This tool is still in beta version. Shoud you find a bug on wish to give some feedback, you can do so on Old-Droppers. To use the tool, chose a gearbox in the dropdown menus. You can also try your own ratios by using the fields below the dropdown menus (up to 5 speed). The diff value goes into the "P" Field.

Rear Tyres : Gearboxes : Width Height Wheel Coefficient to be applied : de 0.00 à 1.00 Max RPM : T/min Circumference = 202.63 cm Max RPM = 6000 T/min #1 : Pick a gearbox