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Discussion Starter #1
hi guys, i replaced the speed clock from my bike and got one of this
Street Bikes at Trail Tech Home

so to compare the speed and test it i went for a spin with another guy to compare his speed with my one. he was doing 120km mine was 110km thats a big difference. ive been trying to compensate.
after new calculations i went to try it and compare with the sat nav. and the clock is bang on with the sat nav speed, only drove it up to 120kmh
how accurate are the sat nav?
when i drive it in the car 120km on the car is 111km on the sat nav.

could some one please give me the diameter of the front wheel?

thank you
 

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diameter=16"+2*tire width*profile aspect
Or you could put a mark on your front tire, roll the bike till the front wheel rotates once, measure the distance on the ground, then:
diameter =square root of (circumference*4/pi)
 

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Discussion Starter #3
thank you for the reply. ive measure by the height of the wheel, gived me 1800, measure by rolling 1810 and done by distance draw a line on the ground drove the car with sat nav for a few km car was 3.2km sat nav 3.3, and the new clocks on the bike 3.4. this is driving me mad.
the bigger the diameter means she clocks faster or slower?


thanks again for you help
 

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after new calculations i went to try it and compare with the sat nav. and the clock is bang on with the sat nav speed, only drove it up to 120kmh how accurate are the sat nav?
when i drive it in the car 120km on the car is 111km on the sat nav.
could some one please give me the diameter of the front wheel?
thank you
What size tyre are you running?
For accuracy you need to measure the circumference of the tyre and it must be at the correct pressure.
Calculated circumference for the 130/70-16 is 1849mm.
 

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the bigger the diameter means she clocks faster or slower?
A larger diameter tyre will make the speedo read lower than your true road speed. The speedometer is merely "counting" how many times the wheel rotates per second. A smaller circumference tyre will rotate more times per kilometer than a larger circumference tyre.
 

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Discussion Starter #6
What size tyre are you running?
For accuracy you need to measure the circumference of the tyre and it must be at the correct pressure.
Calculated circumference for the 130/70-16 is 1849mm.


thank you. thats my tyre size 130/70-16
i measured it in 2 different ways and never came close to 1849.


ye are a really helping bunch

thank you very much
 
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