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Discussion Starter #1 (Edited)
Hello

I have just installed, on my Desert Sled, a Trailtech Vector tripmaster that I've been using when I used to ride in road rallies.

This is the Striker model (the Vector isn't sold anymore) : compteur Striker pour motos d'enduro - Boutique Trailtech

After measuring the front wheel circumference, then comparing the obtained result on 5 km straight road with kilometer indication and setting a more accurate wheel circumference, I can reach an accuracy of 10 meters on 1000 meters.

This allows me to tell you that our Scrambler odometer and speedometer is erroneous by excess (as required by law in many countries)

When reading 90 km/h on the Scrambler speedometer, the real speed is 83 km/h.
When reading 54.7 km on the Scrambler odometer, the real distance is 53.5 km.

If some of you think that this Vector tripmaster is erroneous, I would just tell them I've succeeded to approach from 1 or 2 seconds the required average speed on a regularity stage during the Moto Tour in France. So, when correctly calibrated, it is really an accurate device.
 

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Your odo number is very similar to what I have unscientifically observed vs GPS. About 6.25% low.
Haven't tried to check the trip.

I have used devices similar to the Striker: very accurate.
 

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This was to be expected right. I had many bikes and nearly all speedos would lie. The worst was my BMW G650X Challenge (luckily the speedo was programmable for wheel diameter, so easily fixed).
 

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Although it's just guessing but I've suspected that my speedometer reads faster than I'm actually going. I have a 65 mile commute and in my truck I'm usually around 80 - 85 mph most of the time but on my bike it's more like 85 - 92. I'm curious what others have found. I'm just guessing.
 

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This was to be expected right. I had many bikes and nearly all speedos would lie. The worst was my BMW G650X Challenge (luckily the speedo was programmable for wheel diameter, so easily fixed).
My 1290sdr is the worst I've ever seen, it's way over the legal 10% discrepancy and the only fix is to change the ABS ring. KTM themselves were not interested and a guy in Australia designed and made them. Not what you'd expect from a quality bike.
As far as the Scrambler is concerned I find the speedo pretty much spot on at the legal speeds, according to the smiley/pissed off faces in the speed controls.
 

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The Scrambler handbook states that the speedometer is intended to read 5% fast :
"The instrument panel receives information about the actual motorcycle speed (calculated in km/h) and displays the value increased by 5% and converted in the set unit of measurement (km/h or mph)."
It is actually much better than many other bikes that I've owned. My 907 reads 60 at an actual 70 and reads 120 at an actual 100mph. The carbed 900SS I used to have was so bad that I ran a bicycle speedo on it so I knew what speed I was really doing.
 

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The Scrambler handbook states that the speedometer is intended to read 5% fast :
"The instrument panel receives information about the actual motorcycle speed (calculated in km/h) and displays the value increased by 5% and converted in the set unit of measurement (km/h or mph)."
It is actually much better than many other bikes that I've owned. My 907 reads 60 at an actual 70 and reads 120 at an actual 100mph. The carbed 900SS I used to have was so bad that I ran a bicycle speedo on it so I knew what speed I was really doing.
Aye Derek, the further up the adrenalin scale we go the less accurate they get. Manufacturers tend try to err on the side of caution and show over as showing under is against construction and use regs.
I find even with the KTM as far out as it is I still just find the sweet spot and keep 'mostly' under the jail threshold.
 

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For the UK speedometers are allowed to read up to 10% fast but 0% slow. I suspect it's much the same in the rest of Europe and is why manufactures aim for the middle ground of 5% fast.
 
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Funny timing of this thread as the police set up one of those radar set ups that flash your speed to you. I went through doing 59 and it read 54 so I guess it a bit of confirmation that the speedos are off.
 

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For an accurate indication of your speed fit a satnav which should show your true speed (It might have a margin of error but I'm sure it will be very small)
 
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Discussion Starter #13
For an accurate indication of your speed fit a satnav which should show your true speed (It might have a margin of error but I'm sure it will be very small)
On a straight road, yes. On a curved road, it will be less accurate. GPS signal is sent to the Satnav device every second. In one second, in a curve, you will do more distance than the straight line between the 2 measurement points. If you cumulate this on a very curvy road, the error will be quite large.
 
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