Bafang BBS02 resistance

[rccarguy]

I've fitted a Bafang BBS02 e bike kit to a bike, with it switched off (battery went down to 15% 5 miles from home so I didn't want to continue using battery) there is a fair amount of resistance using it as a normal bike. It's fair amount, if feels like brake is partially applied, it's like a turbo trainer on lowish setting.

It was really hard work pedalling, especially up a hill. I've carried weight equal, if not more than the battery and motor and it was far easier than this.

The bike was fine before the conversion . Rotating cranks with the chain off feels ok. The front and rear wheels spin freely. It feels like you are turning something inside as not only resistance but some kind of gear meshing feeling/noise, it's not simply turning the crank and 100% power going into the chain.

Also with the Bafang it pulls away fine with the motor but after say 10mph it switches off, and only if I use a higher PAS setting does it keep assisting to a higher speed, so if feels a bit blippy in use. But then at a higher setting it is a bit too aggressive in speed, and it's probably too much battery drain. Computer shows mph fine. It's a new ebike kit.

Is this normal?

 

[harryS]

Mine doesn't act that way. It's a 2016 model. No resistance when power is off, Slip off the chain, power off the BBS02, and see if there's any drag on the crank. Should not be any. See if wheels spin freely.

ARe you set for 9 level PAS or the default 3 level or 5 level?

 

[tomjasz]

Sag? How old is the battery?

 

[rccarguy]

If I spin crank it rotates about one rotation compared to 10 on another regular bike

Resistance seems greater when actually riding.

New conversion new battery

 

[AHicks]

If I spin crank it rotates about one rotation compared to 10 on another regular bike

Resistance seems greater when actually riding.

New conversion new battery

Huh??

The question is when you turn the crank, is the motor turning as well? Can you feel the "cogging" caused by the motor's magnets when turning the crank in the forward direction?

If that's the case, it's not right.

USUALLY, when somebody is talking about resistance while pedaling, it's because the motor is spinning when there's no power going to it. That's going to create a LOT of drag and it's wrong. There is a clutch that should release, allowing the motor to stop when there is no power going to it.

 

[rccarguy]

I've taken a couple of videos.. uploading now. If the clutch is faulty woukdn't it mean when the motor is active the chainring will spin also?

 

[rccarguy]

Watch oucn61 | Streamable

Watch this video on Streamable.

streamable.com

Watch 6epthg | Streamable

Watch this video on Streamable.

streamable.com

 

[AHicks]

You are on the wrong track with that comparison. There is WAY more drag on a mid drive in the scenario/comparison you are using. Still, that mid drive drag should be barely noticeable when you are out riding.

 

[rccarguy]

btw the friction doesn't seem to bad on the video but when riding it's much worse, it does literally feel like you are applying brake, going up a hill

 

[harryS]

That video is like mine. One+ turn in fwd pedal direction with no chain. No comparison with a normal BB which "spins forever." If power is on, spinning the pedal w/o chain still activates the cadence sensor, and the motor starts up.

I've ridden often w/o power in PAS 0, but my throttle is always ON. so I can feather it in. I didn't think the motor was dragging.

Good tire pressure? SOme engagement of brakes with weight on bike?

 

[rccarguy]

Tyre pressure ok and no brake rub

I'm a bike tech

 

[harryS]

Well, maybe you can feel stuff that us duffers don't feel. Someone used to a 20 lb bike would say my BBS02 conversion is like a truck, and it probably is to someone used to a very expensive road bike. A lot of ebikers are riding 70+ pound trucks.

 

[rccarguy]

Is the throttle variable because it feels on/off. The only way to make it variable is to change Pas.

Ie if I put full throttle on Pas one, then keep throttle at full changing to Pas 2 increases speed.

It would make sense throttle bypasses all Pas settings

I don't use throttle as illegal plus it doesn't fit on the bars

Is gear and brake sensor (inline) worth it? Drop bar so the brake sensor looks like the gear one

 

[AHicks]

btw the friction doesn't seem to bad on the video but when riding it's much worse, it does literally feel like you are applying brake, going up a hill

Being a bike tech, you should appreciate the difference in bearing designs and preload. If you went into this with the idea that this conversion was going to pedal and roll as easily as a conventional bike it's easy to see why you might be disappointed.

As far as the conversion's crank spinning, convert a conventional bike to the size and type of crank bearings necessary to handle the power of the conversion. Now add the drag of a clutch to that.

Re: brake sensor. That's kind of a safety issue don't you think? Your ace in the hole if something goes haywire?
Re: gear/shift sensor, if you've been riding a bike that requires you to shift for a while, to the point where you unload the stress on the gear train without thinking about it, then no. You don't need one.

 

[c3strom_echo]

The bearing of the regular bicycle is different from the bearing of the mid-drive motor.
here I took a small video of 3 kinds of motors, showing the speed of different bearings:

• Bafang BBS02B 750w mid-drive motor;
• Bafang New M625 1000w mid-drive motor;
• Regular e-bike with rear 500w hub motor.

The bearing smoothness of the hub motor is a little better than that of the mid-drive motor，
but it's only a little bit, far less smooth than ordinary bicycle bearings.

Watch different motor | Streamable

Watch "different motor" on Streamable.

streamable.com

 

[rccarguy]

Will these fit on road bike drop levers?

brake sensor-2 for 8fun/bafang center motor/middle drive motor kit | eBay

Find many great new & used options and get the best deals for brake sensor-2 for 8fun/bafang center motor/middle drive motor kit at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

 

[AHicks]

I hadn't seen that type before, but they look like they would work fine to me.

 

[c3strom_echo]

Will these fit on road bike drop levers?

brake sensor-2 for 8fun/bafang center motor/middle drive motor kit | eBay

Find many great new & used options and get the best deals for brake sensor-2 for 8fun/bafang center motor/middle drive motor kit at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

yes!

 

[tomjasz]

This type of cutout has been around for 6 years, at least. The linked are just another version of the original IME.

 

[tomjasz]

Will these fit on road bike drop levers?

They use the brake cables to send a cutout signal. Nothing to do with the type of levers. You feed your brake cables through them. The movement when braking cut out the motor.