As the title says... will putting a smaller sprocket on cause your odometer to spin mileage more quickly? This happens on cars when you change the rearend differential gearing. Just wanted to know if my mileage is adding up faster than it should be, and if so, how much more quickly?

 

Yes it will. From factory, sport bikes read around 5% high in the first place so you're already racking up mileage. Changing the gearing will add to this error. For $100 you can buy a speedohealer that will let you correct this.

 

Thanks, I found the speedo healer on Ebay and ordered one. Now to discover what all is involved to get it setup right.

 

This causes only one real problem... resale value. And if your patient enough to wait for someone who actually knows something about sportbikes to buy your bike, they will actually believe you when you say the odometer is 10% high since x,xxx miles.

 

Set up is easy. It's plug and play on the item itself and the website does the math for you. I use the two speed comparison method. I ride my bike with my GPS suctioned to the tank to compare the speedo to the real speed. Then you type the numbers into the website and it tells you to steps to program. PM me if you have problems.

 

you are forgetting one main thing. from the factory, the speedo is off but the odometer is correct. changing your gearing and then installing a speedohealer will calibrate your speedometer, but your odometer will now be off. from the speedohealers FAQ (http://www.speedohealer.com/eng/faq.htm):

5. Will the SH calibrate both my speedo and odometer? Yes, but it is not possible to calibrate them separately, as one speed signal drives both the speedometer and the odometer. You can get 100% accurate speedometer AND 100% accurate odometer only on those bikes, which have zero "speedo-to-odo" error ratio (see FAQ #16) built-in, such as the Yamaha FJR1300. On most bikes, if the speedo is calibrated to be 100% accurate, the odo will register slightly less miles. While this can be annoying in certain situations, one can always calculate the real distance easily after a long trip. Alternatively, of course, you can get the factory default indication regardless of the used sprocket ratio: accurate odometer and slightly optimistic speedo. With our on-line calculator, you can optimize the calibration value easily for either speedo or odo.
16. What is the "Speedo-to-Odo error ratio"? There is one speed signal which drives both the speedometer and the odometer. However, the manufacturers make the display units such a way that the speedometers usually read high, while the odometers are quite accurate on stock vehicles. Speedo to odo error ratio is the quotient of the indicated speed, and the speed which drives the odometer internally. This error ratio is fixed in the dashboard logic, i.e. it's bike model specific and will be constant no matter what you change on your bike. The speedo to odo error ratio is almost the same as the initial (factory) speedo error, considering that the odometers are usually accurate on stock vehicles.

i would still recommend one though. i just got one and its much better (i was 10.5% off from my re-gear)

 

So, what you are saying is the odometer from factory is correct, but the speed is off? I did not know this. If both are not off, then why are they not able to correct this? I was assuming if the speed is off, the odometer is off.

 

Thats correct. While I'm not sure exactly why they set the speed high, I think it's because they know that most people are going to drive their bikes fast, so if they think they are going 75 but they are actually doing 70, its "safer."