Hub motor recommendations for a cargo bike in a hilly town

[neptronix]

Ah, 20" wheel isn't hurting for torque.. just know that there's a lot more torque potential in that motor.

TBH if you have this small wheel size you're in a perfect place for a hub, and a mid drive stops making sense. The added regenerative braking really matters on a heavy bike. And if you are on mostly flat land, the hub motor wins the efficiency contest because of the regenerative ability.

 

[Bullfrog]

Hello.

I'm from a hilly town in Quebec. Winters are cold and snowy, and I bike all year round.

I just got a longtail cargo bike with a 20" rear wheel, the Edgerunner and I'd like to convert it to an ebike.

I presently have a BBS02 on a mountain bike that can haul the kids and groceries uphill which is great! For this bike though, I've been strongly recommended to go with a hub motor to preserve the drive train. I also personally like the ruggedness of hub motors and the fact that they require less maintenance. I'd also really enjoy torque sensing this time around.

I'm looking at a rear motor build because I think a front motor in icy weather will be too much for my girlfriend to handle.

I have my eyes on the new Grin All Axle v3 with integrated torque sensing. They recommend the Fast winding for 20" wheels, but if I compare it to a fatbike I just sold that had a G60 rear hub at 500w with 26" wheels that I found lacked torque when climbing the Grin motor is even worse taking wheel difference in consideration. Here's the simulation.

Here are my questions:
- Will this motor suffice?
- Should I change the winding to have more torque?
- Do you have any other motor recommendations.
- Should I opt for a geared motor? A friend has a GMAC and just had a pretty hefty maintenance bill because gunk was getting in and cogs needed changing...
- Should I just go for a mid drive?

Thank you!!!!

First of all, changing the winding will NOT give you more torque! The torque per battery amp is set for a given motor design no matter what winding you use.

Secondly, you are comparing apples and oranges when you compare the Bafang G60 which is a geared hub motor to a Direct Drive hub motor like the Grin All Axle v3.

I would go with a Bafang BBSHD (the BBS02 is also a good choice) because the aftermarket support is superior to the 01 and 02 motors so finding a controller that can give you the torque you want will be much easier.

The other option is a big Direct Drive motor...big in that it at least has a 205mmx35mm stator and bigger/wider would be better.

I am a huge MAC fan but I am afraid it might over heat if used for a cargo bike. Although the 20" rim would help and you CAN lace a MAC/GMAC in a 20" wheel and use a one cross pattern since it is smaller in diameter than a Direct Drive motor with a 205mm stator...AND the MAC/GMAC produces more torque per battery amp than any motor currently in the drop down menu of the Grin Tech Motor Simulator. The MAC is not capable of regen but the GMAC is.

If you limit the amperage to the motor enough, any motor will work without over heating but the lower the amperage the lower the torque output.

To keep your bike from getting real heavy, I'd go with your BBS02 if you can get a controller that will produce enough torque for your needs or the BBSHD since I know Luna sells a good controller for it.

I would not go with a Direct Drive Hub Motor because with a 20" wheel you'll need to use a Radial lacing pattern for most Direct Drive motors that are big enough to have decent power i.e. 205mm stator and roughly 225mm circle for the spokes...that only leaves about 90mm between the motor and the rim so it is going to be challenging if not impossible to lace a one cross pattern in a 20" rim. Regen braking would be nice to have but would require a one cross lacing since the Radial pattern would not hold up too good with torque in both directions due to regen.

 

[nicobie]

Ah, 20" wheel isn't hurting for torque.. just know that there's a lot more torque potential in that motor.

TBH if you have this small wheel size you're in a perfect place for a hub, and a mid drive stops making sense. The added regenerative braking really matters on a heavy bike. And if you are on mostly flat land, the hub motor wins the efficiency contest because of the regenerative ability.

Maybe it's just me, but I don't think that a mid drive setup ever makes sense. To much stuff to break and limited to light usage

 

[Popstar]

I've been running 52V 20ah BBSHD on a Madsen longtail bucket bike with 2+ kids for 6 years, and I can say that the BBSHD is both the Least Powerful AND the Most Powerful motor that is good for carrying 2 kids in hilly area. Any less power and the 0-3 mph dead zone is in danger of tipping over, while top speed of 30mph is def too scary for the stiffness and brakes of a converted bike to cope.

 

[gromike]

If I were carrying kids on a cargo bike I would really want to have a direct-drive hubmotor somewhere on the bike (or trike).

 

[neptronix]

If you were to:
- add an extremely strong ( talking downhill bike fork here, don't spend less than $400 ) suspension fork then change that front wheel to a size down
- put as large of a tire as possible in the rear

The riding qualities of said bike would improve massively, especially since you're almost sitting on the front fork, weight balance wise.

