speedo calibration

[Hughdemann]

Is there someplace that I can get my speedometer calibrated? I was on the Pa. turnpike yesterday, and their radar speed sign said 68, but my speedo indicated 78. The majority of the traffic was running at my indicated 75 to 80, which I didn't believe. The ten mph lower speed seemed more reasonable. However, now I'm worried about readings at lower speeds. Can dealers re-calibrate?

Thanks
Hugh
:???:

[Nic900]

Hi,
First thing I would do I'd check to see if your speedo really is out, I would suspect a radar gun from being out before my speedo. I have always done it like this. Get a friend to drive/ride in-front of you and when you reach a predetermined speed, say 20mph he puts his hazards on for ten seconds or so, then the same at 30, 50, 70mph. If you needle hits the mark -/+ 2mph then you're OK. If you want to be double sure do the same thing using different vehicles.
Apart from that, a snagging cable can cause wrong readings on speedos, or the wrong wheel or tyre size, but I've never come across a speedo being more than a mile or two out on a bike.

Hope this helps
Cheers
Nic
:chug: