I am putting a 19 on my TBA today. I cant seem to figure the science of it but figure I should not be looking for 6th gear at 60 and the bike should have enough low end torgue to handle the larger sprocket. I would assume jumping up two teeth will be about a 10% change in lower RPMs at high end and a 10% disadvantage at low end. As I have no real urge to be a drag racer with 60ish hp I doubt the lower performance at low end will be a big deal to me.

I try to aggravate one person a day. Today may be your day.