DirtJapan.com gear ratio calculator script for car/motorcycle.
- you can examin new sprocket and new tire.

You can check max-speed and relationship between any gears.
This site help you to choise sprocket and gear position in racing course.
for bicycles is here  Japanese version is here.

post bookmark to del.icio.us
Please tell me new data via email: gearratio(at)dirtjapan.com

select machine
select tire
please fine adjust after selecting machine.
if you don't find your machine, input data direct.
1st ratio 2nd ratio 1s 2s 3s 4s 5s 6s revlimit shift
drive driven tire peri accuracy graphsize mile/km

/ -

reffer URL can bookmark your machine.

This tool has made for calculating the speed(MPH,km/h) for a given transmission gear ratio.
You can select any motorcycles and cars and calculate speed.
And you can change any parameters(sprocket, tire, revlimit, etc..).

Speed calculating formulas are as follows.
speed = (RPM*60) * (tire peripheral length) / (final gear ratio)
tire peripheral length = Diameter * Pi(3.14..)
Diameter(mm) = width * (aspect ratio/100)*2 + size(inch) * 25.4