European regulations require speedometer testing at 40, 80 and 120 kph. Accuracy requirements for motorcycles are a) the speedometer must never read less than the actual speed and b) the maximum amount the speedometer can read above the actual speed is 10% of the test speed plus 8 kph. So at a test speed of 80 kph the speedometer could read as much as 92 kph and still comply with the regulation.

Your math is different than mine.

A test speed of (80 kph + 10-percent = 88 kph) + (8 kph) = 96 kph. But you knew that.

What I find more interesting is that a test speed of 80 kph and an indicated speed of 96 kph yields an error of 20.0-percent, which is huge.

Tim