is geared hub motor feasible in a 20-inch rim?

[neptronix]

Im assuming a hub with gearing, despite having less room for actual motor, generally runs cooler given the same load than without a gear.

Runs cooler but can dissipate 1/3rd of the heat of a DD.

There’s no hub motor with strong steel quiet internal gears available?

Never heard of such a thing, in order to be quiet, steel gears would have to be in some kind of lubricant bath. I've never seen such a thing for sale in my history here.

Maybe with the planetary gear heat transfer is further obstructed?

I dunno, i imagine the gear carrier helps collect some of the heat. That's about all it does.

 

[Papa]

Mid drives have gears that are able to survive the max motor torque and I see no reason a hub motor’s gearing shouldn’t be able to do the same.

Do you posses proof they don't (assuming manufactures recommended voltage is adhered to)?

Reality is, gear hubs are prone to failure.... when users exceed the motor's rated voltage.

 

[Hummina Shadeeba]

Do you posses proof they don't (assuming manufactures recommended voltage is adhered to)?

Reality is, gear hubs are prone to failure.... when users exceed the motor's rated voltage.

I read about the nylon gears melting. I thought was the current.


Herringbone gears could be quiet

 

[amberwolf]

I read about the nylon gears melting. I thought was the current.

There's a number of reasons for gears of any kind to be damaged; there's posts over the years discussing, showing, and sometimes testing various damage scenarios for the common plastic types of gears in hubmotors and the reasons they happen.

Which specific scenario are you referring to, for melting nylon gears?


FWIW, current (amps) won't melt them, as they aren't conductive and aren't in the current path anyway. (perhaps if you had voltages across them somehow, like lightning, that enabled current flow thru normally insulating materials, but I doubt that's your scenario).

Heat generated by current that overheats the motor could melt them if that heat increases beyond their melting point. But you wouldn't want to overheat the motor anyway, so they shouldn't be melting in a normal use situation.

Etc.

 

[Hummina Shadeeba]

I read it somewhere on here gears melted.


More so im interested in how durable gears are because the qs138 motor I have is making a whirring noise. I’ve been putting more amps in than it’s intended. I see they updated the qs138 with bigger bearings but no change to the gears which is encouraging.

 

[amberwolf]

I read it somewhere on here gears melted.

Yes, as I said before:

There's a number of reasons for gears of any kind to be damaged; there's posts over the years discussing, showing, and sometimes testing various damage scenarios for the common plastic types of gears in hubmotors and the reasons they happen.

Which specific scenario are you referring to, for melting nylon gears?

 

[Hummina Shadeeba]

Yes, as I said before:

There's a number of reasons for gears of any kind to be damaged; there's posts over the years discussing, showing, and sometimes testing various damage scenarios for the common plastic types of gears in hubmotors and the reasons they happen.

Which specific scenario are you referring to, for melting nylon gears?

I don’t remember what I read but the nylon gears can’t take what the motor can put out. I see there’s a thread on es about replacement metal gears for hub motors. Just seems a shame to be limited by the gearing where if the gears where metal I think would be capable

 

[Chalo]

I don’t remember what I read but the nylon gears can’t take what the motor can put out. I see there’s a thread on es about replacement metal gears for hub motors. Just seems a shame to be limited by the gearing where if the gears where metal I think would be capable

Metal gears chew up the gears they mesh with, unless they run in an oil bath (and sometimes despite this). Nylon gears can serve as a structural fuse that fails before something more difficult or expensive gets pushed past its limit.

I guarantee you don't understand the principles at work as much as the folks who decided to put nylon gears in there. You can make faulty assumptions all you like, but if you swap for steel gears instead, you will find out why they weren't there all along.

Steel gears are a popular swap for nylon gears in Cyclone 2-4kW gearmotors that are used in pedicabs around here. They always wreck the steel gear on the motor output shaft. It might be worth it for working riders to reduce down time, but it complicates later repair and hastens the replacement of the whole motor.

