(Skipping the narco-violence issues plaguing the border areas) I've never been thru Tecate, but I couldn't imagine going through Tijuana on a bicycle - its a nightmare in a car! South of the Ensenada area there are almost no services (and a lack of water sources). Crazyguyonabike might have some better info, but the one time I drove down to LaPaz would not be something I'd attempt on a bicycle.