Rear hub motor recommendations for cycle courier bike

[vulcanears]

Hello everyone!

At the moment, my main job is to deliver food on my DIY ebike and I usually ride 80+ miles, 6-7 days a week in a rather hilly town (Brighton).
I'm currently using a Bafang G310 rear hub motor, but it's not really up to the task and I have to replace the internal nylon gears every few weeks. Now I'm looking for something more heavy duty.

Requirements:
- must have a 250W factory label to be street legal (please no 'noone cares, just get a 1000W and put a sticker on' recommendations)
- decent hill climbing ability
- good reliability and long-lasting
- easy to service, easy to find replacement gears
- freehub cassette (no screw-on freewheel)
- as powerful as possible, whilst still being UK legal

I can build wheels myself, so I just need the motor without spokes.

Thank you very much in advance!

 

[Hovlev2]

How about one of these/ http://www.topbikekit.com/akm100cst-cassette-36v250w-ebike-rear-driving-hub-motor-20283236-holes-p-728.html

 

[vfr400]

A Bafang BPM or CST would sort you out, but ones labelled as 250w are very few and far between now. There's one here, but it's sensorless, which isn't really a problem with these motors, except you might need a new controller, and the photo doesn't show the important code number on the stamping, so you have to ask the supplier what it is. Codes 10,111, 12, 13 would be OK with 14 being a bit on the slow side and code 9 being marginally too fast.

Bafang 8FUN Bpm Back Wheel Motor Hub 250W (JS-033 Bpm 250W) - New | eBay

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The AKM100 above wouldn't give you any advantage over what you have.

 

[WheezyRider]

Hello everyone!

At the moment, my main job is to deliver food on my DIY ebike and I usually ride 80+ miles, 6-7 days a week in a rather hilly town (Brighton).
I'm currently using a Bafang G310 rear hub motor, but it's not really up to the task and I have to replace the internal nylon gears every few weeks. Now I'm looking for something more heavy duty.

Requirements:
- must have a 250W factory label to be street legal (please no 'noone cares, just get a 1000W and put a sticker on' recommendations)
- decent hill climbing ability
- good reliability and long-lasting
- easy to service, easy to find replacement gears
- freehub cassette (no screw-on freewheel)
- as powerful as possible, whilst still being UK legal

I can build wheels myself, so I just need the motor without spokes.

Thank you very much in advance!

Did you sort a solution to this? I think the key thing you need to look for if you are moving loads around is the amount of torque the motor can provide.

The G310 only has an advertised torque of only 30 Nm, and in reality it's probably a fair bit less than that:

Component

Bafang description

www.bafang-e.com

So I can image that it's struggling. I'm currently using an RM G020250DC, which works ok for me (rated torque 45Nm), although I would say for me it does not seem to give as much torque as my old SWX02 did, which was also supposed to be 45Nm.

Components

Bafang description

www.bafang-e.com

What might be nice is to try the G040250DC, it's torque is rated as 60Nm:

零部件

Bafang description

www.bafang-e.com

However, if you are building a DIY bike, you could have wide forks and go for something like this, a 175 OLD motor, which is still 250W rated, but has an advertised torque of 80 Nm:

零部件

Bafang description

www.bafang-e.com

Other ways of increasing the torque of your existing motor are to try and increase the amps from the controller, or increasing the voltage you are using.

 

[WheezyRider]

It's interesting you mention the nylon gears stripping in your G310, how many teeth are there on your cog set and how big are the cogs? If your cogs are the smaller type, you can get steel replacements:



The later SWX02 series and the G0 series use larger diameter nylon cogs which seem more durable.

You could also add ATF to your hub to improve cooling which might stop the cogs getting so hot.

 

[vfr400]

Those torque figures are pretty well meaningless. Motors are transducers. They simply convert electrical power into mechanical power. If they give a rated torque, that's how much torque they can run at continuously without destroying themselves.

With any electric particular motor, torque is proportional to current (within constraints, so how much torque you get from any motor depends on which controller you use and how much current it allows. Other factors that affect torque between motors are internal gearing, where they can trade external speed for torque, and the winding speed, which affects the efficiency.

In summary, if you take 260 rpm versions of the 30 Nm G310 and the much larger 60Nm BPM and use the same 36v 15 amp controller, the torque you get will be approximately the same.

To handle high currents for high torque, you need a motor with large robust windings, and to transmit the torque, it needs big strong gears, which is why I recommend the Bafang BPM/CST or equivalents from MXUS, Xofo or Xiongda. Xiongda would probably stamp or label your motor 250w and give you a certificate if you ask them nicely.

