Few issues

[Calhoon00]

Hi all, I bought my Emtb out of china Alibaba, it seems to have decent specs, but, it stripped the rear sprocket, I upgraded the chain and a new rear cassette with a different ratio hoping this will not do the same again.but now my speed reading is out by at least 10-15km/hr, and because it is new Canbus cable, I don't know how i can reprogram, everywhere I read it seems it's not possible, I'd really like to know how..
Would also like to know who's frame base they have used..
Thanks all if anyone can help..

 

[harryS]

Are you sure the speedometer is off or is it that you have a different top speed because you have a different gear size for the smallest one?

Simplest and most accurate way to get speed is to get the wheel rpm from a speed sensor and convert that to speed, knowing the wheel diameter. Determining it from knowing the motor rpm and what current cassette gears are being used, plus wheel diameter, seems unnecessary to me.. DOes the bike know what gears you're in?. Then I suppose you have to set up the ratios.

 

[gromike]

It looks like he has a speed sensor on the rear wheel, as would be expected. So, changing the cluster shouldn't affect his displayed speed.

 

[Gionnirocket]

It looks like he has a speed sensor on the rear wheel, as would be expected. So, changing the cluster shouldn't affect his displayed speed.

I concur.
The Ultra uses a spoke mounted magnet and chainstay mounted speed sensor. Changing the drivetrain has no affect.