Best geared motor for heavy duty use (cargo bike) ?

Jil · Jul 26, 2022

Hi !

I'm currently doing a survey about what motor choosing for a future cargo bike, intended for commercial use : long-john type, capability to haul 250 kg (all-in weight) on a 15% grade, 25 kph max speed (EU limit).
A similary subject has been discussed here : https://endless-sphere.com/forums/viewtopic.php?f=3&t=115851&hilit=cargo

I'm considering both DD and geared motors. As far as DD are concerned, the Grin All-Axle or FH212 with Statorade seem to be a good option, on the 20" front wheel.

I'm considering also the option to use a geared motor, preferably on the rear wheel (26 or 28").
The Heinzmann CargoPower RN111, with regen, metal gears and oil cooling, seems the best candidate among the geared motors I have reviewed, but it has a major downside for me : it's loud.
See at 22"00 :
https://youtu.be/a7x1APfGdyg

The GMAC is an option, relatively silent and with regen, but on long climbs it overheats quite quickly, because of the lack of oil cooling.

Does anything equivalent (and quieter) to the Heinzmann exist on the market ? The price is not decisive, I'm looking for quality, durability (minimal maintenance) and silence.

Thanks

offGridDownUnder · Jul 29, 2022

Hello,

I put a Grin All-Axle (fast-wind 20") on the front wheel of my commuting folder (now sold), as well as the rear wheel (slow-wind 26") of my Cruzbike Q45.

The motor has the power, but on the front wheel, on ascending hills, the tire does not have the grip. Yes, I could alleviate the problem by adding power to the rear wheel by pedaling, but that only relieves the problem - I still had an expensive tire-scrubber if I wasn't thoughtful with the throttle and gears. Riding solely by PAS (cadence sensor on the bottom bracket, and no throttle input) the tire did not scrub, but if the power level were high enough it might have. The commuter had stock 2.13" Big Apple tires.

With the drive wheel at the rear of the Cruzbike, there is no slip, and I can accelerate when I'm partway up a hill - although if I'm slow or stopped there are hills that also require pedal input.

For commuting and general riding, I don't think front hubs have any drawbacks, but your use case is heavy loads up hills. Unless someone knows a trick I don't, I would say a front hub has a natural disadvantage in that case.

For the rear, how about the eZee? I haven't used them, just mentioning.

offGridDownUnder · Jul 30, 2022

Jil said:
I'm considering both DD and geared motors. As far as DD are concerned, the Grin All-Axle or FH212 with Statorade seem to be a good option, on the 20" front wheel.

Also, Grin is working on a version of their All-Axle with a cassette freewheel for use as the drive wheel. I ride a Cruzbike (back to front recumbent) so their 'front' motor serves me well on the back of my bike. The new 'rear' version will avoid the traction problems I mentioned above when used as the drive wheel on a conventional upright bicycle.

In my case, one of their 'rear' motors can substitute for my front wheel and by setting the regen parameters properly, I can recharge my battery by 'riding' the bike on a stand at home. I do this now when the weather is bad - charging the battery with my effort is a bonus.

Also, if I have this, two All-Axles on the bike will get me and my trailer up any hill.

I asked, they won't tell me when, but do assure me it is in the works. Given that you are asking about a future use, you might keep this in mind.

Chalo · Jul 30, 2022

sadhak said:
I can recharge my battery by 'riding' the bike on a stand at home. I do this now when the weather is bad - charging the battery with my effort is a bonus.

Give up on this dumb idea right now. It's not going to happen. Unless you want to sweat for hours inside to sock away one lit fart worth of energy (and you don't), it's a waste of time and effort.

offGridDownUnder · Jul 30, 2022

Chalo said:
sadhak said:

I can recharge my battery by 'riding' the bike on a stand at home. I do this now when the weather is bad - charging the battery with my effort is a bonus.

Click to expand...

Give up on this dumb idea right now.

Reply from Grin tech support in response to my question:

When using the controller to dial in the regen, you can simply set it to a value that is achievable. Monitoring via the CA would allow you to simply watch as the Ah went backwards.

What I can't specifically tell you is the efficiency of the system.

We can assume that:
chains are ~95% efficient if in good maintenance
motors are ~85% efficient
motor controllers are ~90% efficient

Total system efficiency would be ~73%, so you'd need to put in ~192Wh to get ~140Wh.. So if you can put in 100W mechanically, you can expect ~2hrs to recover that 140Wh.

We'd want to choose a motor that had the best ratio of core losses to peddling RPM, so a geared motor, if spun slowly can actually be really efficient. I'd start with just what you have though, and play around there to see if you want to optimize, or just make what you have work for you.

My current usage is ~7Wh/km, and 20km of travel then uses ~140Wh. This is the scenario I asked them about in order to gauge the viability of the approach, and the source of the numbers they referred to in their reply.

I would like to hear actual numbers from an actual implementation you have done - can you supply that please? Perhaps in another thread, as this one is about motors for heavy duty use. I have several, or you could start one.

Chalo · Jul 30, 2022

I can tell you that I built a stationary cycle to power a couple of compact fluorescent light bulbs and a laptop computer, and nobody who got on it was willing to hold the load for very long. Certainly not two hours.

https://artdaily.cc/news/29378/Art-Alliance-Austin-Reveals-2009-Commissioned-Artist-Project-Jaclyn-Pryor-s-Pink--unplugged-

You can think it's a good idea, but somewhere in the first hour you'll already have decided against it. But you don't have to take my word for it....

Jil · Jul 30, 2022

sadhak said:
Hello,

I put a Grin All-Axle (fast-wind 20") on the front wheel of my commuting folder (now sold), as well as the rear wheel (slow-wind 26") of my Cruzbike Q45.

The motor has the power, but on the front wheel, on ascending hills, the tire does not have the grip. Yes, I could alleviate the problem by adding power to the rear wheel by pedaling, but that only relieves the problem - I still had an expensive tire-scrubber if I wasn't thoughtful with the throttle and gears. Riding solely by PAS (cadence sensor on the bottom bracket, and no throttle input) the tire did not scrub, but if the power level were high enough it might have. The commuter had stock 2.13" Big Apple tires.

With the drive wheel at the rear of the Cruzbike, there is no slip, and I can accelerate when I'm partway up a hill - although if I'm slow or stopped there are hills that also require pedal input.

For commuting and general riding, I don't think front hubs have any drawbacks, but your use case is heavy loads up hills. Unless someone knows a trick I don't, I would say a front hub has a natural disadvantage in that case.

For the rear, how about the eZee? I haven't used them, just mentioning.

Thank you Sadhak for this useful input !
On my case I want to use it only with PAS. Throttle use limited to help me starting up to 6 kph.
Rear could be an option, but from the Grin simulator it would overheat quite quickly for my need.

Best geared motor for heavy duty use (cargo bike) ?

Jil

1 kW

offGridDownUnder

1 kW

offGridDownUnder

1 kW

Chalo

100 TW

offGridDownUnder

1 kW

Chalo

100 TW

Jil

1 kW

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