Biggest/most powerful 20" front wheel motor for cargo bike?

[scbk]

Hi again everyone.

Just got a Bakfiets long cargo bike that I'm going to convert to electric.
The rear wheel has hub gears, so don't want the hassle changing that.
Mid drive would put a lot of strain on the gears, it's a heavy bike, and will be carrying a load.


The front wheel is 20" (with disc brakes), what is the biggest front hub motor kit available in 20"?

When I say "biggest", I don't mean world record breaking! More like what is easy to buy that would be a step up from a yosepower 36v 250w.

Thanks

 

[Nealh]

I would disagree with you and say middrive , I fitted a tsdz2 to my Kona Ute and tow a trailer at times with 90 -100kg load . That said my small 1.6kg 250w G370 bafang front hub also manages the same load though my terrian use though is mainly offroad and is pretty flat bar one main road incline.

 

[saneagle]

Hi again everyone.

Just got a Bakfiets long cargo bike that I'm going to convert to electric.
The rear wheel has hub gears, so don't want the hassle changing that.
Mid drive would put a lot of strain on the gears, it's a heavy bike, and will be carrying a load.


The front wheel is 20" (with disc brakes), what is the biggest front hub motor kit available in 20"?

When I say "biggest", I don't mean world record breaking! More like what is easy to buy that would be a step up from a yosepower 36v 250w.

Thanks

Hub-motors work well in a 20" wheel for pulling high loads. What you want is any standard 250w one for a 26" wheel that should have a speed around 260 rpm. Run it at 48v to get the 328 rpm you need for 15 mph, and it'll have really good torque at say 15 amps.

If you want the best, a 328 rpm 48v Q128H motor from BMSBattery with a 22 amp controller will blitz it. You can't go much more powerful than that because you won't get enpough traction.

Q128 48V500W Front Driving V-Brake E-Bike Motor Wheel RPM 328

Q128 48V400W-500W Front Driving V-Brake E-Bike Motor Wheel. Hall sensor waterproof connector. You can select S09P, S12P or S12S controller for this motor.

bmsbattery.com

 

[Woosh]

Bafang BPM kit.

 

[scbk]

Looking on aliexpress/ebay a name that often comes up is CSC, don't know if they're any good or not. In 20" front wheel they advertise 36v 500w and 48v 1000w, shipped out from france in a fortnight

Electric Bicycle Conversion Kit, Front or Rear Wheel Hub Motor, 36V, 250W, 48V, 1500W, 20, 26, 27.5, 28, 29 Inch, 700C, SW900 - AliExpress 18

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

 

[Woosh]

if you buy directly from China, assume that you won't get any support, thus you should stick to saneagle's recommendation. The bmsbattery's Q128 motor has a high reduction ratio making it better suited for cargo bikes.
The kits you link to on Aliexpress are without specific brand and model, you can only guess if they will do what you need it to do. I recommend the BPM because I sell it.

 

[Bonzo Banana]

I would disagree with you and say middrive , I fitted a tsdz2 to my Kona Ute and tow a trailer at times with 90 -100kg load . That said my small 1.6kg 250w G370 bafang front hub also manages the same load though my terrian use though is mainly offroad and is pretty flat bar one main road incline.

Mid drive may handle the load no problem and even do a better job of it but the bike has hub gears so unless a basic 3 speed hub it could be very vulnerable to accelerated wear and damage with a mid-drive motor. The beauty of a front hub motor and rear hub gears is not only is it less likely to damage the hub gears compared to a mid-drive motor its even less likely to damage them compared to a standard bike. As you go up a hill now the hub motor takes a lot of load of the hub gears extending their life. As hub gears can be expensive to repair or replace this has to be the best option for a ebike that is going to get a lot of use and with higher loads.

 

[scbk]

Hub-motors work well in a 20" wheel for pulling high loads. What you want is any standard 250w one for a 26" wheel that should have a speed around 260 rpm. Run it at 48v to get the 328 rpm you need for 15 mph, and it'll have really good torque at say 15 amps.

If you want the best, a 328 rpm 48v Q128H motor from BMSBattery with a 22 amp controller will blitz it. You can't go much more powerful than that because you won't get enpough traction.

Q128 48V500W Front Driving V-Brake E-Bike Motor Wheel RPM 328

Q128 48V400W-500W Front Driving V-Brake E-Bike Motor Wheel. Hall sensor waterproof connector. You can select S09P, S12P or S12S controller for this motor.

bmsbattery.com

Cheers, looking at the Q128 on bms battery, it's listed as V brake only, the bike has discs front and back (which was an optional extra over roller brakes!)

 

[scbk]

Scrub that, seen they have it listed as 36v with v brake / disc brake

Q128 36V400W-500W Front Driving V-Brake E-Bike Kit RPM 328

Q128 36V400W-500W Front Driving V-Brake E-Bike Kit. Hall sensor waterproof connector.

bmsbattery.com

 

[saneagle]

Scrub that, seen they have it listed as 36v with v brake / disc brake

Q128 36V400W-500W Front Driving V-Brake E-Bike Kit RPM 328

Q128 36V400W-500W Front Driving V-Brake E-Bike Kit. Hall sensor waterproof connector.

bmsbattery.com

If you get the 36v one, go for the 260 rpm version and run it at 48v to get the speed and power.

 

[scbk]

Thanks,
Apart from the choice of rpm, are the 36v and 48v the same motor?


I did email bms battery to ask about the disc brake, maybe it's a mistake on the website?
Have you used the firm, what are they like to deal with and what is the normal delivery time?




