Originally Posted by
msbiker
the replacement chain was sized by matching the new chain to the old chain, matching link for link.
But we don't know what method, if any, was used to size the chain.
Put the chain on the biggest ring & cog.
Take 2 skinny screw drivers or similar.
On a long run of chain, insert them a few links apart.
Keeping them parallel, move them closer to each other and see how much chain slack you have.
If you have an inch, you're "safe".
You would theoretically only need 1/2" additional, but you don't want the chain "taut" or close to.
Give it a bit of slack for cogs/rings that may have a bit "eccentricity" in their rotation.