I went up one tooth on my America to an 18 tooth. For solo riding it was great but for 2-up riding, that I do most of the time, it was a pain in the butt. I found myself down shifting a LOT more then before for those up hill climbs or coming out of a curve that I had to down shift to. I would rather have the stock 17 tooth any day. Yea, you no longer reach for that 6th gear with the 18 tooth but you down shift a lot more then the reaching for 6th. Just my opinion.
Ride Safe
