Is there a planetary gear hub available?

[Joaquin Suavve]

Here is my thread that show what I was planning for them:

Introduction & Project Explanation

They are just the "raw" gears! You (or someone) would have to machine them into a usable gear reduction "package".

 

[lnanek]

Yeah, 30 tooth cog on the back seems huge:

I only ever use rear hub motors and 99% of the time I have an 11t cog in back and 75t in front. Keeping the throttle full and letting go of the brakes lets the motor handle accelerating from stop lights fine, so my gearing is only so I can get exercise pedaling at 30mph for the hour long commute to work instead of ghost pedaling.

I have zero interest in going above 30mph because cops already like to pace me and check if I'm pedaling, and would never mountain bike since I've broken a hip bicycling before so consider it too dangerous. So no need for a mid drive with exotic gearing for high speed or mountaineering here. Nice simple rear hubs all the way for me.

I do love how I can shift the Shimano IGH while at stop lights on my acoustic bike, though. Way better than derailleurs. Too bad my ebike has no need for shifting.

 

[Chalo]

Too bad my ebike has no need for shifting.

Every e-bike can use at least two gears: one for when the electrics are working, and one for when they're not.

 

[lnanek]

Technically there's some old Tourney 7 speed derailleur mounted that would work if I ripped the super tight chain guide off if really needed to get home after a battery dies.

I charge at work and keep a spare second battery on the rear rack, though. So unlikely. Going over bumps at 30mph without the chain guide was throwing the chain, so I happily gave up the gears to never have that happen again. I suppose a modern derailleur would have a clutch. I consider changing gears on my ebike an annoyance anyway, though, so only thing I'd be willing to upgrade to is an automatic like Enviolo offers or a CVT.

Worst case I'd just u-lock it to the nearest street sign, Uber home, and come rescue it with my car.

 

[amberwolf]

Every e-bike can use at least two gears: one for when the electrics are working, and one for when they're not.

That's assuming the pedals are going to provide any of the power input when the electrics are still working.

(I'd like to be able to do that on the SB Cruiser, but since it has to be geared so low that it's max speed via pedals only is maybe 1mph it would take a second stage of gearshifting (beyond the IGH and front chainring set) to get me a matching gear for 20mph motor powered speed).

 

[Chalo]

That's assuming the pedals are going to provide any of the power input when the electrics are still working.

(I'd like to be able to do that on the SB Cruiser, but since it has to be geared so low that it's max speed via pedals only is maybe 1mph it would take a second stage of gearshifting (beyond the IGH and front chainring set) to get me a matching gear for 20mph motor powered speed).

I recently adopted a Worksman PAV trike and put my old Crystalyte 5305 on the front. It has what looks like 32/20 gearing on a 24" drive wheel, so it's fit for its (very very slow) intended purpose. In effect, there's no overlap between the motorized speed range and the pedal only speed range. I thought for a brief moment about swapping in an IGH for the single speed coaster hub that transmits pedal power and braking to one of the rear wheels, but decided that the pedals were really only a self-rescue device.

 

[Hummina Shadeeba]

I’m hooked and still going to get this made. Tell me why I shouldn’t bother.

With a single planetary gear reduction can only fit 3:1 inside a 75mm shell. That’s even using needle bearings under the sun ( driven and on a floating shaft) and the 3 planets. Haven’t got a price yet or even the design finished but found places that will do the gears. Doing metal double helical gears. Will use a 14mm axle to fit common bmx frames. Will square the ends of the shaft (machined or maybe even glue a threaded block on the shaft) and use bolts on both sides of each dropout to clamp the axle to the dropouts and hopefully not need a torque arm. It’ll be peak 15Nm off the motor so assuming 45Nm going in and 135 output with the 3:1.



Doing double helical the design has to incorporate a way of assembling it. Doing a split ring seems the easiest.

These drawings just give an idea and not realistic, for example the yellow part will need to be two parts and a coupling so can fit a 24 id bearing on top that supports the shell and its ring.



Gears: 24t sun, 24t planets, 72t ring,16mm wide, module 1 size..so each tooth 1mm wide
Nylon would have to be so long for strength but the carrier for the planets is then greatly cantilevered and too risky. hub motors are doing 10-13mm long nylon


I’ll post the design and cost when I have it and see if anyone else is interested.

 

[lnanek]

Seems pointless when the Rohloff is already way above that at 130Nm max, so the market already offers better options. OK just to make it as artwork or a learning experience, I suppose.

 

[Hummina Shadeeba]

Seems pointless when the Rohloff is already way above that at 130Nm max, so the market already offers better options. OK just to make it as artwork or a learning experience, I suppose.

Those are expensive. This place has it half price and even that’s a lot:

Rohloff Disc Speedhub 500/14 CC E14 OEM 2 TS 148mm 32H Hub With Axle Plate | Merlin Cycles

Buy your Rohloff Disc Speedhub 500/14 CC E14 OEM 2 TS 148mm 32H Hub With Axle Plate at Merlin. Free worldwide delivery available on most items!

www.merlincycles.com

140Nm is just the limit of what the bike will put out using the motor I use, belt, n the hub id get made.
Don’t think rohloff get as high as 3:1 in relation to driving pulley.. and making it is fun. and want to use the 14mm axle get it lighter stronger smaller higher cheaper n hopefully quieter.

