Salt will do nasty things, but there is one real big thing to watch for. In a study a while back, the Navy's air maintenance departments used simple green on a massive contract deal(since on a carrier you get them pretty dirty). The stuff cleaned well, but they found after a while that the otherwise good cleaner was causing excessive ammounts of corrosion in the aluminum and magnesium parts.
Thus in the Hangar they won't allow us to use simple green as anything but a plastics and tires cleaner.

Another trick I have had a lot of success with to combat rust is to use car wax on all the metal surfaces that can be covered(paint, cogs, cables) then it works with the lubricants but the metal is not exposed when the lube washes off. Not to mention a waxed frame looks good and cleans nice.