speedometer inaccuracy

Discussion in 'The Workshop' started by sean178, Nov 11, 2017.

  1. sean178

    sean178 Active Member

    Messages:
    181
    Right. I downloaded a GPS tracker on my mobile today and went out on my fmr50.
    I've been riding into our village and the little speed warning sign flashes up 30 when the bike tells me I'm doing 40.
    So I hit 80kmh on the speedo but the GPS logged a top speed of 60kph. I understand that scooter speedos are never going to be accurate but that's a big difference (Yes, I know, cheap Chinese scooter !!!)
    So Im wondering if, when I need some, slightly bigger tyres would bring the speedo accuracy a little closer to the actual speed ???
     
  2. scubabiker

    scubabiker NITROJUNKIE

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    7,321
    Speedos are always off, even my bmw has an inacurate speedo...
     
  3. Mark Emerson Trentham

    Mark Emerson Trentham Well Known Member. Staff Member

    Messages:
    8,556
    Rides:
    NSC110/ ET2.
    I'm quite thankful my speedos have been inaccurate in the past - considering some of the crap i've ridden.;).
     
  4. sean178

    sean178 Active Member

    Messages:
    181
    Fair comment, but I bet the Beemers isn't 20kph out, and I know we are comparing German engineering to Chinese mass production. What do you think to the (slightly) larger tyre idea Scuba ??
     
  5. daveNRGdt

    daveNRGdt Member

    Messages:
    49
    If it really bothers you, you could mount an aftermarket GPS Speedo to your handle bars. You can get them fairly cheap from Chinese sites like aliexpress. Larger diameter tyres will bring your speedo discrepancy down a little but it's not going to be perfect. Are the tyres currently fitted the manufacturer specified size?
     
  6. sean178

    sean178 Active Member

    Messages:
    181
    Yes they are, and a GPS was how I measured the 20kph discrepancy, now I know how far out it is I have an idea of the speed I'll be travelling compared to what the speedo says
     

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