Just so you know the Pooh-Bah has to do with how many post he has make and nothing to do with his name sort of like the stranger is below your handle. No you don't have to get a different chain for either the 18 or 19 tooth sprockets. I also run the 18 as far as RPM just depends how fast your going , but like he said I don't tend to look for 6th out on the highway.
