In Seattle downtown there is Bikestation to safely leave your bicycle. I park on the UW campus under a covered ourdoor lockup area, which is not secure. I leave my helmet on the handlbars and my lights attached. I don't worry too much since I like a vintage ride, it doesn't seem to be a crime magnet. I tend to take more stuff off my bike (like lights and whatnot) if I lock up on University Way or other really urban situations. But in any case, I think it is usually pretty safe to lock up to public seattle street rack so long as you are using a quality U lock and don't have a lot of components that are desirable. Covered is ideal. But there is always a bag over the seat-- which I do for my Brooks when I park elsewhere.