EvenmoreXS
1981 XS650
I had occasionj to revisit my RPM vs MPH Excel spreadsheet and corrected the nominal rolling distance for the 16" rear wheel. It is essentially the same as the 18" (1" difference)
Click here for the spreadsheet > RPM vs MPH
RPM at 60 MPH for the 18" wheel is 4117 vs 4170 for the 16" with stock 17/34 sprockets.
When calculating RPM vs MPH, you have to use rolling distance as there is no way to calculate or measure the effective diameter or the effective circumference of a motorcycle tire. Rolling distance is the distance that the motorcycle moves forward for one revolution of the rear wheel.
You are a fountain of knowledge Pete