I've had some items on aliexpress come from china in 2 weeks, others more like 2 months

 

[saneagle]

Thanks,
Apart from the choice of rpm, are the 36v and 48v the same motor?


I did email bms battery to ask about the disc brake, maybe it's a mistake on the website?
Have you used the firm, what are they like to deal with and what is the normal delivery time?




I've had some items on aliexpress come from china in 2 weeks, others more like 2 months

The 36v 260 rpm motor is the same as the 48v 328 rpm one apart from the markings.

BMS battery are pretty good. I've been using them since 2011. they're a typical Chinese supplier - can't speak much English and are OK as long as there are no problems.
There's also Topbikekit, Greenbikekit and possibly PSWPower that sell the same motor under different designations. Just look for the number 128 in the designation. Remember the speed is important: 36v 260 rpm run at 48v or 48v 328 rpm run at 48v.

 

[scbk]

Thanks, the choice is 201rpm or 328rpm, so go for the 201rpm then?



For controller should I get S-KU93?

S-KU93 36v/48v 500W 22A Controller

S-KU93 Controller. It is suitable for all our 250W, 500W motor and Q128 Motor. This controller is compatible with 48V and 36V battery.

bmsbattery.com

And display S-LCD8?

S-LCD8 LCD Meter for S-Series Controllers Color Black

S-LCD8 LCD Meter for S-Series Controllers

bmsbattery.com

I assume they work together?

 

[saneagle]

201 rpm at 48v will give you about 13 mph top speed on the road going up to about 15 mph with a fully-charged battery. You could run the 328 rpm one at 36v, but if you want high power, you'd need a bigger controller, say 25A. The S12S is quite big and you can set the current below 30A in the settings. Obviously, you need a decent battery for the higher current.

With the controller, you need an LCD, throttle, PAS (not 12 magnets) and probably best to get a speed sensor just in case you need one.

Often, after ordering, you get a request for more money for shipping. It's not a scam. It's just the way their shipping cost calculator doesn't work. It won't be a lot, and overall price is still fair.

Lot's of choices to juggle. It's always the same. You can never get quite what you want.

 

[scbk]

What would the top road speed be like if I bought the 36v 201rpm, and ran it at 48v?
20" wheel

 

[Woosh]

a 36V 201RPM motor will become 48V 201*1.3=261RPM
The maximum speed depends on the circumference of your tyre.
for example, your tyre is 20 x 1.95. Circumference: 1.57M
Maximum speed 261 * 1.57 * 60 = 24.6kph = 15.3mph
I would not recommend the Q128 for cargo bikes though. Its gearbox is too fragile in my view.
The Q128 has 140mm diameter like Bafang SWX02 but has higher gear reduction ratio.
I bought a sample Q128 with KT 20A 48V controller from bmsbattery years ago. I run it at 800W climbing a steep hill, it started whining after 5 minutes.

 

[saneagle]

a 36V 201RPM motor will become 48V 201*1.3=261RPM
The maximum speed depends on the circumference of your tyre.
for example, your tyre is 20 x 1.95. Circumference: 1.57M
Maximum speed 261 * 1.57 * 60 = 24.6kph = 15.3mph
I would not recommend the Q128 for cargo bikes though. Its gearbox is too fragile in my view.
The Q128 has 140mm diameter like Bafang SWX02 but has higher gear reduction ratio.
I bought a sample Q128 with KT 20A 48V controller from bmsbattery years ago. I run it at 800W climbing a steep hill, it started whining after 5 minutes.

The gears will be fine. it's a 20" wheel.

 

[scbk]

The next question is going to be which large 48v battery pack

The controller I've ordered is 30a max current.



I've already got one of these 48v 20ah batteries on another bike:

Varstrom 48V 18.0/20.0Ah Hailong G80 Max Down Tube Battery with Charger | Varstrom

Varstrom offers special batteries for Bafang motors, the battery has built-in BMS for Bafang motors, if you want to change a new bettery for your Bafang drive kit, Varstrom will bee the right choice for you.

varstrom.com

"Max Constant Discharge Current: 30 (A)
Peak Current: 60 (A)"


Or pswpower are advertising 48v 25ah for a smidgen less:

Electric bicycle ebike Battery 48V 25AH 35A Lithium eBike Battery fits 1500W motor the interior battery is SAMSUNGLi-ion battery

Electric bicycle ebike Battery 48V 25AH 35A Lithium eBike Battery fits 1500W motor the interior battery is SAMSUNGLi-ion battery

www.pswpower.com

"6. Continuous discharge current: 35A
7. Pulse/Max discharge current 70A"


any thoughts?

 

[saneagle]

You won't be able to use 30 amps at 48v with a front motor, even less so with a 20" wheel. The wheel will just spin. I'd say that 20 amps is about the maximum. You can get that by setting the controller to current control and not using level 5, or most versions have a way of reducing the current in the LCD settings.

Either way, your battery will be OK.

 

[scbk]

Cheers for the help from this forum, not just this thread but searching back through the archive of old threads.

She's up and running but not quite finished yet. No brake sensors yet, but they will be soon. Once they're on I will do a lap round the bike and tidy up the wiring and cable ties.
Not calibrated the speed yet.

The battery is under the bench seat, mounted on a little podium of 18mm ply just incase any water gets in (there is drain holes anyway)
Controller is screwed on to the underneath of the bench. There's a right rats nest of wiring in there that will have to be tidied up.
Cut 2 holes in the plywood box, one for wires, the other is to access the battery key lock.

Removed the 6v dynamo lights and replaced with 48v front and rear.

The motor is great, she pulls like a train.


Good fun bike