Steel wool
I'm rebuilding a Robin Hood, of uncertain vintage but at least 30 years old.
It hasn't been abused, and it was keep in a garage or a shed out back. Over the years, though, the chrome bits (and everything on this bike is steel -- not a piece of aluminum) had picked up dots of rust, a lot of them -- handlebars, stem, wheels, cranks, anything and everything, some better, some worse, than others.
I was trying to polish it up when my wife walked by and said, "You know, me and my Dad always used steel wool."
I happened to have some 0000 steel wool (the fine stuff) in my shop, so I went at it with a fistful.
Amazing what steel wool can do!
A lot of rust just disappeared. I'm not saying the metal looks like new, but it does shine, and it is not covered with rust.
If you look closely, you can clearly see where the rust was -- little pits and bumps. But, man, what a difference!