Bosch e-drive moving speed sensor

[Otto Jæger]

Hi

I'm new to e-bikes, new to the forum, but have some understanding to electrical cucuits

I've just bought an Merida with a 250 W motor and 400 W battery for my wife. I do lot of cycling on my race bike, but would like to ride together with her. I do mostly train around 29 - 31 kph, but the Merida does only 25 kph.

I've been googling a lot to see if I could find a simple solution to the problem, and I've seen different dongles which "cheat" the electronics. Takes away every second pulse ?

I've tried to move the speed sensor to the crank-arm, and it almost works, but it is not stable, turns on/off. I know Bosch did some "adjustments" to the controller f/w in 2012, which made this impossible.

BUT: Does anybody know why it shouldn't work to move the speed sensor/magnet, and let the crank arm give the (slower) impulses?

Thanks,
Otto
Norway

 

[SRS]

Bosch programmed the system to error if it saw pulses at the same frequency as the crank rotation. Allows you about 30 seconds before it errors.

 

[Deleted member 4366]

It has a separate crank-speed sensor. They probably added a procedure in the software to compare the wheel speed with the crank speed. It might work if you can find a way to get two magnets on the crank diametrically opposite each other. You'd need to fabricate something to attach to the crank. Could you get the sensor close enough to the chain-wheel with a couple of magnets glued to the back of it?