Where are the hq geared hub motors?

qwerkus

10 kW
Joined
Jul 22, 2017
Messages
785
I'm wondering why there are no geared hub motors available, with really good industry grade gears inside. All we have are crappy nylon + steel gears with tolerances up to a mm! I keep reading everwhere that the problem is noise, but this is not necessarly true. If you take quality gears (like neugart %co), you can have 10 000 rpm BLDC motors with 10:1 planetary reductions which are well lubricated, well sealed and barely audible from 1.5m.

The clue is helical or even hypoid gears, perfect match, zero tolerance, good bearings and proper lubrication. It should be possible to make 3Kg motors, with gears able to handle 100 n.m or more @1000-1500W without stripping immediatly. Than comes the cooling issue, that's another question.

I understand this would mean extra costs, yet there are many cases in which hub motors still beat mid drive (MAINTENANCE!) and where people would be ready to pay a premium to have good gears.
 
Interesting find - but 5.2Kg! WTF - that's more than some DD motors out there known to be able to handle 1000W. Going to ask heinzmann about more details.
 
qwerkus said:
Interesting find - but 5.2Kg! WTF - that's more than some DD motors out there known to be able to handle 1000W. Going to ask heinzmann about more details.

A better hub is a heavier hub, mostly.
Lucky you care about gears and bearing and construction quality.
If you would care about power and speed, double the weight wouldn’t be enough.
 
MACs today are nearly perfect geared motors, and the stator itself has the thinnest laminations ever seen in any hub motor to keep the cooling issue at bay as much as possible, and the gears/clutch have gone through almost a dozen revisions for strength.

The real limit for geared motors is thermal issues, not gears. If you were to make a liquid cooled geared motor, then maybe the gear design could be the final last weak point to solve. Then, a 2 stage reduction would come standard and power densities would skyrocket.

But the question is.. how many people would buy a ~$500 2kw 4kg liquid cooled geared hub with dual reductions? I know i would.. it would lay the smack down on mid drives in every way. But it could only be sold to a small niche market here in the USA. What manufacturer wants to spend all that R&D time making the dream motor? seems like all the R&D has been shifted to mid drives, which imho is a sad state of affairs, because there's still a great use case for hub motors and their simplicity.
 
neptronix said:
MACs today are nearly perfect geared motors, and the stator itself has the thinnest laminations ever seen in any hub motor to keep the cooling issue at bay as much as possible, and the gears/clutch have gone through almost a dozen revisions for strength.

The real limit for geared motors is thermal issues, not gears. If you were to make a liquid cooled geared motor, then maybe the gear design could be the final last weak point to solve. Then, a 2 stage reduction would come standard and power densities would skyrocket.

But the question is.. how many people would buy a ~$500 2kw 4kg liquid cooled geared hub with dual reductions? I know i would.. it would lay the smack down on mid drives in every way. But it could only be sold to a small niche market here in the USA. What manufacturer wants to spend all that R&D time making the dream motor? seems like all the R&D has been shifted to mid drives, which imho is a sad state of affairs, because there's still a great use case for hub motors and their simplicity.

Right to the point - exactly my conclusion. I actually wrote to macmotortech about a possible second stage reduction, but did not get an answer ... yet. You're probably right about the mid drive hype, but at least in europe, there is a growing market for cargo bikes. As more and more cities introduce effective carbon taxes and drive bans on diesel, the sector is literally exploding, not to mention the difficulty to park a delivery car in overcrowded cities centers.

That's probably why Heinzmann came up with that heavy motor (which is oil-cooled btw - at least according to the specs). The reason is pretty simple: mid drive cargo is a no go. Wayyy too many parts that brake and effectively limited in the power output. I'm going to look into the cooling issue, maybe add a simple oil-to-air-radiator circuit. Still it does not solve the problem of high quality gears. I contacted a few names in germany, but they do not seem eager to enter the hub motor market. Maybe I should ask rohloff or pinion if they can broker the manufacture of a few quality gear sets for me, but that's gonna $$$$
 
neptronix said:
MACs today are nearly perfect geared motors, and the stator itself has the thinnest laminations ever seen in any hub motor to keep the cooling issue at bay as much as possible, and the gears/clutch have gone through almost a dozen revisions for strength.

The real limit for geared motors is thermal issues, not gears. If you were to make a liquid cooled geared motor, then maybe the gear design could be the final last weak point to solve. Then, a 2 stage reduction would come standard and power densities would skyrocket.

But the question is.. how many people would buy a ~$500 2kw 4kg liquid cooled geared hub with dual reductions? I know i would.. it would lay the smack down on mid drives in every way. But it could only be sold to a small niche market here in the USA. What manufacturer wants to spend all that R&D time making the dream motor? seems like all the R&D has been shifted to mid drives, which imho is a sad state of affairs, because there's still a great use case for hub motors and their simplicity.
YES! Take my money! PLEASE!
 
You have three options.

1) MAC with an ATF fill, but weld the clutch because it *will* break at higher power levels.
2) forget hubs and do a direct rear chain drive.
3) A high efficiency DD with 0.35mm laminations.. IE the leafbike 1500w, MXUS 3kw, cromotor, etc.

I have also been trying to bust MAC's balls for a while, because i knew they were testing a motor with a double width stator. They actually built a few prototypes of this motor, but realized the gears wouldn't stand up to the task. OK, so shrink the stator a bit and put some beefier gears in there i say, but they just haven't gotten around to it.
So i think we are not likely to see a dual reduction motor from them.

