Speedo error

[MarkC]

Hi all,
Newbie to the site, I have just bought and XR650R in SM trim (my 3rd XR so far in my life). It has a 17inch front as apposed to the 21 of the offroad rim. I was just wondering if anyone knew what kind of speedo difference that will make in a percentage term. so if I was going 50kmh, would I only be going 45kmh in actual terms if I had the 21 inch front on.
Any help would be appreciated.
Regards
Mark

[jasonbc]

Hi all,
Newbie to the site, I have just bought and XR650R in SM trim (my 3rd XR so far in my life). It has a 17inch front as apposed to the 21 of the offroad rim. I was just wondering if anyone knew what kind of speedo difference that will make in a percentage term. so if I was going 50kmh, would I only be going 45kmh in actual terms if I had the 21 inch front on.
Any help would be appreciated.
Regards
Mark

If you have a sat nav for car/bike put that on the bike and the speedo on the sat nav will show you how far out it is

[Snaphappy]

I know some of the SM lot have push-bike style speedos fitted, the little magnet sensor types not 100% accurate but cheap

[jasonbc]

I know some of the SM lot have push-bike style speedos fitted, the little magnet sensor types not 100% accurate but cheap

that all you need to get an mot. My trail tech dashboard computer uses the same thing it's accurate you calibrate it yourself it's bang on with speedo in my tomtom

[MarkC]

Thanks for the tips

Think I will try get my tom tom out and give it a go, probably duct tape it to the bike to get the accurate readings

I don't know for sure but recon it would be okay for the MOT as they don't check the current speedos accuracy, will let you know if not in december.

Cheers
Mark