Bafang bbs02 48v 750w shaking on high PAS and on high gear

[arar1971]

hello,
I built my second e bike with Bafang bbs02 48v 750w kit ordered from BTN aliexpress on 11.11.2014 sale. I am trying to getting used to it. riding and shifting is different than hub motors. hubs like more riding bike. bafang mid drive feels more riding bicycle.
but while I was testing it , I realized that on 6-7-8-9 PAS settings, on 6th or 7th gear, when the speed is low and try to accelerate, the bike starts shaking back and forth til reaches to optimum momentum. is it normal ? anybody having same thing? why it makes like that? is there a problem with it?

Any help would really be appreciated before the dispute time.
thanks.

 

[arar1971]

here are the photos of it:

 

[Warren]

arar1971

"on 6th or 7th gear, when the speed is low and try to accelerate, the bike starts shaking back and forth til reaches to optimum momentum. is it normal ?"

Yes. Riding in 6th or 7th is exactly like lacing your hub motor into a wheel 1.5 to 2 times as big in diameter as your normal wheel. How would you hub motor pull from low speed in a 40" wheel?

 

[arar1971]

then, you mean there is nothing to worry? But I have to be more fragile and carefull when gearing. it is my second day riding a mid drive and I have to understand its character to get used to it, before damage it.

arar1971

"on 6th or 7th gear, when the speed is low and try to accelerate, the bike starts shaking back and forth til reaches to optimum momentum. is it normal ?"

Yes. Riding in 6th or 7th is exactly like lacing your hub motor into a wheel 1.5 to 2 times as big in diameter as your normal wheel. How would you hub motor pull from low speed in a 40" wheel?

 

[arar1971]

Or can be a motor problem like phase wires, hall sensor ?

 

[KINNINVIEKID]

Lots of folk have reported the same symptons(known as "cogging") and its explained above.
Just like a car you have to be in the right gear at the right time.
Try setting off in your car in 4th gear and see what happens
You should always keep your motor spinning at a decent rev rate as it will produce less heat this way and make your motor(and battery) last a lot longer.
Main thing to remember is when you are going to stop always change down to a low gear first ready for pulling away again.

 

[wineboyrider]

This is where the experience of driving motorcycles come in handy, except with a bicycle you have to shift down before you stop...

 

[arar1971]

thanks for your replies.

 

[j8519]

The problem with the bbs so2 its that the motor needs a strong batery like 48v 20ah to 25 ah to run whell on any high gear