 

[vulcanears]

What might be nice is to try the G040250DC, it's torque is rated as 60Nm:

I've seen that one on the Bafang OEM website, but never found a website that actually sells the 250W G040 version. Asked 2 sellers on alibaba, but their response was rather confusing.


Regarding the nylon cogs: The G310 uses non-standard nylon gears that look like this:

 

[vfr400]

I've seen that one on the Bafang OEM website, but never found a website that actually sells the 250W G040 version. Asked 2 sellers on alibaba, but their response was rather confusing.


Regarding the nylon cogs: The G310 uses non-standard nylon gears that look like this:

Those 2-stage gears are the same as used on the Q-series motors (AKM). They're not as durable or strong as single-stage gears because of the smaller diameter, which means less tooth contact and fewer teeth to spread the wear over.

 

[vulcanears]

In summary, if you take 260 rpm versions of the 30 Nm G310 and the much larger 60Nm BPM and use the same 36v 15 amp controller, the torque you get will be approximately the same.

Thank you, your input was very helpful.
Is the gear reduction ratio of any importance here? (The G310 runs at 1:11)

To handle high currents for high torque, you need a motor with large robust windings, and to transmit the torque, it needs big strong gears, which is why I recommend the Bafang BPM/CST or equivalents from MXUS, Xofo or Xiongda. Xiongda would probably stamp or label your motor 250w and give you a certificate if you ask them nicely.

I've tried to find the Bafanc CST with a 250W label for quite a while now - with no success so far. If anyone has a source, I'd be all ears!

Could you let me know which 250W models from MXUS, Xofo or Xiongda are equivalent to the CST? There are so many different ones out there that I'm severely overwhelmed. Thank you in advance!

 

[vulcanears]

Those 2-stage gears are the same as used on the Q-series motors (AKM). They're not as durable or strong as single-stage gears because of the smaller diameter, which means less tooth contact and fewer teeth to spread the wear over.

I found that out after burning through several sets of them (and they are quite expensive and rather hard to find). The G310 is a really nice and quiet, but really not durable enough for my usage.

 

[WheezyRider]

Those torque figures are pretty well meaningless. Motors are transducers. They simply convert electrical power into mechanical power. If they give a rated torque, that's how much torque they can run at continuously without destroying themselves.

With any electric particular motor, torque is proportional to current (within constraints, so how much torque you get from any motor depends on which controller you use and how much current it allows. Other factors that affect torque between motors are internal gearing, where they can trade external speed for torque, and the winding speed, which affects the efficiency.

In summary, if you take 260 rpm versions of the 30 Nm G310 and the much larger 60Nm BPM and use the same 36v 15 amp controller, the torque you get will be approximately the same.

To handle high currents for high torque, you need a motor with large robust windings, and to transmit the torque, it needs big strong gears, which is why I recommend the Bafang BPM/CST or equivalents from MXUS, Xofo or Xiongda. Xiongda would probably stamp or label your motor 250w and give you a certificate if you ask them nicely.

As you say, the BPM/CST or equivalents would be good options, if you can find them.

Motor companies make a baffling range of products and often publish dubious data on outputs torque etc.

Two motors with the same controller and voltage can produce different torque values. This can depend for one thing on the gearing ratio, but also the configuration of the windings and the strength/configuration of the magnets. Even the spacing between the magnets and the coils can have a large effect. Also, controllers need tweaking for different motors to get the best out of them.

Torque is proportional to the flux *current*power factor. These can vary from one motor to the next for a fixed current.

 

[vfr400]

Thank you, your input was very helpful.
Is the gear reduction ratio of any importance here? (The G310 runs at 1:11)



I've tried to find the Bafanc CST with a 250W label for quite a while now - with no success so far. If anyone has a source, I'd be all ears!

Could you let me know which 250W models from MXUS, Xofo or Xiongda are equivalent to the CST? There are so many different ones out there that I'm severely overwhelmed. Thank you in advance!

High reduction ratios allow high power from a small motor. The faster the internal motor spins, the more power you get. You have to put the power in to get it out, so you don't get something for nothing. Consider the high speed R/C motors that I use in model aircraft. They're tiny, like 48mm long and 38mm diameter, and run with 55 amps continuous with a 4S battery, which is over 800 watts. They give more power than the average ebike motor.

The Xiongda and MXUS motors are exact clones of the Bafang BPM and CST, so you can compare pictures and dimensions. It's quite easy to recognise them.

