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NT Inaccurate speedometer

Discussion in 'Politics, Laws, Government & Insurance' at netrider.net.au started by Woza98, Oct 28, 2014.

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  1. #1 Woza98, Oct 28, 2014
    Last edited by a moderator: Oct 29, 2014
    So recently I downloaded the Diablo Super biker app which records trip top speeds, average speeds lean angles (with questionable accuracy IMO) and various other statistics. You can then look back at precise points of your journey to see what your speed was.

    I initially noticed a discrepancy when I went to 100KM/H and looked at the result. My bike speedo wrote 100 exactly when I finished accelerating but once I reviewed the app it only read a top speed of 91. Upon further testing I have found roughly a 10% decrease in "real" speed when compared to the speedo.

    I am a bike newbie but I have heard that it is natural to have a not entirely accurate speedo because only the front wheel is being used to devise the reading. However >10% just seems way to much. Can this be fixed during a service? My bike is just coming up on 14,000 KM which is 2nd service increment for my bike I think.

    I am fairly confident that the app is accurate because my friend who owns a Ninja 300 is only 2-3 KM/H off at the most. The reason I say the lean angle is off is because of it's questionable recording methods and the fact my friend on a ninja 300 managed to get a reading of 54 degress... thats so MotoGP level shit.

    Any advise would be helpful. I would recommend getting the app if you haven't already, its pretty cool.

    <mod-edit> J - Your thread was not created in the correct forum. Forum search "speedometer" (y)



    https://netrider.net.au/threads/vicpol-safety-first.175032/page-4#post-2688418

    https://netrider.net.au/threads/reduced-tolerance-for-speeding-drivers.157266/page-2#post-2601910


    https://netrider.net.au/threads/truck-turning-illegally-caused-me-to-fall-off-bike.146416/page-3#post-2535729
     
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  2. Most vehicles have some discrepancy between real speed and what you're reading on the speedo and ten percent error is not unusual. As long as your 100 is actually really LESS than 100 you should be safe.
     
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  3. So with regard to the lean angle...was the phone flopping around in his pocket at significantly more of an angle than the bike??

    A phone is a phone, not some accurate racing data acquisition/telemetry device....not even a good phone in the case of crapple, imho

    Can an inaccurate speedo be fixed...be careful what you wish for....different tyres have different circumferences, there is even a measurable difference between a new tyre's and a worn tyre's circumference.
     
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  4. As Hornet said, a discrepancy is quite common. The Australian standards allow speedos to read over the actual speed by more than you'd expect but little to nothing under. It's handy in that you're unlikely to be done for speeding if you stick to the limit as shown on your speedo, but then you'll also be travelling slower than other traffic.
    The speedo in my DL reads about 8-9% high. It's a known "thing" with them. If you want to know for sure check your speed with a GPS.
     
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  5. Yeah the speedo on my bike would be out by close to 10% over.
     
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  6. Another 10%er here.
     
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  7. The speedo on my Z1000 was out (reading over) by approx 3%. I changed the rear sprocket, went down form a 42 to a 41, now the speedo is within 1%. When showing 100 on the speedo, shows 99 on the GPS. And yes my bike reads the speedo of a sensor in the gear box, hence the difference from changing the rear sprocket.
     
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  8. Changing tyres will effect this too.
     
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  9. 7% on both my Hondas. Was 7% on all my previous Suzuki's too. The odo will be pretty accurate though.
     
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  10. Agreed, If I ever fit a 55 series (As has been recommneded to me) over the standard 50 series, that may be enough to put my speedo out by reading under. But each time I change tryes I check the speedos accuracy with a GPS.
     
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  11. Tyre pressure also affects speedo accuracy.
     
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  12. Vstroms are notorious for having speedos reading about 9% out. I know that 500 rpm = 10 km/h so that 5500 rpm is 110 km/h on the road. The speedo says 120. I just live with it.
     
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  14. The faster you go, the more the discrepancy changes. I've ridden with a GPS and when the speedo showed 250kph, the GPS said 230kph. Thats about 8% error. A bit disappointing, but again at least the error is on the right side.
     
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  15. As noted, 10% optimism is not at all unusual. A variation of 2% or so will also occur over the life of whichever tyre provides the reading, due to wear.

    Although theoretically possible, I've never seen a speedo that underread on a standard vehicle, only where wheel sizes, gearing or speedo head or drive had been changed.
     
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  16. Oh god. Are you new to cars too? You'd be amazed how many people you pass when you travel at the speed limit
     
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  17. #17 oldbloke43, Dec 31, 2015
    Last edited by a moderator: Jan 5, 2016
    "Should be safe"?? The Australian design rule for bike speedos is a farce. It allows an error that is quite significant and at the extreme, your speedo could indicate 110 kph on th M1 (the speed limit over most sections), while you are actually traveling at 93 kph, or in a school zone, your speedo could be indicating 40 kph while your actual speed could be only 29 kph. Now if you are being really good and riding at an indicated 5 kph below the speed limit, you are really looking to be shunted from behind. Safe???

    A very cheap and accurate solution is to fit a cycle speedo. Make sure you get one that reads to "999" and not just "99". I have fitted a Cyclo Velo 7 to my R3 Yammy (speedo error around 9%) without any permanent mods to the bike. I can not only programme this speedo in 1cm change in tyre circumference, but also now have another trip meter/clock/max speed etc readouts.
     
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  18. I installed a Healtech Speedohealer on my VFR.
    It was previously linearly 10% out, compared to a GPS.
    Now it is spot on at any speed I've had it at.
     
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  19. I have set my cycle speedo to read around 1% high and am so happy with the results that I have fitted the same cycle speedo to my Kwakka road/trail bike, so I now have a trip meter as well. An economical and accurate solution for around $27 AU from ebay.
    It must be time for the design rule to be changed (last change was 2006), the technology is certainly available.
     
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  20. All speedo variances are within the manufactures tolerances, in other words don't bother talking to your dealer about it, mine is 3kms slow at 50 km and 8 kms at 100km
     
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