ba5.htm