Speedo accuracy. If your '99 650 is showing 37mph on the speedo.

...how fast are you really going?

I have a 70 profile front tyre if that makes much difference?


I ask as i was (shamefully) flashed by a speed camera on friday whilst the speedo was showing that speed (30mph zone obviously).


This was in Lincoln. I know some areas have a scheme whereby if you were a little over the speed camera 'threshold', 35-37mph if i remember correctly, then you have the option of attending a 'rehab' course instead.

I would expect if my speedo was showing 37, i would have actually been going more like 34-35, so it is surprising that the camera went off.


Thanks

Originally Posted by lloyd_christmas

I know some areas have a scheme whereby if you were a little over the speed camera 'threshold', 35-37mph if i remember correctly, then you have the option of attending a 'rehab' course instead.

Very rare for this to be offered in a 20 or 30 limit. Why do you have a 70 profile tyre on?

Originally Posted by Dangerous Dave

Very rare for this to be offered in a 20 or 30 limit. Why do you have a 70 profile tyre on?

The only mentions i have heard of the schemes, have been in reference to 30mph limits.

I am skint at the moment so i buy second hand tyres from ebay and fit them myself. My bike failed it's MOT due to the front tyre (60 profile), so i needed a 'new' one. A 70 profile was what was being sold on ebay at the time, so bought it.

I have dropped the yokes a few mm to compensate and the bike is handling as well, if not better, that ever.

I seem to remember reading on here, that a 70 profile tyre cancels out a lot of the speedo error, which makes sense i suppose.

how much error is there in the speedo then?

and the rule is 10% + 1/2 cant remember which, so a camera could well go off at 34/35. My mate got a ticket come through when he first passed, was doing 34/35 or something and got the 3 points

Originally Posted by lloyd_christmas

The only mentions i have heard of the schemes, have been in reference to 30mph limits.

Yes but not in conjunction with a fixed speed camera as these are set slightly above the tolerences which means you were doing more than the 10% + 1mph.

Originally Posted by Draper

how much error is there in the speedo then?

and the rule is 10% + 1/2 cant remember which, so a camera could well go off at 34/35. My mate got a ticket come through when he first passed, was doing 34/35 or something and got the 3 points

Yes, i think it is +10%, +2mph, although there is no legal obligation for cameras to go off at that, i believe they can be set to 31mph, but nobody has them set that low yet.

Originally Posted by Dangerous Dave

Yes but not in conjunction with a fixed speed camera as these are set slightly above the tolerences which means you were doing more than the 10% + 1mph.

I see.


In that case my speedo must be more or less spot on then, at that speed.

Just in case anybody cares, i didn't get a ticket

is the SV speed not taken from the front sprocket like most modern bikes?

Neio, the SV speedo sensor is on the front wheel