Speedo Accuracy

[Dave Price]

After recently fitting a Garmin Quest Sat Nav, I did a comparison of speedo accuracy.
The speedo on the 1200GS, which is fitted with O2Os, was consistently within 1mph of the Quests speed display. I appreciate that the gps might have a slight inaccuracy, however, its still nice to see a fairly accurate speedometer.
Over the years I haven't seen many speedometers that were much better than 8% over the actual speed and never under.
BTW my car speedo was reading on average, 6% below, throughout the range.
I'm not sure how much the O2Os affect the overall gearing, but I suspect there would be a difference to the semi off road tyres.

 

[Wraithwrider]

Dave

The speedo is just as accurate with the normal 'semi off road' tyres.

This is partly a good thing and partly not I think.

It's not uncommon for speedos to read 10% high. When playing the game of 'I know that, and GATSO's are set at speed limit plus 10% plus 5 mph it can get the gamblers amongst us into trouble!'

 

[Mouse]

On the other hand it can be amusing when you overtake cars while going past a GATSO and you know you are doing exactly 60mph And the car driver is panic braking from 45 cos he just saw the camera

 

[Dave Price]

On the other hand it can be amusing when you overtake cars while going past a GATSO and you know you are doing exactly 60mph And the car driver is panic braking from 45 cos he just saw the camera

Yes, they then accelerate to 70mph and brake for the next corner, which they could have negotiated at 90mph and enter the next 30 limit at 50mph. You just want to drag them out of the car and shake them.

 

[Abelrider]

You just want to drag them out of the car and shake them.

Steady on old chap! Thats a bit strong!
Think of your blood pressure.

 

[Russ]

I found my tourance shod 1200 is equally accurate, when i was using my GPS.

What is shocking was how innaccurate my old VFR speedo was, once you were in the realms of a ton plus, it was 10% over reading! Which means my 154 (on the autoroute) was more likely 138, whereas i've got the GS to 132 indicated and actual!

not much in it!

My favourite drivers have to be what i call the '40 drifters' the drive at 40mph everywhere, down the NSL lanes at 40 mph, then straight through the 30mph signs at 40 and through the 30 at 40...numpties

 

[IanC]

Mine, shod with Anakee's, always reads 100mph when GPS says 98mph.

That's pretty good IMO - my Pan (with 020's) reads 6mph fast at 100mph (GPS says 94).