Just recently i sent an email to leafbike suggesting they put 0.27mm laminations in their DD hub. It could be a true 2000w motor instead of a ~1800w motor with this change. They did receive the email and said thanks for the idea, but who knows about the follow through. Such a motor would have a higher efficiency all around, thus climbing a few hills on a cargo bike wouldn't be a big deal ( or going stupid fast on the flats! ).

We could absolutely have higher power density in hub motors. The bafang G310 is a shining example of packing a ton of power in a small size. Yeah, it's a total shame that power density still goes by the wayside for larger motors.
 
If I were to buy a geared motor, the MAC is the one I'd buy but I do love the d.d. MXUS. Still going strong. Had to replace one bearing and hall sensors a few times because of my fault.

For a new motor/design perhaps we get a petition together and send it to 2 producers.

Another option is to build our own. Order in the parts and assemble.
The only major hurdle would be the dipped laminations and having a non axled stator. Get a local machine shop to one off an axle or get BlueSaw to do them and mail them out along with rotor magnet ring and covers.

A design where a simple cover plate would be ideal, to cut costs, then if others want a ridge for sealing get it done locally.

The hard part, winding the magnet wire. Perhaps the savings in worth it?

- Forgot to add the dipping of the wire.
https://www.youtube.com/watch?v=yPwf3BwS4pg

I tried to find the thread where we talked about doing that a year or more ago.
This may be it - https://endless-sphere.com/forums/viewtopic.php?f=30&t=57371&p=859662&hilit=custom+motor#p859662
 
Well, I don't believe in petitioning producers. But what seems doable it taking the fast mac as it is, redo the 2 side panels to add more depth and squeeze in a dual reduction. I'd still have to find a company making quality gears + bearing. The rest seems only lathe work and doable, given enough time. Final motor should be around 120mm wide.
 
I'm all for a petition. You start it up, and i'll be your wingman. I have contacts at MAC and can forward on the result.
 
neptronix said:
I'm all for a petition. You start it up, and i'll be your wingman. I have contacts at MAC and can forward on the result.

LOL, macmotortech just wrote me they are working on a 2x gear prototype.
 
Do you mean double reductions, or double the stator?

Cuz i've heard of the double width stator motor since 2012.
 
Are the gears a problem? I've seen photos where they failed in over-heated hubs, but how important is it to make gears that are fine but the magnets are ruined?

Metal gears could handle more torque, but more torque means more heat, and the heat path in geared hubs is worse than DD hubs.

The Aikema Q128H double reduction gears are good for its 50N-m of torque, the reason you can't run too long at that torque is because a geared hub can't shed the heat.

I'm not seeing that the gears are the weak spot.
 
I've been rebuilding 2 MACs for my AWD Fatty. Standard Stator and runner, standard gears (but greased with Aeroshell), and with a beefy clutch (up to 170Nm). It has a side entry motor cable and internal gear & temp sensor. Heavy duty use, so far no problem.
Been tinkering with the idea of a 2-speed hub, adding a crawl gear with max 8-10 kmh.
MACs are excellent motors with room for improvement.
 
neptronix said:
Do you mean double reductions, or double the stator?

Cuz i've heard of the double width stator motor since 2012.

The term used is "2 gear reduction" but i could not get any ETA.
 
Because hub motors in general suck due to adding mass in the worst possible place and it's not worth making expensive high end geared hubs. It would be too much of a niche product and by the time you get around making everything decent quality and in low volume it will cost over twice as much.

Basically, high power DD hubs are good enough for easy hot rodding, all others go custom mid drive and / or get a motorcycle.
 
The worst possible place would be on the handlebars, i think :)
A motor in the rear wheel is the second best place to put it. A motorcycle shows us where the absolute best place for a motor is.

Hubs are not bad; they're better than mid drives for some situations.
Mid drives are better than hubs in others.

It just depends on your use case.
 
flat tire said:
Because hub motors in general suck due to adding mass in the worst possible place and it's not worth making expensive high end geared hubs. It would be too much of a niche product and by the time you get around making everything decent quality and in low volume it will cost over twice as much.

Basically, high power DD hubs are good enough for easy hot rodding, all others go custom mid drive and / or get a motorcycle.g
If you want an ebike that rides like a bike, and doesn't add drag if you are pedaling without assist, geared hubs with good power that weigh 2kg are available.

Prices are low because they aren't niche at all, they are made by the millions because they are reliable.

Quality is high because they are mass-produced and design is highly optimized.

Hobbyists hot-tod them, and pushed beyond the design intent they aren't as reliable, same as if you hot-rod a car.

If you want sustained high power from a hub motor and don't mind drag because you want assist all time, a 5kg DD hubs and a heavy battery are available.

If you want a bike that is light and feels like a bike, has assist when you need it but doesn't add drag when you don't, a geared hub with a light battery is a better choice.
 
electricwheels.de said:
I've been rebuilding 2 MACs for my AWD Fatty. Standard Stator and runner, standard gears (but greased with Aeroshell), and with a beefy clutch (up to 170Nm). It has a side entry motor cable and internal gear & temp sensor. Heavy duty use, so far no problem.
Been tinkering with the idea of a 2-speed hub, adding a crawl gear with max 8-10 kmh.
MACs are excellent motors with room for improvement.

You are thinking of making your own 2-speed? Similar concept as the Xiongda 2-speed? That's cool, more details?
 
Guys, I've been writing to macmotortech, and they seem open to custom jobs. They even sent me a cad file of the motor to mark the improvements I'd like. One off is probably not worth it - anyone interested in joining the project ? My requirements are: large axle (20mm) which means 65mm Rohloff disc rotor mounts, bolts for single sided mounting (trike) and dual reduction. Also, I'd remove the clutch to allow for regen and backwards drive, and use the gained space to add the 2nd gear.
 
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