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Originally posted by Texasphotographer

I complained about the Speedo when I first bought the bike. Dealership took it for a ride and commented it was within tolerances. Did not like the answer, but accepted it.

Now ride with a GPS and it's about 8% to high side.

Understand there is a mod you can install to make the speedo accurate, but it throws off the odometer.

Can't win.

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Originally posted by Alan_Hepburn

I don't know if this is the right place for this - if not, feel free to remove it!

Anyway, it's been noted that pretty much all motorcycle manufacturers build their product with a substantial error programmed in to the speedometer - typically 10% high is what I've seen. In the bikes I've checked myself, the speedometer reads 10% high while the odometer is reasonably accurate. Of those manufacturers that also manufacture 4 wheeled vehicles, those vehicles do not exhibit the same inaccuracy so it appears that the bikes are purposely built with this innacuracy.

My question: since there is no technical reason for the speedometers to be so innacurate, is there a legal reason?

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Originally posted by Daddio

This is one of my biggest pet peeves. I believe my speedometer is off by about 10%. It reads around 10% to the high side. I believe a generous speedometer is actually as dangerous as one that reads too low.

I have several two lane interstate highways that have 70 MPH speed limits. As I righteously set my speed at 70 I find 90% of the traffic is ready to roll over me. If I run at 77 MPH, I find I flow with about 50% of traffic. There are areas that the fast traffic is running 80-90 MPH without having to get aggressive in lane positioning. If you mix someone that thinks they are going 70, actually going just above 60, you are asking for trouble. I believe there is more danger presented by differential of speed, not actual high speed progress. It is actually safer to run with prevailing traffic. Your speedometer may be saying you are over 90. In fact you are barely in the 80 MPH range.

For me, I want to know how fast I am actually going. I do not like having to mentally adjust what my speedometer is telling me. I do not like being the cause of fast moving traffic backing up because I am going much slower than my speedo is telling me. I also don't like to think running at 80-85 MPH is just average.

If LEO decides I am making too much progress, it should be because I am going too fast. It should not be the result of math errors I am calculating on the fly. Of course the error margin is not as drastic when you travel in the lower speed ranges. I have never really had a problem reading 30 MPH while actually travelling 27.

Edit - Have you ever been asked by LEO, "Do you know how fast you were going?". On my bike I really and honestly could answer,"NO"!

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