CST clone:

Ytw-05 Electric Bicycle Bldc Hub Motor Cassette - Buy Electric Bicycle Motor Cassette,Electric Bike Motor Cassette,Hub Motor Cassette Product on Alibaba.com

Ytw-05 Electric Bicycle Bldc Hub Motor Cassette - Buy Electric Bicycle Motor Cassette,Electric Bike Motor Cassette,Hub Motor Cassette Product on Alibaba.com

www.xiongdamotor.com.cn

BPM clone

Wholesale Xiongda Ytw-05 Electric Brushless Dc Hub Motor For Bicycle/electric Bicycle Hub Motor - Buy Electric Motor For Bicycle,Brushless Hub Motor,Bicycle Hub Motor Product on Alibaba.com

Wholesale Xiongda Ytw-05 Electric Brushless Dc Hub Motor For Bicycle/electric Bicycle Hub Motor - Buy Electric Motor For Bicycle,Brushless Hub Motor,Bicycle Hub Motor Product on Alibaba.com

www.xiongdamotor.com.cn

Xiongda also offer flexible kits with built motor wheels, where you can specify your motor. The best way to deal with it would be to send an email to bonnie@xiongdamotor.com.cn. tell her what you want and ask her what she can do. Remember she's Chinese, so don't use jargon, euphemisms or complicated sentences.

The 48v kit with the SWX02 that Woosh do would also be pretty good for what you want if they get it in stock. It saves a lot of messing about. Maybe, they'll sell you just the motor wheel if that's all you want.

 

[WheezyRider]

I've seen that one on the Bafang OEM website, but never found a website that actually sells the 250W G040 version. Asked 2 sellers on alibaba, but their response was rather confusing.


Regarding the nylon cogs: The G310 uses non-standard nylon gears that look like this:

Ah, I see. The SWX02 and the RM G020250DC have simple straight cogs. They are probably a bit noisier, but more durable. I regularly run both of these motors at 800 to 900 W input at 59V and have never had a problem with the nylon cogs. When I took the G020250 apart, the clutch was even stamped with a 350W part number, so seems designed to take significantly more than 250W motor output.

The reduction ratio on the G020250 is 1:5 whereas the G310 is 1:11, yet the G310 is quoted to give less torque, which is interesting. I suppose the G310 core must be designed to spin faster?

I did find this website for the G040 version:

Buy Electric Bike Motor Bafang Rm G040.250.dc Rear 250w 36v Motor from Jinhua Queene Electric Technology Co., Ltd., China | Tradewheel.com

Buy low price Electric Bike Motor Bafang Rm G040.250.dc Rear 250w 36v Motor by Jinhua Queene Electric Technology Co., Ltd., a leading supplier from China. 188 similar products are also available from global exporters.

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Don't know if that's any better than Alibaba...

But maybe you'll find the BPM clones easier to get hold of.

 

[vfr400]

Ah, I see. The SWX02 and the RM G020250DC have simple straight cogs. They are probably a bit noisier, but more durable. I regularly run both of these motors at 800 to 900 W input at 59V and have never had a problem with the nylon cogs. When I took the G020250 apart, the clutch was even stamped with a 350W part number, so seems designed to take significantly more than 250W motor output.

The reduction ratio on the G020250 is 1:5 whereas the G310 is 1:11, yet the G310 is quoted to give less torque, which is interesting. I suppose the G310 core must be designed to spin faster?

I did find this website for the G040 version:

Buy Electric Bike Motor Bafang Rm G040.250.dc Rear 250w 36v Motor from Jinhua Queene Electric Technology Co., Ltd., China | Tradewheel.com

Buy low price Electric Bike Motor Bafang Rm G040.250.dc Rear 250w 36v Motor by Jinhua Queene Electric Technology Co., Ltd., a leading supplier from China. 188 similar products are also available from global exporters.

www.tradewheel.com

Don't know if that's any better than Alibaba...

But maybe you'll find the BPM clones easier to get hold of.

The torque quoted is the rated torque, not the ouput torque.

 

[WheezyRider]

High reduction ratios allow high power from a small motor. The faster the internal motor spins, the more power you get. You have to put the power in to get it out, so you don't get something for nothing. Consider the high speed R/C motors that I use in model aircraft. They're tiny, like 48mm long and 38mm diameter, and run with 55 amps continuous with a 4S battery, which is over 800 watts. They give more power than the average ebike motor.

The Xiongda and MXUS motors are exact clones of the Bafang BPM and CST, so you can compare pictures and dimensions. It's quite easy to recognise them.

