Originally Posted by digibud

Assuming you are not commuting 1 mile each week....odds are the chain, chainrings and cogs are all nicely worn down together. If you replaced the chain it would most likely wreak all sorts of shifting havoc. I ran into that years ago with an old mtn bike that finally stopped shifting well but replacing the chain made it worse as it then had a new chain but worn cogs, hence the "keep replacing the chain regularly" OR just let the entire drivetrain run down the rabbit hole together.