Originally Posted by
Kontact
If the bike has the original freewheel or cassette, then your crummy C20 derailleur is broken. No amount of futzing with the chain is going to make it not broken.
C20 derailleur? Say no more.
I NEVER liked those things even when they were brand new. I'd dump that turkey and replace it. If the hanger is integral with the derailleur, get a Tourney. If the hanger is part of your bike frame, get a Deore.