I've got an old Bianchi I've been keeping in the garage for a while and the chain is completely rusted. I tried elbow grease and a brush, but it's not coming off much. Is there a method that actually works or do I really have to replace it?
If the brush isn't enough, try soaking the chain in white vinegar for a few hours (or even overnight), then scrub it with a wire brush or steel wool - the rust should come off much more easily. If it's really crusted on, you can also use some WD-40 or a bike-specific degreaser before scrubbing. But if the chain is really old and rusted deep down, it might be compromised even where you can't see it, so think about whether it's still worth saving or if you'd be better off just replacing it outright, especially if the Bianchi is still in use.
Vinegar works well, but watch out: once you remove the rust, if you don't dry the chain right away and thoroughly and don't lubricate it with proper oil, it'll start oxidizing again quickly. Even better is to use a specific product like WD-40 or similar, which penetrates better into hard-to-reach spots and leaves protection behind - spray it, wait about fifteen minutes, scrub with a clean cloth and then lubricate again. If the rust is really deep after you've tried these things, at that point the chain is worn out and replacing it is cheaper than dealing with it.
Deep rust doesn't come off that easily, especially if the chain's been sitting for a while. The vinegar people suggested is a good starting point, but here's the step that's missing: after you soak it, a quick scrub isn't enough. You really have to work at it, maybe with steel wool or a wire brush attached to a drill if you've got one. While you're scrubbing, the rust comes off way faster because the friction and heat help. If you don't have drill experience, that's fine doing it by hand too, it just takes patience.
Here's where it gets crucial: as soon as you're done, dry everything right away with a cloth and then - and this is important - soak the chain in a container of motor oil or chain-specific oil for at least an hour. It's not just about lubrication - the oil creates a barrier that blocks oxidation. Take the chain out, wipe off the excess with a clean cloth, and you're done. After a week or two of normal riding you'll already see it looking better.
One question though: is it just the chain that's rusted or other parts too? If your Bianchi's been sitting for a while, maybe it's worth checking the whole thing over before you ride it again.
Try putting it in a plastic bag with some crumpled aluminum foil and a bit of vinegar, seal it up tight, and shake it all for a few minutes - the chemical reaction between the aluminum and the acid removes the rust without you having to scrub like crazy. After that, rinse it, dry it completely, and apply chain oil right away, otherwise it'll go back to how it was before.
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