 

[DaLanMan]

I kind of audited a class on electronic repair/installation (my window was next to the classrooms so I heard the lectures on the regular) It was a class for people going to work for a vehicle maintenance company.

During the discussion about over-fusing (installing additonal fuses on existent wiring) they were discussing that for some brands/models of vehicles there is a standard practice of installing a secondary line fuse on the load side near the load itself. When asked why they put in a smaller/weaker fuse than is upstream in the loom.

The answer has served me well in many many things.

"We do this because the fuse was set based on the standards of engineering, not on the fact that the motor (load) often is used exceeding spec, hence it is going to burn off a fuse. Fuses are not a problem, easy to replace, and gauranteed to protect the upstream portion of things.
In our case however the thing we are protecting is time. It take between 8 and 14 hours to replace the wire from the loom exit to where the motor is mounted. The fuse we are adding protects the time lost in replacing that wire. If you do not choose where things will break, the items themselves will. They are all evil and in the service to Murphy"

So when you are poo-pooing the engineering choices of something, look around, if *ALL* of the items on the market do the same thing they are all either unthinking knock-offs, or they are protecting the thing most desirous of protection. Time and money. The time in dealing with failed units, and the monetary losses caused by users doing things you can't prove during the period where the unit is still in warranty. If you are in agreement with the engineering decisions you are in a good place. First know what they are doing and why. Then make a judgement call.

 

[mindgames11]

I don’t remember what I read but the nylon gears can’t take what the motor can put out. I see there’s a thread on es about replacement metal gears for hub motors. Just seems a shame to be limited by the gearing where if the gears where metal I think would be capable

there are after-market products for all sorts of things that aren't necessarily "problems". take automotive- millions of "upgrade" parts that "solve" things for people who were using their vehicles foolishly or simply expecting them to operate outside the parameters they were designed for.
I like spirited driving sometimes, but I never let my vehicle hit the rev limiter and almost never enter the red upper end of the tach, in fact making it a practice never to exceed 5,700 on my BMW M54 engine.

I recently got a geared hub bike. havent yet ridden it so I don't have an opinion on their characteristics, but if the use of nylon planetary gears is the limiting factor... well it is a bicycle, not a motorbike and direct drive motors exist. If I find that hub motors (generally, or mine specifically) are for my tastes too limited in their abilities and the reason being the use of nylon... well, then I would be in relative agreement with you, although I would say that I believe I'd be aware that my disappointment is due to my expectations exceeding what I payed, or the realities of consumer manufactured products.

 

[marka-ee]

With Tadpole trikes, your geometry & steering is essential for decent control at speed. ANY error in Ackerman, tracking, frame flex, or front to rear weight balance is going to effect your handling, braking & control. The faster you go, the more these deficiencies will show themselves. Riding a Tadpole trike at a constant 30 mph is not something that is enjoyable unless you have a sophisticated suspension system. Take a look at HP Velotechik Scorpion, Azub Ti-Fly, Steintrikes Wild One & those suspension systems will give you an idea of how much engineering goes into a good suspension & steering system. For a home built unit I would go with your 500 or 750 watt geared motor (Mid Drive or Hub) as they both have Pros & Cons. You might not hit your constant 30 mph but will probably find your trike is a handful at a little slower speed anyway.

For what it's worth, it's not a home-built trike. It's actually a Optima Rhino FS, which is full suspension but not the terribly fancy kind with double A arms on the front however it does ride very well from what I can tell. They only made a few dozen of them. When I get the time I'm going to solve the voltage sag problem that I was getting when I was testing with a direct drive 20 inch on the rear and I think it will reach about 40 kilometers an hour then, which may be enough. However, if it's not, I have a MY1020 type motor which I would then do a single stage belt drive to a very large toothed belt pulley which would be almost the same size as the rear rim. A 3D printed pulley would be attached to the side of the rim as per a few of the YouTube videos I've watched. I'm shying away from any kind of mid drive because driving the extremely long chain to a derailleur just seems wrong to me in some way. I live in a pretty much flat area as well.