Suggest hub motors for our cargo trike!

[wilca428]

We need two new hub motors for our cargo trike (bakfiets.nl, two front wheels). Our present ones are Tongxin (250w 120swx 24v 175rpm) with rollers as planetaries get broken all the time. Battery is 24v. 100 mm dropouts and need to fit im80 roller brakes. The controller is a black box, but can be substituted if necessary.

Please, can you help us!

Kind regards.

Wilhelm

 

[SlowCo]

As you're illegal already (2x 250W) wouldn't a low kV direct drive rear hub (no internal gears) or a Bafang BBS01/02 be a better solution?
http://mtb-ombouw.nl/producten?field_category_name=Bafang middenmotor BBS01/BBS02

 

[Drunkskunk]

+1
You're already running an illegal bike. Why keep fitting inferior equipment? A BBS02 makes more sense.
Refitting the bike to get away from roller brakes also makes a lot of sense.

 

[dogman dan]

If you are going to be beyond 250w, go for a wattage that will really help a heavily loaded cargo bike.

Bigger motors, like a Mac 500w geared, with disc mounts. Fairly easy to make your own, and weld a disc brake mount to a steel fork.

Then if you run those motors at 1000w each, 48v 20 amps controllers, you have 2000w of power when you need it, and dual disc brakes. Or run a mellow 36v, only 1500w and about 20 mph top speed.

Not a cheap upgrade, but well worth it. EM3ev, get the slow rpm motor, 12t if he still stocks them. 10t if not.

A mid drive like the BBS02 can also be a good choice, getting more out of 750w by gearing down real low. I'd still want to convert those brakes to disc though.

 

[d8veh]

If you're happy with the power of your Tongxin, but not the reliability, any front Chinese 24v 250w hub motor would be OK. You have to look on Aliexpress for roller-brake ones. Are your forks steel so that they can be opened up a bit because the roller brake motors are a bit wider, I believe? What size wheel?

 

[wilca428]

Thank you all soooo much for your help!

If you're happy with the power of your Tongxin, but not the reliability, any front Chinese 24v 250w hub motor would be OK. You have to look on Aliexpress for roller-brake ones. Are your forks steel so that they can be opened up a bit because the roller brake motors are a bit wider, I believe? What size wheel?

Yes! You nailed it - we want reliability, not more power. It takes all the foodstuff or kids we load on it anywhere without strain. It feels balanced to the rest of the bike (brakes, geometry, wooden box etc). Are all front Chinese 24v 250w ok, or should we aim for any particular brand? We are very interested in reliability.

The forks are steel, 100 mm, but they are hard to widen because they are so short. Wheels are 20".

We want to be able to use foot brake on this bike. I know it is weak and all, but we need it because many people believe they need it. Does that excluse all middrives?

 

[motomech]

The Q series of motors are reliable, and they are on sale;
https://bmsbattery.com/ebike-kit/437-q85-36v250w-roller-brake-front-driving-hub-motor-ebike-kit.html
I'm assuming you would want the high speed(328)motors.
That would be a top speed of 21 Kph on a 24V battery.

 

[dogman dan]

Silly me, I thought flogging the motors so hard with that much weight was the reason for unreliability.

What exactly gets broken all the time on them?

Converting to dual disc brakes still makes sense, if your new motors have a disc mount. Not hard at all for a good welder to make and add the mounts to your steel forks.

 

[dnmun]

me too. especially if the gears wore out. but reliability is a general term and could mean anything. bad wiring, loose nuts, loose spokes, could be anything imo. never defined here.

 

[amberwolf]

Given Tongxin's design, I would bet that what breaks is the ring around the rollers or clutch; it's got two pin holes in it which make make for a serious weak point, and it seems to cause fracture there, so the power no longer gets from motor to wheel.

Keyde roller motors do the same thing, AFAICR.

 

[wilca428]

Converting to dual disc brakes still makes sense, if your new motors have a disc mount. Not hard at all for a good welder to make and add the mounts to your steel forks.

So disc brakes is better than roller brakes everyday? Even in the cold salted swedish winter?

Given Tongxin's design, I would bet that what breaks is the ring around the rollers or clutch; it's got two pin holes in it which make make for a serious weak point, and it seems to cause fracture there, so the power no longer gets from motor to wheel.

Yes. It is always the ring around the rollers, but actually not at the pin holes you mention. To weak for its own power. I've read many of the reports on Tongxin failiures.

 

[wilca428]

Do you think it is possible to hook up two of for example those Q85s to our current controller? Or do we need a new one? And does any controller work with double motors?

 

[dogman dan]

Disc would surely be better than brakes that fail, and you have to fix the motor to repair.

Disc will work in wet, but it's true, salt will eat away at them over time. But replacing an entire disc caliper can be very cheap, and I doubt the problem would be so bad it had to be done every year.

 

[d8veh]

Do you think it is possible to hook up two of for example those Q85s to our current controller? Or do we need a new one? And does any controller work with double motors?

Q-series motors don't run very well sensorless.

 

[wilca428]

Ok...

It seems that Q85 is 36V only if possible to fit with rollerbrakes.

Anyone who knows quality hubmotors 24V 250-500W adapted for rollerbrakes?