 

[smitty2k1]

First of all, changing the winding will NOT give you more torque! The torque per battery amp is set for a given motor design no matter what winding you use.

Secondly, you are comparing apples and oranges when you compare the Bafang G60 which is a geared hub motor to a Direct Drive hub motor like the Grin All Axle v3.

I would go with a Bafang BBSHD (the BBS02 is also a good choice) because the aftermarket support is superior to the 01 and 02 motors so finding a controller that can give you the torque you want will be much easier.

The other option is a big Direct Drive motor...big in that it at least has a 205mmx35mm stator and bigger/wider would be better.

I am a huge MAC fan but I am afraid it might over heat if used for a cargo bike. Although the 20" rim would help and you CAN lace a MAC/GMAC in a 20" wheel and use a one cross pattern since it is smaller in diameter than a Direct Drive motor with a 205mm stator...AND the MAC/GMAC produces more torque per battery amp than any motor currently in the drop down menu of the Grin Tech Motor Simulator. The MAC is not capable of regen but the GMAC is.

If you limit the amperage to the motor enough, any motor will work without over heating but the lower the amperage the lower the torque output.

To keep your bike from getting real heavy, I'd go with your BBS02 if you can get a controller that will produce enough torque for your needs or the BBSHD since I know Luna sells a good controller for it.

I would not go with a Direct Drive Hub Motor because with a 20" wheel you'll need to use a Radial lacing pattern for most Direct Drive motors that are big enough to have decent power i.e. 205mm stator and roughly 225mm circle for the spokes...that only leaves about 90mm between the motor and the rim so it is going to be challenging if not impossible to lace a one cross pattern in a 20" rim. Regen braking would be nice to have but would require a one cross lacing since the Radial pattern would not hold up too good with torque in both directions due to regen.

RE: lacing pattern. Grin specifically suggests radial lacing for their all Axle hub motor with regen. All-Axle Hub Motor - Grin Products - Product Info

RE: power. I've now got 50 miles or so on my Grin All Axle V3 powered by a 52v 20ah battery and baserunner controller. So far it has been enough power in my 20" rear wheel on my longtail cargo bike carrying one kid. I've only been using it in assist level 1/9! I do have a couple quirks im trying to work out. The motor cut out a few times in a big hill when I was trying to put down as much power as I could in a high assist level. According to Grin this "is the result of electrical noise from the motor interfering with the communications on these displays which is just a 0-5V single ended UART and not very noise immune. You'll see the "ERR30" message show up briefly and then it will clear itself once the noise levels are low enough. We're actively trying to see if there are any ways of reducing the display's susceptibility in this through external chokes or similar, but you can be assured that the throttle works fine in the meantime (since it doesn't involve any display communications)."

Seems it wouldn't have been a problem if I went with the cycle analyst instead of superharness. Hasn't been an issue since but I haven't tried to replicate it.

Plenty of power with throttle too, but I don't use it much.

 

[Bullfrog]

RE: lacing pattern. Grin specifically suggests radial lacing for their all Axle hub motor with regen. All-Axle Hub Motor - Grin Products - Product Info

RE: power. I've now got 50 miles or so on my Grin All Axle V3 powered by a 52v 20ah battery and baserunner controller. So far it has been enough power in my 20" rear wheel on my longtail cargo bike carrying one kid. I've only been using it in assist level 1/9! I do have a couple quirks im trying to work out. The motor cut out a few times in a big hill when I was trying to put down as much power as I could in a high assist level. According to Grin this "is the result of electrical noise from the motor interfering with the communications on these displays which is just a 0-5V single ended UART and not very noise immune. You'll see the "ERR30" message show up briefly and then it will clear itself once the noise levels are low enough. We're actively trying to see if there are any ways of reducing the display's susceptibility in this through external chokes or similar, but you can be assured that the throttle works fine in the meantime (since it doesn't involve any display communications)."

Seems it wouldn't have been a problem if I went with the cycle analyst instead of superharness. Hasn't been an issue since but I haven't tried to replicate it.

Plenty of power with throttle too, but I don't use it much.

They don't recommend a Radial lacing pattern, they said "The spoke holes are paired sufficiently close that there is NO NEED to have the spokes cross over. With a radial lacing the spokes have an effective angle that is the same as a regular hub with a triple cross."

In the unique case of the 32 spoke hole Grin All Axle V3 motor, I agree there is no need to use a cross pattern because the spoke angles are sufficient to handle the torque in both directions. The spoke angle in both directions is what you are after and Justin/Grin did a very good job with the design. A true Radial pattern would have an angle of 90 degrees between the spokes and the rim and in the case of the All Axle V3 motor, you end up with 85 degrees according to Grin.

Thanks for the link and pointing out a "Radial" lacing pattern will work with the Grin All Axle V3 motor .