Rusty Freewheel/Chain - Challenged To Remove The Rust With Evaporust - YouTube
Had a slightly rusty chain and cassette. Used wd40 and a cloth to clean up most of it. Should I worry about this leftover? Was trying to avoid tearing up the bike... :
Rusty chain and back cassette – Replace or repair? - Bicycles Stack Exchange
How to Remove Rust from a Mountain Bike Chain [with Video] | DIY Mountain Bike