Front hub 48v motor for very hilly area

[BidelloZ]

Hi all,
Been doing some extensive reading on these pages, let me start thanking everybody for all the great info.

I’m currently faced with this task: I’ve got a cargo bike (two wheels, 20’’ front) which I’m planning to fit with an electric motor.

Of course plenty of options, but for many reasons, one being not having yet decided whether to keep the current setup (42t chainring, 10 speed cassette) over a rear hub, possibly even a belt driven one, I would like to have a front hub for the moment.

Also (and don’t know whether this is possible) I would like to avoid a cadence sensor on the BB for the above reasons. Basically I’d want a setup all confined to the front wheel.

Between the Xionda, BPM, MXSUS hubs etc, I’ve seen there is much to choose from.

I should say that I have already a nice 48v 13.8Ah battery which I’d like to use.

So ideally a 48v front (geared I guess) 250w hub would be perfect.

Here’s my question: can I just get an 48v hub motor, suitable controller, display and thumb throttle, and install it to basically only work on throttle and not cadence?
I’d be using it only to take off the edge when pedalling uphill with two kids in the front box.

Many thanks for your thoughts.

 

[Nealh]

WIth your kids on board you will want to be legal, fit cadence sensor with hub and a throttle for pedal first operation. Cadence sensor gives more options and allows better rider control, or go the torque sensor mid drive route with TDZS2.

 

[BidelloZ]

Thanks for replying Nealth, appreciate it.

Yeah I need it to be legal.

Bike was second hand, came with a BBSHD which pulled like a truck, but was totally illegal of course.

Mid drives are still good options but I’d stick with a front hub so that I can build my rear drive the way I like.
Besides, many cargo users of my same model reported front hubs being very good given the whell is only 20’’ and most of the load being there.

I guess I could still somehow fit a cadence sensor and mod things accordingly to whichever setup I choose in the future.

But won’t any hub work just on thumb throttle?

One more thing: I like the SWX02 hub, what is the corresponding model for the front wheel? And, can it be run at 48v with the right controller?
Or am I better off with an MXUS 48v?

Read that the xiongda dual speed doesn’t freewheel as nice, and I need a hub with low drag as the bike will be just pedal propelled on the flats.

 

[anotherkiwi]

I agree with Nealh. Show us a picture of your bottom bracket left hand side so that we can see if there is enough space for a PAS disk like this one which requires no disassembly of the crank etc.

 

[anotherkiwi]

One more thing: I like the SWX02 hub, what is the corresponding model for the front wheel? And, can it be run at 48v with the right controller?
Or am I better off with an MXUS 48v?

Try here, specs are down the page.

https://fr.aliexpress.com/item/32835021876.html

The SWX02 can handle very large voltages and is a hot rod favorite. A 36v one run at 48v will not be an issue.

 

[BidelloZ]

BB a standard 68mm one, only got this pic on my mobile now (took it to show a friend the grinding done by the BBSHD I removed).
A cadence sensor will be easy enough to fit right now (have a standard shimano setup at the moment) but I’m really leaning towards a belt drive and rear hub (dreaming of a rohloff but can’t afford that).

Thanks for the link above. Yep had seen those motors on Aliexpress.

So SWX02 better than an MXSUS XF07?

Would you guys mind looking at my shopping list, after I come up with one that is?
Cheers

 

[Audio2]

Its 350 watt so not legal in Uk.

 

[BidelloZ]

Its 350 watt so not legal in Uk.

The XF07 is 350w?

Am I reading the wrong specs then?

From Aliexpress:

PRODUCT DETAILS

Model: MXUS XF07

Rated Voltage(V):24V36V/48V

Rated Power(W):250W

Wheelsize(inch):16-28inch

Rated Speed(km/h):25-28km/h

Reduction Ratio:1:4.4

Weight(KG):3

Spoke: 36 hole spoke 12G/13G

Position: Front

 

[BidelloZ]

BB a standard 68mm one, only got this pic on my mobile now (took it to show a friend the grinding done by the BBSHD I removed).

Sorry realised I forgot to upload the pic

 

[Audio2]

No SWX02 is 350 watt.

 

[Woosh]

No SWX02 is 350 watt.

these 'watts' are just guideline, minimum guarantee that the motor won't overheat when you use them up to the rated power shown on the factory label.
Unfortunately, the police are not necessarily experts on e-bike motors. If they see '350W' label, they may assume that you ride an illegal bike.
You can look up how many Watts that the motor actually produces on the ebikes.ca website.
For example, if you run the XF07 on your 48V battery, you will get this (no pedalling):

https://www.ebikes.ca/tools/simulator.html?axis=mph&motor=MXUS_XF07&batt=B4814_EZ&hp=0

Look closely at the black load plot. At 15mph and zero gradient, the motor produces 180 Watts, hardly illegal if you do not derestrict the bike.
At 20mph, the motor produces 350W. So, legality aside, if you want to ride at 20mph, a 350W XF07 is a good choice because it weighs only 3kg and is a lot cheaper than the Bafang SWX02.

