Well, I ordered the Z33 chain from amazon
https://www.amazon.com/KMC-Chain-Spe...ords=z33+chain
but when I got the package, it says "18 speed" and "touring - indexed shifting" on the outside. Is this just a sales pitch? On the back, it says compatible with "6-12-18-21 speed." The stated width is 7.3mm.
The non-nickel plated version
https://www.amazon.com/KMC-Bicycle-5...ords=z33+chain
has a stated width of 7.8mm. I was hoping that the width on the nickel plated version would be the same.
In any case, am I good to go or should I return it? It's possible I'll replace the rear freewheel with a 6 speed, maybe a Shimano.
Incidentally, I measured the old chain and it appears to have zero stretch if I'm doing this right . I lined up a 12 in ruler with the pins and everything lines up just right. However, as I indicated before, it appears to be 2 links short if I go with the big-big measurement (big cog in rear to big sprocket in front, add 2 links to the shortest possible linkage).