I have the standard two water bottles on my frame (down tube and seat tube), but I've found that it's just not enough water for long rides, and I often don't have access to a source to refill them. Where else can I put water bottles? I've seen bikes with bottles attached to the back of the seat somehow, but I don't know how, and I already have a bag back there anyway for my spare tubes.
I thought about trying to fit a cage on the top tube, but it seems like it would interfere with the brake cable. And there aren't any holes there for a cage anyway, so I'd have to find one that attaches with some kind of bracket, if they even make those things anymore. Then there's the very real risk that it would just leak out when set on its side like that.