Originally Posted by
gregstandt
I read about protecting your frame from rust. However my bars a CrMo and they don't rust so why would my frame which is also made from CrMo steel rust? Are there different types of CrMo? Or are different parts of the frame made from other materials that can rust? Huh?
Your bars were either painted, plated or coated with one of the newer bake-on coatings.
Unprotected Cr-Mo (and yes, there are several grades) most definitely rusts. The Cr and Mo content are there to provide strength and the levels are much too low to provide rust protection. As noted above, strainless steels have a minimum of 11.5% Cr and most have 13 to 18% Cr.