Bafang BPM 350W Front Motor opinions

[Alan Quay]

Hi All,

Can anyone give any opinions on the above motor that I have tentatively selected for a project for a friend. I plan to use the 201 rpm/36v version and run it with a 36v/20Ah Li-Ion battery via a 450 watt controller. It will be installed up front on a mountain bike with 26" wheels and disk brakes.

Predictions of top speed, and thoughts on hill climbing ability would be helpful.

Thanks in advance.

 

[amigafan2003]

They are strong motors, especially on a 450w controller. Top speed with a 201rpm motor on a 36v battery should be around 16mph no pedalling. The battery should be able to handle the amp draw.

What forks will you be fitting them to? If the forks have allow drop outs you need to be REALLY anal about getting a perfect fit so as to not crack the drop outs and experience a face plant scenarion.

Best option would be fit them to steel forks.

 

[Deleted member 4366]

201 rpm is a code 15 and it'll do 15mph, which I think you'll find a little slow. It'll actually do about 17mph with a fully charged battery if you're lucky. The code 11 or 12 are much better and will give a rel-world speed of about 20 mph. If you're planning to get from BMSBattery, they won't tell you which code number you'll get. You have to wait for the surprise when it arrives. It could be anything from code 17 (very slow) to code 11. Other suppliers should be able to give you the code number.

If you get a code 15 36v and run it at 48v, it behaves as a code 11, so you can order the motor and controller first (get a dual voltage controller) and if the Code number is high, get a 48v battery, if low, get a 36v one.

You need at least one good torque arm on the forks. Two is better, and they need to be properly installed. You can use the disk brake fixing on one side, but you need to be a bit more creative on the other.

Have a look at the forks to check that the drop-outs are nice and thick and have a bit of meat around them as well. I''ve seen some that I wouldn't want to put any hub-motor in. Rockshox and Fox are normally OK.

450w controller doesn't mean anything. What's important is the maximum amps it will give. Unless you like to pedal hard, 22 to 25 amps is about right for this motor in the front.

Hill-climbing is very good compared to a 250w hub-motor, but for serious hills, the 500w rear version is better. Why have you chosen front over rear? It's much easier to install in the rear. Although a bit more expensive, the 500W CST with cassette spline is the easiest of all. It just slots in with a single torque arm on the disc brake fixing, the battery and controller in a bag tucked in behind the seatpost, and away you go. Remember, if you have high power, you can always turn it down, but if you have low power, you can't turn it up. The 500w motors are the same size, weight and price as the 350w ones, so I don't see an advantage of the 350w ones unless you want lower power for a front motor. I wouldn't fit a 500w motor in the front.

I know I keep going on about it, but Saneagle's Kraken conversion is the best conversion I've seen. It's poweful, smooth, quiet, stealthy, and has long range. Here it is behind mine. We both have the same motor and battery:

 

[Kudoscycles]

Dave/Mike.
I have just been advised by Bafang that the CST motor is now available max 350 watts,if you want 500 watts it must be BPM.
Interestingly if you are sticking to 250 watts they recommend the CST over the BPM.
KudosDave

 

[103Alex1]

Dave/Mike.
I have just been advised by Bafang that the CST motor is now available max 350 watts,if you want 500 watts it must be BPM.
Interestingly if you are sticking to 250 watts they recommend the CST over the BPM.
KudosDave

18 left at BMS Battery. Rear hub motor only.

Bafang 36V500W CST Rear Driving Hub Motor - BMSBATTERY

 

[Deleted member 4366]

Xofo, MXUS and another make cheaper clones, so there''ll still be plenty of options.

 

[Alan Quay]

Dave/Mike.
I have just been advised by Bafang that the CST motor is now available max 350 watts,if you want 500 watts it must be BPM.
Interestingly if you are sticking to 250 watts they recommend the CST over the BPM.
KudosDave

OK, that changes things again, thanks for the info.

D8veH:

Went for a front as I like the balance, and I also the like the 'all wheel drive' element, however, I think you might be right about a rear being easier.

Interestingly, MY bike has no torque arms, and an alloy fork (Suntour XCT). It does have some heavy washer type things - each with a lug that protrudes into the drop out. I assume they act in a similar way. Does this mean that my forks are at risk of cracking?? To be fair, they have been OK for the last 500 miles or so, but I'm a bit worried now, having recently changed battery to a Li-Ion 20Ah which as improved performance a fair bit.

My motor is (I think) a Cute 500w. Its at least 3 years old, possibly older. Its not great at hills, but unloaded will spin at around 270 RPM.

 

[Deleted member 4366]

If it's the Q128, it's over-rated at 500w. I found that the smaller Q100 gives about the same torque and power. So, to answer your question, you don't really need torque arms with it, but the wheel-nuts need to be done up tight. Those anti-rotation washers still transmit a large force to the drop-outs. What aluminium doesn't like is cyclic forces. Eventually it work-hardens then cracks, so you have to be careful. The more you can spread the load, the better, and properly installed torque arms hold the axle in place if the drop-outs do break, which prevents you going head first over the handlebars and doing a face-plant.

 

[Deleted member 4366]

Dave/Mike.
I have just been advised by Bafang that the CST motor is now available max 350 watts,if you want 500 watts it must be BPM.
Interestingly if you are sticking to 250 watts they recommend the CST over the BPM.
KudosDave

Seeing as they put a 250w marking on the 350w motors, they must be putting 350w labels on the 500w ones.
I just had an e-mail from Xofo reminding me about their motors. They don't appear to be ceasing production of their 500w one, and I'm sure they''ll put a 250w label on it, which saves a lot of messing about.

 

[Alan Quay]

Thanks for the reassurance about the forks, and it is interesting to note that the Q128 is over rated. I'm pretty sure its a Q128 now I've looked it up, and D8veh's results confirm my gut feelings about it.

I think that the suggestion of a rear CST (be it 350 or 500 watt) is probably what I will put to my friend, and then he will have better bike than me, dammit!

Thanks for the advice chaps, as always much appreciated.

BTW D8veh, the dog says hello

 

[Deleted member 4366]

Say hello back for me.

BTW. He said that he prefers McVities chocolate chip cookies, not the Sainsburys ones.

 

[jackhandy]

I don't know if the chap who'll be riding this is of similar, sylph-like, build as yourself, Mike: If so, he might hold down the front end better than I do mine

I find my 8fun 250w front motor skips about quite a bit on loose-surfaced uphill sections, so I'd imagine a bpm/cst would be a tad lively.

 

[Alan Quay]

JackHandy,

Haha, I tend to create a fair amount of down force, so lack of grip has never been a problem. I've moved over to schwalbe Fat Franks and rarely lose grip even on up hill gravel tracks.

All that said, I'm convinced to go RWD for this build, if only so I can do donuts while testing!