Hub motor recommendations for a cargo bike in a hilly town

L

laurentm

100 µW
Joined
Apr 25, 2024
Messages
9
Location
Quebec
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!!!!
 
A 20" wheel is where the all axle makes peak power and efficiency.

In your simulation you're running a baserunner which is providing nowhere near the amps required for that situation. The battery is sagging a ton also.

Motor Simulator - Tools

I suggest this scenario instead. You will get a sizeable increase in torque and efficiency.
If you have >4% grades then i would consider switching this motor for the RH212 fast winding and accepting the small extra weight.

This particular motor configuration maxes out the phaserunner's capabilities. The phaserunner taps out at 90A phase current but the motor could take 125A from a stop and burn rubber... :)
 
Woa, do I really need all that power? I'm no where near a 100% throttle no pedaling kind of guy.
I find it crazy that I need so much more power than with my BBS02. I expected it to be more power hungry without the gearing through the drivetrain, but didn't think it would be so much. I don't really need to climb that fast either. If I want to maintaint my battery and the baserunner, should I just switch to a mid drive or a geared motor?
 
Probably not, i'm just showing what's possible. You can tune the power down. You can pick a 48V or 36V battery instead of 52v if you want less speed.

BBS02 will have way lower power capability, lower efficiency, eat chains, cost more. You have the perfect wheel size to maximize the power/weight ratio of a small to mid sized hub.

I wouldn't recommend a baserunner because the phase amps are heavily capped. the controller itself will overheat while climbing a hill with a hub. You'll get bad efficiency and torque while climbing because you're effectively lugging this motor.

It's less power hungry than you think it would be because this motor is operating in it's peak efficiency zone per it's original design for scooter motors. I would chose a small-mid sized hub for hills over a mid drive in a 20" wheel any day of the week. Not just for power reasons, but also, regenerative braking ( v. important on a cargo bike wiht lots of hills x a lot of weight ).
 
Last edited:
laurentm said:
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.
Click to expand...

Switch baserunner to phaserunner for the controller on the Grin All Axle and then the peak torque gap closes up to only 5 Nm of the G60 with the baserunner. This while, more importantly, also making more power throughout the speed range.

Grin All Axle + Phaserunner is a faster and more efficient climber (compared to G60 with baserunner) even when I plug in 20% grade. This even when I set human power to 0 watts for both motors.
 
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Woa thanks to you both. What sort of battery capacity in amps should I look for with a similar setup?
 
As large as you can possibly get because you'll need to push some amps getting that heavy bike up the hill.
19ah or higher regardless of voltage.

For range reasons the ebikes.ca sim should be adequate for assessing that ^_^
 
It will technically work but notice due to inadequate amperage you're going slower and with worse efficiency on the fast winding.

The fast winding needs more amps per unit of torque made than the standard winding and both would be better served by the phaserunner.

We have no idea what bike you're using, it could have the aerodynamics of an upright mountain bike or probably worse.
 
neptronix said:
We have no idea what bike you're using, it could have the aerodynamics of an upright mountain bike or probably worse.
Click to expand...
It's an Xtracycle Edgerunner with 20" rear wheel:

1714095794052.png

And yes, aerodynamics is something not to forget about especially with the possibility of encountering a headwind while climbing a hill.
 
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Whoops..

With a 20" rear wheel i would not run a MAC then, they do horrible in 20" wheels, efficiency wise. Get a small DD.
 
Laurentm,

A chain is only as strong as it's weakest link.

The calculator is great for calculating loads on flat ground and uphill.....but it doesn't take into account headwinds.

Even a 10 mph headwind can almost double power consumption at 28 mph compared to no headwind.

So a good idea is to plan accordingly.

P.S. When using the ebikes.ca calculator I would expect the aerodynamics of a Xtracycle Edgerunner to be worse than "upright mtn bike".
 
Last edited:
laurentm said:
I just got a longtail cargo bike with a 20" rear wheel, the Edgerunner and I'd like to convert it to an ebike.
Click to expand...
Consider two hub motors. You can think of it as double the torque, effectively half the wheel diameter, or whatever. Longtails are very well weight balanced front to rear, so that's ideal for 2WD.
 
neptronix said:
A 20" wheel is where the all axle makes peak power and efficiency.

In your simulation you're running a baserunner which is providing nowhere near the amps required for that situation. The battery is sagging a ton also.

Motor Simulator - Tools

I suggest this scenario instead. You will get a sizeable increase in torque and efficiency.
If you have >4% grades then i would consider switching this motor for the RH212 fast winding and accepting the small extra weight.

This particular motor configuration maxes out the phaserunner's capabilities. The phaserunner taps out at 90A phase current but the motor could take 125A from a stop and burn rubber... :)
Click to expand...
Hey Neptronix.

This post has been nagging me for a while, and there may be something I don't get.
If I compare my initial build with your suggestion, I don't see an immense difference: Simulation

In a climb: 3 kph and 1 extra amp drawn from the battery with a phaserunner & 52v combination. Efficiencies seem fairly close. Am I misunderstanding the graphs or the tool? Or is this what you mean by sizeable increase?
 
I'm sorry, i'm wrong in this case.

The actual problem is that in this configuration the baserunner will eventually thermal throttle if the 5% grade is significantly long.
It's rated for a very low 55A phase continuous, 85A 'burst' and you will need to add significant heatsinking to it to make the 'burst' more 'continuous' as you're climbing hills with a very heavy bike here.

I would still recommend it's bigger brother for thermal reasons.
 
Ok, its clearer for me. Thank you so much for taking the time to answer :)

I gather this thermal question is not really possible to simulate using the tool?
 
Nah, the tool doesn't show controller heat buildup.
I'm pretty sure you'll have an issue with that, especially if you put the baserunner in a battery case.

Due to the higher amp handling of the phaserunner, you can expect it to run in non-thermally throttled mode most of the time.

Here's a hot baserunner versus a cold phaserunner's performance for a comparison. Very large difference in starting torque.

1714413681080.png
 
You get to the desired speed much quicker ^_^
 
I've been installing the All axle v3 this week with the baserunner. Y'all making me regret not getting a phase runner :)
 
You would have a pretty bad time with the fast winding, A totally OK ( but very efficient ) time with the standard winding.
 
neptronix said:
You would have a pretty bad time with the fast winding, A totally OK ( but very efficient ) time with the standard winding.
Click to expand...
Yeah I'm just hauling my kids around town at moderate speeds using pedal assist (not throttle) so hopefully it's sufficient. We have a few hills but nothing very long or steep.
 
Ah, multiple kids? you might find yourself wanting a stronger controller.
What wheel size do you have the motor in?
 
neptronix said:
Ah, multiple kids? you might find yourself wanting a stronger controller.
What wheel size do you have the motor in?
Click to expand...
Oh it's the same bike - Xtracycle Edgerunner. 20" rear wheel. 52v 20ah battery.

I was dead set on the cyc Photon originally but got sucked into the idea of a hub motor and Grin's products by a guy I went on a ride with.
 
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