When you have something of value that's rusted and you've exhausted all other rust-removal options, try naval jelly. It works well on bikes, iron and even automobiles.
Scrape the rusted surface with a wire brush to remove any loose rust.
Put on your rubber gloves and apply the naval jelly to the rusted surface with an applicator.
Allow the naval jelly to penetrate the rust for five to 10 minutes but no longer than 15 minutes.
Rinse off the naval jelly with fresh water and dry the item with a towel.
Paint the newly rust-free item with an oil-based paint within 24 hours.
If you are removing rust from a painted surface, be aware that naval jelly will remove the paint as well.
Don't use naval jelly on stainless steel. If the jelly is left on for more than 15 minutes, the surface of the product could be damaged.