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.
I use the Sheldon Brown's/Park Tool's sizing technique of big-big+1" even when replacing a chain on the same bike with the same gearing.
Yeah, but the stretch really doesn't matter. When you lay the chains on the bench, you can move the chain to keep the links aligned.