As for the SWX02, use this link for a simulation:
https://www.ebikes.ca/tools/simulator.html?axis=mph&motor=MBPM&batt=B4814_EZ&hp=0

 

[BidelloZ]

Thanks, that’s what I thought, that the SWX02 in many kits it’s legal when run within the legal road limits. If one derestricts it and “hot rods” it, surely it will be illegal. But that’s true for many other motors I guess.

I’m liking the SWX02 because of the higher rated torque, which should be quite nice on my 20’’front wheel

 

[Woosh]

I’m liking the SWX02 because of the higher rated torque, which should be quite nice on my 20’’front wheel

not good on the front wheel.
The torque on 20" wheel is typically 30% higher than on a 26"-29" wheels at the same speed.
If you put higher torque on the wheel, you need higher adherence to the road surface otherwise the motor will cause the bike to skid.
I always check the rider's weight on my Big Bears that have front wheel motor. If they are less than 15-16st, I would suggest another bike with crank drive or rear motor.

This is an XF07 on 20" rim:

http://wooshbikes.co.uk/2019/foldingbike/tskit-13ah.jpg

If you want stable, good torque on 20" wheel, fit a 48V TSDZ2 to your bike.
http://wooshbikes.co.uk/cart/#/product/uid-205-tsdz2/tsdz2-cd-kit-48v-15a-250w

 

[BidelloZ]

Hi Woosh (Tony?)
We exchanged quite a few emails I believe...
Mine is a cargo bike, with a front box where I load two children. For this very reason you recommended an SWX02 and maintained the TSDZ2 would just melt under load ;-)

I was going to follow your suggestion and get an SWX02 for the rear wheel, but decided against messing with the rear as I haven’t decided whether to keep the current 10 speed cassette and derailleur or get an Alfine (or better) with belt.

Besides, I very much doubt a small 250w hub, even derestricted would make the front 20’’ wheel slip when I have the kids in the front box

Pic of the bike attached

 

[Woosh]

OK, I remember you now.
Front motor it is then.

 

[vfr400]

For a bike like that, you need a robust motor like a Bafang BPM. You can find them stamped 250W, but you have to hunt around now.

 

[BidelloZ]

For a bike like that, you need a robust motor like a Bafang BPM. You can find them stamped 250W, but you have to hunt around now.

Roger that.

So far we have:

- SWX02
- XF07
- BPM

I understand these are very good choices.
Not interested in speed, uphill I usually plough ahead at 8-9 mph, but with the front load it’s really hard work. So a robust hub that takes the edge off is all I need, not looking to increase said speed.

Since a 250w stamped BPM seems hard to find, should I focus on the other two? Also the XF07 seems much cheaper. But that isn’t a deal breaker, I want something sturdy that won’t burn under the load.

Cheers

 

[vfr400]

It's more the weight than anything. the plastic gears inside the BPM are much bigger and stronger than the other motors. It's a motor designed for high torque. The XF07 can't hold a light to it. The SWX02 is half-way between the two, but many of them are around 270RPM. For a 26" wheel, you'd need a slow wind motor of around 201 RPM or lower. That's a code 13 or higher. I think code 15 would be ideal. The code number is often marked on it in brackets. For a 20" wheel, 270 RPM would be OK. If you run at 48V in a 20" wheel, then you're back to the code 15 because it will run 33% faster at 48v.

 

[BidelloZ]

It's more the weight than anything. the plastic gears inside the BPM are much bigger and stronger than the other motors. It's a motor designed for high torque. The XF07 can't hold a light to it. The SWX02 is half-way between the two, but many of them are around 270RPM. For a 26" wheel, you'd need a slow wind motor of around 201 RPM or lower. That's a code 13 or higher. I think code 15 would be ideal. The code number is often marked on it in brackets. For a 20" wheel, 270 RPM would be OK. If you run at 48V in a 20" wheel, then you're back to the code 15 because it will run 33% faster at 48v.

Thanks very much for the detailed info.
Let’s leave the XF07 out then.

Will get on with the hunting and report back

 

[anotherkiwi]

Last night did a road test with the Mxus XF08 in it's new home, 936 Watts peak @ 24 Amps x 38v...

Top speed? 31 kmh. Top speed climbing? Too scared to look down, too busy holding onto the bars...