Amid the spectrum of stuff lurking in the garage are a Bonty carbon crank and stem. The metal bits of both are chrome(?) plated and said plating has started coming away. I presume it’s lifting as the metal beneath corrodes so how do I remove the finish without resorting to some form of acid bath?

most of the methods I’m aware of short of physically sanding / grinding it off are things you wouldn’t want to try at home – either the materials you need aren’t much fun or the byproducts ( like Hexavalent Chromium) are really nasty.

I’d be looking for a local metal plating / finishing company who can probably strip and then re-chrome them for you.

Edit – I’d be surprised if anything on a carbon component would be steel through and there’d be no reason to chrome-plate aluminium.

Actually if you do a google of Bontrager, chrome and flaking you’ll see lots of chat about a chrome like finish flaking off components (and Trek having to replace a lot of stuff under warrantee) – its not chrome because the components aren’t steel, and its not anodising as that doesn’t flake so its probably some sort of metallic paint or powder coat type finish. I’d try soaking the bits in various solvents or strippers (one solvent at a time- lets not mix them together!) and see if that removes it

So it is. I’ve sent a request to Trek on the off chance they have spares. Failing that we shall investigate chemical options.