Originally Posted by
Bearonabike
I'm thinking too narrow a chain. Given the post above about the tolerance I am looking for, the chain is correctly sized for a 5 speed friction freewheel.
In all likelihood you won't find a chain marketed as a 5s, but you might find one marked 6s which will be the same width. Otherwise any chain marked 7s or 8s will only be slightly narrower and should run fine. I use a 8s chain on my 6s freewheel (same spacing as 5s) with absolutely no problems.