Speedo question

[darwin]

Speedometer - Odometer App - Apps on Google Play

GPS Offline Speedometer tracks speed, distance, time, km/h, & mph on the map

play.google.com

 

[Sidewinder Jerry]

Speedometer - Odometer App - Apps on Google Play

GPS Offline Speedometer tracks speed, distance, time, km/h, & mph on the map

play.google.com

Most of these GPS apps simply aren't accurate enough to remark an analog speedometer. To accurately remark the analog speedometer the bike can't be moving. Which is why I suggested the tachometer method. Hopefully, there may be a calibration adjustment on the analog speedometer.

 

[Cannonball3]

You can use one of the better bike computers to cross check the analog. I have found them to be quite accurate
if you roll the wheel to get the tires circumference. I ran one on my BMW K100RT to use as an odometer as the stock odometers were known to fail(speedo still worked). After entering the circumference it was basically right on with the BMWs speedo. Using the common 26” setting is close but tires vary a good bit even ones of the same size.

 

[Sidewinder Jerry]

You can use one of the better bike computers to cross check the analog. I have found them to be quite accurate
if you roll the wheel to get the tires circumference. I ran one on my BMW K100RT to use as an odometer as the stock odometers were known to fail(speedo still worked). After entering the circumference it was basically right on with the BMWs speedo. Using the common 26” setting is close but tires vary a good bit even ones of the same size.

I take a true diameter measurement. My fully inflated 26" Kendra 838 tires are 26.25". I then enter that number into my Sigma 14.16 bicycle computer.

The blank-faced analog speedometer and a bicycle computer would then have to be temporarily hooked up to the rear tire to get the 5 mph increments to mark on the blank face. So you're right a bicycle computer or tachometer could be used to remark the analog speedometer.