Originally Posted by spinnaker
Wow advice all over the board (no pun intended). But thanks, I guess I will have to digest this all and decide for myself.
What are the differences between
this chain checker and
this chain checker?
If it is time to change the chain then does that mean it is time to change the cassette?
Beh... a ruler does the exact same thing as the chain checker things. What you are really interested in is how far the chain has deviated off the normal (rivets should line up exactly on 12") and then you have an acceptable stretch before you replace. 1/16"
You normally only replace a cassette if you've been lazy and let the chain really wear, which also screws up the cassette. This is characterized by the new chain slipping and otherwise being very crappy on your old cassette.
That is why it is better to replace chains than cassettes -> they cost less to.