Yes, vinegar. For years, I busted my ass using wire wheels on the drill, steel-wool, cleaners, etcetera. Well, no more of that! Simple white vinegar and a plastic tub is enough to solve our rusty woes. Check it out.
Step 1: get the cheapest gallon of white vinegar you can find at the store. It does not need to be good stuff, because all we need are its weak acidic properties, anyhow.
Step 2: purchase a tub big enough for the item you’d like to remove the rust from. Many folks use those ‘under the bed’ boxes, and that way they can dip entire bike frames. However, much smaller tubs can be used for things like cranks, bolts, stems, sprockets, tools, and the like.
Step 3: completely submerse the rusty item into the vinegar. If you only have bolts and small stuff to clean, a good idea is to tilt the tub up. That way, you can use less vinegar and soak the items in the corner/crease of it. If your tub came with a lid, I recommend using it, because this stuff evaporates eventually.
Step 4: leave the item in for a couple of hours. At that time, take it out and wipe it off with a rag. Then, take a small, copper-type wire brush very lightly on the surface of the item. The rust will just fall off. You could also use steel wool or anything else that won’t scratch the surface of the item. If all the rust comes off, you are good to go. If some is being stubborn, you can dip the item again for a few more hours.
This process is way more simple than all the effort it takes to remove the rust manually, and it’s easier on the chrome items, too. The lids are heavily recommended, though, because this stuff kinda reeks. The garage smells like Easter-egg dye if you don’t employ a lid. I have used this process on rusty tools, cranks, sprockets, necks, bolts, washers – really, anything that looks like it could use a good surface cleaning. The beauty of the white vinegar is that it’s acidic enough to eat away at the rust, but if you don’t leave the item in there for a week, it won’t eat it, as well. Vinegar is very gentle.
I always coat the item in a very light sheen of oil or WD40 after it dries, and I’m satisfied with its condition, to prevent flash-rusting. This process really works; it can turn a totally wasted BMX part into a shiny, new-looking part.
***EDITED TO ADD: I dropped a bike chain in there the other day, and left in a full day. The chain is now in a million pieces. Soak chains in oil, not vinegar. :P