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Speedometer ´error´

  • <i class="fa--xf fal fa-check "><svg xmlns="http://www.w3.org/2000/svg" role="img" aria-hidden="true" ><use href="/data/local/icons/light.svg?v=1758297946#check"></use></svg></i> Discussion starter Discussion starter Petrus
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Petrus

Well-known member
Joined
Jul 18, 2025
Messages
727
Location
Vva. del Rosario - Málaga - España
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Bike
R18, Nimbus Type C sidecar, Vespas
Yes, another one.

Yes, used the search engine.

As all I get are a older hence a new thread.

Flogging the bike down the local pass the speedometer read 195 km/h.

I know the speedomete by law reads fast with quite bit of margin to compensate for variables.
Also the bike is limited to 180 km/h.

My comment is the rear tyre being bias ply. This means the diameter is subject to increase under centrifugal forces. Meaning that if the software instructions are a linear % (+5 km/h or so), then at top speed the speedometer is more accurate than at 100 km/h :ROFLMAO:
Stands to reason as otherwise 180 km/h plus 10% plus 5 km/h would be 203 km/h indicated.

Btw this is only half serious as top speed speedo accuracy is a bit of a moot subject on a large cruiser 🫣
 
It can always get worse. My speedometer didnt properly reference and was therefore around 40km/u off. (Due to a bad battery)🙃
 
My speedo is 10 percent out. Which I think is more "outright wrong" than simply "margin" That would make your 195 top a more realistic 176. Try it again with a gps speedo app on your phone?
 
I will for súre thunder down one of the empty highways one day just to try and see how far the the needle on the speedometer climbs up.
I will trý install an app on the handy and gps the speed although the real top speed is not of much interest to me other than a nice to know.
What doés spark my interest is the app potentiallial registerimh bothe the speedo ´error´ and the tyre growth.

First need the weather to dry and meanwhile find/install an app :unsure:
 
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