[Maiaibing]

Am restoring an old bike (apx 20 y.o.). Most parts are done now, but I'm uncertain what to do with the rusty front chainring.

Its not horrible, but it has a "coat" of rust which needs to go. I could machine polish it off, but I worry that if do that it'll start rusting again before the bike even hits the road.

It would be nice to keep the original crankset which looks beautiful and runs surprisingly well (chainring itself is not the replaceable type).

Is there something I can treat it with after a machine polish - or is there a milder treatment that will do the trick?

 

[JCavilia]

I'd try a chemical rust remover, followed by a polish with a rust inhibitor. Lots to choose from at the hardware store.

What makes you think it will start rusting again so fast?

 

[Maiaibing]

Will try Phosphoric acid

I'd try a chemical rust remover, followed by a polish with a rust inhibitor. Lots to choose from at the hardware store.

Good idea. I did not think of using chemistry. But will try Phosphoric Acid which should work well with iron.

Any suggestions for a specific rust inhibitor? The ones I know of are in fact only oils, which wash away quickly.

 

[forge55b]

why not have it anodized or powder coated?

 

[JCavilia]

Good idea. I did not think of using chemistry. But will try Phosphoric Acid which should work well with iron.

Any suggestions for a specific rust inhibitor? The ones I know of are in fact only oils, which wash away quickly.

Many commercial metal polishes (e.g., Mother's) contain corrosion inhibitors. I'd go to an auto parts or hardware store and read the labels.

It's not going to rust again that fast if you don't leave it out in the rain.

 

[DrSmile]

I use Evapo-rust. I like it because it's a chelating agent not an acid. Powder-coating it afterwards sounds like a great idea!

 

[deltarocketscientist]

Am restoring an old bike (apx 20 y.o.). Most parts are done now, but I'm uncertain what to do with the rusty front chainring.

Its not horrible, but it has a "coat" of rust which needs to go. I could machine polish it off, but I worry that if do that it'll start rusting again before the bike even hits the road.

It would be nice to keep the original crankset which looks beautiful and runs surprisingly well (chainring itself is not the replaceable type).

Is there something I can treat it with after a machine polish - or is there a milder treatment that will do the trick?

So anodizing only works with Aluminum so that is not a solution. Powder coating would be a good solution except it will add thickness to the teeth on the chain ring and will likely chip off quickly, unless it's just for display.
you co
uld do what golfers do and by a chemical coating, but that would turn the metal black and again likely won't last. Take it to a chrome shop and see what they can do, might get surprised.
My 2cents

 

[JCavilia]

I'm guessing a little here, but I don't think this is a high-end bike. (steel ring swaged to the crank).

OP likes it, and it's worth some effort to restore, but not worth a lot of money, so powder-coating, chrome plating, etc., may not make a lot of sense. But commercial rust removers like Naval Jelly, followed by a metal polish, will do the trick cheaply.

That's what I'd do.

 

[tlg]

Powder coating would be a good solution except it will add thickness to the teeth on the chain ring and will likely chip off quickly, unless it's just for display.

There's a simple solution to that. Mask the teeth before painting. They won't rust because they'll (hopefully) be covered in lube from the chain.

If it were me, after removing the rust, if the bare metal was in good condition and looked nice, I'd just get a can of automotive clear coat and spray it. If it didn't clean up well, then I'd probably spray paint it black.
I think powder coat is overkill.