What breed?
I think you should have a dog. They are great companions. Your be a good dog owner and I sense you need something to care for and love. We all do. Some living thing. Ive grown fond of my garter snakes that used to scare. me to death.
Im going to start with guinea hens and a barn cat. If I take to farm life im going to need a dog.
I guess it also depends on your leash laws, since you bike in the city.