Barfang 8fun 250w mid drive help

[Derek M Walshaw]

After all the good reviews I've just moved from a 250w 8fun hub drive MTB to a 8fun 250w mid drive. I'm not sure if I have a duff one. How are you suppose to ride these things. With the hub drive it was simple. go up hill motor struggles add more assist or take it up a cog. Press hard into pedals motor gives it back. I have had 2 mid drives and both did the same. no matter what assist level, if I pushed on pedals hard to help motor the power the power goes to zero. to keep the power on I have to turn the crank with a high cadence and not press hard on the pedals. If I'm going op hill over some rock steps and need a push harder just to get that momentum, the bloody power cuts out on me.
Any help would be appreciated please
Cheers Derek

 

[Nealh]

Gearing is critical for climbing you have to be in the lowest gear that is comfortable with good cadence other wise you will find your self stalling, treat the crank drive as you would a normal unpowered bike when climbing. They give very good torque in low gear and this is when most amps are likely to be drawn but need a lot more leg work then hub drive.
Which battery are you using and its condition as it sounds that as you ask for more power/amps the battery isn't able to deliver,

 

[Fordulike]

The problem with the Bafangs is that they are quick to cut the power from the pedal assist, but quite slow to reapply the power. It only takes a momentary stop of the pedal (or back pedal) for power to cut to the motor. Then to make matters worse, it can take about an eighth of a pedal revolution to kick the power back in.

This makes it difficult to negotiate technical terrain, as the power can stop when you need it most, and by the time you've realised you need to start pedaling again to reapply power, the bike has come to a standstill.

One solution is use of the throttle to apply power in situations where the motor might cut out.

The throttle will help on hills too!

The controller can be reprogrammed to adjust the bike to suite a rider's particular riding style, but does take a bit of technical knowledge and insight into how the controller integrates with the motor.

 

[Derek M Walshaw]

Thanks all for the info. Is cutting the motor some kind of protection? My battery is an 11.6v and the controller is 16amp. What it sounds like is, the motor is good for the roads & smooth trails, but when it come to the rougher stuff its found wanting. I will use the 8fun for that purpose. Can the cadence speed be reset to a lower one/
Thanks for the help

 

[Fordulike]

Thanks all for the info. Is cutting the motor some kind of protection? My battery is an 11.6v and the controller is 16amp. What it sounds like is, the motor is good for the roads & smooth trails, but when it come to the rougher stuff its found wanting. I will use the 8fun for that purpose. Can the cadence speed be reset to a lower one/
Thanks for the help

You probably mean the battery is a 36v type, and I believe the controller has a max amp output of 15 amps.

The motor should be running as long as the pedals are turning. It is designed to stop when you stop pedaling, or the brakes are applied, for safety reasons. Also it helps prevent damage to the motor and drivetrain.
If your motor is cutting out whilst the pedals are turning, you have other issues.

AFAIK, the cadence control cannot be changed, but other parameters can, such as power delivery in each of the PAS levels on the display.

These parameters can only be accessed and changed with a controller cable, PC or laptop, software and a little knowledge of how it all works.

Most of the Bafang units, whether BBS01 or BBS02 come programmed with limited max amps.

For example, you might think your BBS01 has 15 amps x 36 volts = 540 watts available.

But in reality, they are usually factory programmed to limit the amps to 60% of what they have stamped on the unit. See 'Keep Current' referenced on page 3 of the following link:

http://www.emax-ebikes.com.au/uploads/3/7/4/4/37442009/programming_bafang_bbs.pdf

So in your case, 60% of 15 amps would equate to 9 amps x 36 volts = 324 watts available.

I can understand why people might buy these units expecting a bit more oomph, but end up feeling a little disappointed.

 

[Geebee]

Lower your gearing and keep the cadence up, with the correct gearing they will climb any hill without rider input added.
The biggest issue is that the default gearing supplied is better suited to a 20" wheel than a 26" if in hilly terrain, fit the smallest chain ring you can.