 

[lnanek]

Custom production is the opposite of cheap in my experience anyway. Bafang's 3 speed is only $128, and 5 speed is $349:

https://www.alibaba.com/product-detail/Bafang-Automatic-Gear-Hub-3-Speed_1601221189540.html

I don't think you are going to beat that. Half my Nexus hubs are just from the bicycle donation charity center next to work anyway. So if you only need one for personal use, you are also competing with non-profit used prices too, not new prices like above.

 

[Chalo]

and want to use the 14mm axle get it lighter stronger smaller higher cheaper n hopefully quieter.

I didn't think you understand what the bike's axle stud does. The stack diameter matters; the axle stud is just a fastener.

If you don't get that, you're way over your depth.

 

[Hummina Shadeeba]

Seems pointless when the Rohloff is already way above that at 130Nm max

This rohloff I assume is going to be able to take more torque than any of the others but it only claims 140 Nm. The motor puts out 15 Nm and then with a 3:1 belt coming off the motor and the hub doing 3:1 that 135 Nm and that’s assuming only a 3:1 belt off the motor to the hub. These available hubs can’t do the torque.

I didn't think you understand what the bike's axle stud does. The stack diameter matters; the axle stud is just a fastener.

If you don't get that, you're way over your depth.

I don’t get what ur saying. Im going to use a hollow 14mm axle. I think you’re saying when threaded it will get narrower.

 

[Chalo]

I'm saying that because the threaded axle end has the sole job of applying a constant tension preload, 14mm doesn't do that better than 10mm or 9.5mm. It's the stack of stuff from locknut to locknut (or shoulder to shoulder if the axle is monolithic) that matters for strength and stiffness. If you want more beef, you make that part bigger, not the threaded stud.

 

[lnanek]

Max torque from the biggest mid drive I know, Bafang BBSHD, is 160Nm. I prefer to ride with a 75t chainwheel and 11t rear cog, but the biggest chainwheel I know for the BBSHD is the Lekkie 52t. 160Nm / (52 / 11 ) = 34Nm torque on the rear hub. Bafang's 3 speed IGH is rated for 100Nm, 3 times more:


Seems fine.

 

[Hummina Shadeeba]

I’m not doing anymore “likes”. If ur writing anything related I like it.

14mm doesn't do that better than 10mm or 9.5mm. It's the stack of stuff from locknut to locknut (or shoulder to shoulder if the axle is monolithic) that matters for strength and stiffness.

So an axle nut inside the dropouts wouldn’t be much of a torque arm. I hadn’t thought of that.

I’m doing it 14mm because there’s cheap 26” bmx bikes with beefy horizontal dropouts

 

[Hummina Shadeeba]

Max torque from the biggest mid drive I know, Bafang BBSHD, is 160Nm. I prefer to ride with a 75t chainwheel and 11t rear cog, but the biggest chainwheel I know for the BBSHD is the Lekkie 52t. 160Nm / (52 / 11 ) = 34Nm torque on the rear hub. Bafang's 3 speed IGH is rated for 100Nm, 3 times more:
View attachment 371204

Seems fine.

I haven’t seen this IGH hub. But still only 100Nm and the gear ratios are small with 1.65 being biggest.

I also like a giant chainring, but not a small cog and this is 20t on front. (I’ve since found other cheaper big rings that use 3/16” chain on AliExpress .)

The simplicity of the belt straight back to the hub I like. Not simple in ways but nonetheless. Maybe will be lighter too.

 

[Chalo]

Max torque from the biggest mid drive I know, Bafang BBSHD, is 160Nm. I prefer to ride with a 75t chainwheel and 11t rear cog, but the biggest chainwheel I know for the BBSHD is the Lekkie 52t. 160Nm / (52 / 11 ) = 34Nm torque on the rear hub.

BBSHD power through an 11t sprocket seems like a terrible mistake. Those things barely work with muscle power, and only do the job because they're called upon so infrequently. There are reasons that bikes with chains were ridden competitively for 100 years before people forgot engineering basics enough to start using 11 tooth sprockets.

How many miles do you get before the chain and/or 11t sprocket is knackered?

 

[Hummina Shadeeba]

250Nm “at the cranks”?

I’m wondering where these other hubs are measuring their rated torque because 250Nm before even the chain or belt to the back and then another reduction in the hub will produce some crazy torque at the wheel (although this guy in the video has a tiny pulley on the wheel and so does the pic and the purpose isn’t the same).

Also expensive. I’m confused by its gearing ratios and still might not be close to 3:1. It’s only 32 spokes and they should do 36 with the claimed torque ability

 

[lnanek]

Checking their site, that system has a 44t front and 15t rear, so 250Nm at the crank would just be 85Nm on the hub:

Revolute

www.revolute.de

Hummina's system looks like ghost pedaling city to me. I think I'd just throw that motor out and get one with a more appropriate winding at that point. Or just remove the cranks and put pegs on.

 

[Hummina Shadeeba]

Checking their site, that system has a 44t front and 15t rear, so 250Nm at the crank would just be 85Nm on the hub:
View attachment 371210View attachment 371211

Revolute

www.revolute.de

Hummina's system looks like ghost pedaling city to me. I think I'd just throw that motor out and get one with a more appropriate winding at that point. Or just remove the cranks and put pegs on.

So you and they arent trying to get more torque with the gearing and different goal. With the igh I’d make it’ll have threading to mount a freewheel on the other side and could use a giant chainring, as a chainring, and pedal while riding but likely won’t.
Pedaling is purely backup on my bike now and it would be the same with using this hub for me.. but you could do a giant chainring n assist like youd like.