Originally Posted by
HillRider
This can result in making the new chain too long if the old one is badly worn. Assuming 110 "pitches" in a typical chain, the worn chain could be 1/2" longer than new if worn to the 1% mark and 1" longer than new if really bad at 2% wear.
It's pretty hard to make a chain that's 1/2" longer. If the old chain had elongated by a full inch you're likely to have more problems than just a too-long chain.