I went to college in Ithaca, NY and there was a guy in town who'd always ride around with a small dog (probably about 15 pounds) perched in a handlebar basket! It was pretty cool, the dog seemed to have perfect balance. But even if it doesn't, I am sure that you can secure a milk crate to a rear rack well enough to hold a small dog comfortably. Maybe put a pad in there so it can curl up comfortably.