I have only used EvopoRust on small parts. I am impressed with how well it works and the finish that it leaves behind. Much better than Oxalic Acid. OA will remove the rust. The problem is that it eats up some steel and leaves more pit marks, in my opinion, than Evaporust. I would start with Evaporust. Try it on small parts first. Then try the frame.

The 6 months ago, I cleaned up a rusty cassette. I ended up painting it to get a nicer finish. This time I used Evoporust and figured that the chemical rust removal would just save the work. When I cleaned the parts off I was impressed to see that I would not even have to paint them. I will need to get some oil onto the steel, because the rust will come back if I don't do something.