Pete, until you get an mph speedo there is an easy way to calculate speed. First, the ratio is 0.62mph/kph, which of course means 100 kph is 62 mph. Also, when in 4th gear you can take the tachometer reading and double it to get a very close approximation of your speed, so when the tach is reading 30 (3000 rpm) you're traveling 60 mph, 35 = 70 mph, 25 = 50 mph, and so on.