speedometer ratio

[vasilegrigore]

I have a honda cb500 1997 and looking to change its speedometer.
Looking to get something like this.
https://www.classicbikeshop.co.uk/speedometer-black-face-late-type.html
Simple and clean.
But the ratio gets me confused. it says ''Drive Ratio 2:1.''
Any ideas ?

[Easy-X]

Basically how fast is the cable that feeds into the speedometer rotating? Something along the lines of: bike doing 100mph, cable is spinning at 50mph...

Unfortunately, AFAIK most Hondas are either 7:1 or 4:1.
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[MCN]

As long as the original fit it 2:1 it will be ok.
(Providing that you can determine the original fit ratio. )

The spec for that 'should' be available online.
Need to sharpen your Google pencil.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[WD Forte]

Hang on a mo
what size wheel?
Ratio aside, a small scooty wheel will spin a lot faster at say 30mph
than an 18" MC wheel so the pulses/revs wil change in relation to that.

Most old type speedos are designed with overall diameter in mind and the impact the pulses/revs will have on the flux capacitor type thing
that moves the needle against the hair spring.

You can buy gearboxes to alter the ratio of course but I never understood the point of throwing money at a speedo which isnt
particularly accurate anyway.

According to Teffers we have 5-1/4 turns per 365 degrees
divided by a pro rata compound interest of 1/6d per day
added to 8 furlongs per mile plus an extra day in a leap year
so that makes it about one pound seventeen and sixpence.
or 30 bob if you take it on a 2 year contract.
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[vasilegrigore]

Well my intention is to buy a simple speedo. No LEDs no indicators no nothing.
With that in mind, the advertised speedo looks perfect.
On the website they have same speedo with 3 ratios:
1.25 - 1 -> https://www.classicbikeshop.co.uk/speedometer-1-25-1-mph-black.html
1.25-1/ 15-12 -> https://www.classicbikeshop.co.uk/speedometer-black-face-mph-ratio-1-25-1-15-12.html
2 - 1 -> https://www.classicbikeshop.co.uk/speedometer-black-face-late-type.html
I'm assumed those 3 are standard which they are not apparently.
Don't know the ratio on my Honda, as if I knew, I'd just buy it

[WD Forte]

https://www.hondatwins.net/threads/speedometer-tachometer-ratios.131542/

Read the whole page for corrections
The main ones are there are 2240 turns per mile which
applies to the odo accuracy
and the reduction ratio is 2.75
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