I'm looking for a good bike to double as a commuter and weekend rider with the family (child seat will be on the back or front.) I have a short commute (3 miles) but need to take BART (the SF bay commuter train) so I'm looking for a bike that does not have wide handlebars and is not too heavy or long. I would love a vintage road bike but worry about the stability with the baby on back. I would like to find something (new or used) for <$500. It doesn't need to be fancy, I have my nicer road bike for that already. I was thinking a touring bike may fit the bill nicely but was wondering if anyone had any suggestions.