The Frame design - especially the front - is a dirt (and salt) trap. Hard to keep clean and the moisture can do a number on the frame. Few of the component parts are lubricated, painted or plated adequately to handle constant exposure. There are some lubricants and protections you can do to prevent MOST of the negative effects but it is a lot of time and effort to keep up with it. It's tough enough to keep up with the non salt exposure.
Every once in a while I take mine out in the winter and get caught on a salted road. I have to wipe and spray a lot of the underside with corrosion X after that. Keeping the corrosion and rust off are critical if you want the thing to last. That's a DeLorean - if you want to drive it.
Harold McElraft - 3354