Speedometer error?

Steven Bixby steven at bixbys.net
Tue Sep 1 19:14:23 PDT 2009

Virtually all Japanese bikes (and I think most German bikes?) are set 
conservatively.  At one time in the past, I understood the reason for 
this being a combination of:

1:  Mechanics (and electronics?) vary, unless they cost more than the 
bike does.
2:  The US has penalties on the too-aggressive side of estimation but 
not the conservative side.
3:  Tires wear - new tires show more-conservative speeds than 
almost-shot tires, and I'm sure if people are changing tire sizes here 
and there, it also fits into the variation part.

All five bikes in my driveway vary from about 5 to 8% optimistically, as 
determined by a GPS unit in straight & (low-)level flight.

Alan Nicholls wrote:
> Well, I've noticed lately, when I'm cruising on the freeway at 70, people
> are blowing past me, and when I'm doing 85, I'm slowing passing people.  Is
> the GPZ's speedometer off?  I know the Ninja 250 has an 8% error, but does
> the GPZ suffer from the same?

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