Well lets see, Sheldon Brown rides almost every day on a steel bike that was manufactured in 1918...that is not a misprint! He is not the least bit concerned about rusting and he lives in Boston; nor is he concerned the frame is turning into a noodle. How many miles does this old bike have? He's never said but he has hinted that it has more than any bike he's ever seen. Bikes back in those days had no technology for rust prevention, the frames were just straight gauge gas pipe.

Todays mid to highend steel bikes are either zinc (as cars are) or chrome coated to prevent rust. I had a 79 Schwinn Traveler with Tange cro-mo frame that I bought new when I lived on the coast to be my beater bike instead of my good one. I rode that bike in the rain, along the beach, on the sand of the beach, in the ocean water and ocean spray, parked outside the apartment where it was rained on and fogged on; and it only had light surface rust where the paint had been scratched and just a little inside the bottom bracket when I threw the frame away last January and it was not treated with zinc, chromed or Framesaver. My current bike is a 84 Reynolds 531 steel, and this on I have rode a lot and has just over 140,000 miles and a large percentage of that is mountain road riding, but rarely ridden in rain, and it has no rust anywhere. My LBS mechanic test rode the bike about 2 years ago because I thought the frame was getting "noodley" and time to buy a new one . After he took it for a 8 mile ride and told me to save my money because the frame felt very responsive to him.

So A.) don't worry about a steel or TI frame getting weak on you, it will outlast you; and B.) Don't worry to much about the rust factor, but if it will make you sleep better at night then treat it with Framesaver.