CST clone:

Ytw-05 Electric Bicycle Bldc Hub Motor Cassette - Buy Electric Bicycle Motor Cassette,Electric Bike Motor Cassette,Hub Motor Cassette Product on Alibaba.com

Ytw-05 Electric Bicycle Bldc Hub Motor Cassette - Buy Electric Bicycle Motor Cassette,Electric Bike Motor Cassette,Hub Motor Cassette Product on Alibaba.com

www.xiongdamotor.com.cn

BPM clone

Wholesale Xiongda Ytw-05 Electric Brushless Dc Hub Motor For Bicycle/electric Bicycle Hub Motor - Buy Electric Motor For Bicycle,Brushless Hub Motor,Bicycle Hub Motor Product on Alibaba.com

Wholesale Xiongda Ytw-05 Electric Brushless Dc Hub Motor For Bicycle/electric Bicycle Hub Motor - Buy Electric Motor For Bicycle,Brushless Hub Motor,Bicycle Hub Motor Product on Alibaba.com

www.xiongdamotor.com.cn

Xiongda also offer flexible kits with built motor wheels, where you can specify your motor. The best way to deal with it would be to send an email to bonnie@xiongdamotor.com.cn. tell her what you want and ask her what she can do. Remember she's Chinese, so don't use jargon, euphemisms or complicated sentences.

The 48v kit with the SWX02 that Woosh do would also be pretty good for what you want if they get it in stock. It saves a lot of messing about. Maybe, they'll sell you just the motor wheel if that's all you want.

The BPM and CST clones have the same code - YTW_05, although in one link the motor is silver, in the other it is black. Out of curiosity vfr, what was the difference between the original BPM and the CST?

 

[vfr400]

The BPM and CST clones have the same code - YTW_05, although in one link the motor is silver, in the other it is black. Out of curiosity vfr, what was the difference between the original BPM and the CST?

The CST is the cassette (free-hub) version of the BPM.

When the BPM was developed, Bafang didn't make any cassette motors. the CST was the first, and it was a revelation at the time. These motors can easily cope with 25 amps at 48v.

I've built a few bikes with it. One was for a guy with only one leg, so he had to rely on the motor to take him everywhere without any pedal effort. He was quite heavy, and he had had his driving licence taken away because of his bad eyesight. After many years use, his health deteriorated so he couldn't use the bike anymore and he gave the bike back to me. My Nephew now has it as his only means of transport. He is also very over-weight and has mobility issues. The bike is now 6 years old.

There's no question that these motors aren't workhorses.

 

[vulcanears]

Does anyone know how the G040.250.DC compares to the Bafang CST?

Component

Bafang description

www.bafang-e.com

I've read something along "G040 (formerly CST)" several times on aliexpress.

 

[vfr400]

Does anyone know how the G040.250.DC compares to the Bafang CST?

Component

Bafang description

www.bafang-e.com

I've read something along "G040 (formerly CST)" several times on aliexpress.

It's the same motor, they just changed their designations. Bafang make two versions of each of the BPM and CST. One is 250w/350w and the other is 500w. The 500w one has thicker wire in the windings and can handle a lot more power. It's very hard to tell the difference from the outside or from a photo other than by the markings. Also there are many differences inside in all versions as they improved and modified things over the years, like changing from white to blue gears, from keyway clutch to splined, and bearing sizes changed.

 

[WheezyRider]

The CST is the cassette (free-hub) version of the BPM.

When the BPM was developed, Bafang didn't make any cassette motors. the CST was the first, and it was a revelation at the time. These motors can easily cope with 25 amps at 48v.

I've built a few bikes with it. One was for a guy with only one leg, so he had to rely on the motor to take him everywhere without any pedal effort. He was quite heavy, and he had had his driving licence taken away because of his bad eyesight. After many years use, his health deteriorated so he couldn't use the bike anymore and he gave the bike back to me. My Nephew now has it as his only means of transport. He is also very over-weight and has mobility issues. The bike is now 6 years old.

There's no question that these motors aren't workhorses.

Ahh, I see now, obvious when you know what you are looking for

 

[WheezyRider]

The CST is the cassette (free-hub) version of the BPM.

When the BPM was developed, Bafang didn't make any cassette motors. the CST was the first, and it was a revelation at the time. These motors can easily cope with 25 amps at 48v.

I've built a few bikes with it. One was for a guy with only one leg, so he had to rely on the motor to take him everywhere without any pedal effort. He was quite heavy, and he had had his driving licence taken away because of his bad eyesight. After many years use, his health deteriorated so he couldn't use the bike anymore and he gave the bike back to me. My Nephew now has it as his only means of transport. He is also very over-weight and has mobility issues. The bike is now 6 years old.

There's no question that these motors aren't workhorses.

vfr, have you built any Xiongda CST clone based e-bikes?