Is there a planetary gear hub available?

[Hummina Shadeeba]

Is there a non-motorized planetary gear hub can take a sprocket?

Like this below but with a bigger gear ratio and stronger for being driven by some available mid drive motor

Review: Sturmey Archer S3X: Three Speed Fixed Gear

Like the fixed gear, but don’t like the hills? Sturmey Archer SX3 to the rescue. I picked mine up from Ben’s Cycle, which sells the hub for $179.00. The S3X is much different than most…

overthebarsinmilwaukee.wordpress.com

A burly one would really open up the potential for mid drives

 

[offGridDownUnder]

Is there a non-motorized planetary gear hub can take a sprocket?

Like this below but with a bigger gear ratio and stronger for being driven by some available mid drive motor

Review: Sturmey Archer S3X: Three Speed Fixed Gear

Like the fixed gear, but don’t like the hills? Sturmey Archer SX3 to the rescue. I picked mine up from Ben’s Cycle, which sells the hub for $179.00. The S3X is much different than most…

overthebarsinmilwaukee.wordpress.com

A burly one would really open up the potential for mid drives

Shimano Nexus or Alfine?

Internal-Gear Hubs

How about the Enviolo?

 

[Hummina Shadeeba]

I imagine none of those are up to the challenge of a common mid-drive motor pulling the chain and they would break. No?

The multiple gears maybe would be nice but not necessary and I’d be happy with one 4:1 ratio that wouldn’t break.

 

[offGridDownUnder]

a common mid-drive motor

You haven't specified the motor, so not possible to say. Some mid-drives and internal gear hub combinations are endorsed by the manufacturers.

Hummina, you've been posting and reading here for quite some time. Why are you asking questions without supplying what you know are the details needed to answer the question?

 

[Hummina Shadeeba]

You haven't specified the motor, so not possible to say. Some mid-drives and internal gear hub combinations are endorsed by the manufacturers.

Hummina, you've been posting and reading here for quite some time. Why are you asking questions without supplying what you know are the details needed to answer the question?

I’ve never seen a hub with an internal gear for use with any type of external mid drive motor. Are there options?

I’d use it with something like this:

https://a.aliexpress.com/_mKxerKJ

(Zoinks the cost is double)

I don’t have a plan to do anything at this point and wondering if such a hub exists

 

[Chalo]

I’ve never seen a hub with an internal gear for use with any type of external mid drive motor. Are there options?

3X3 Nine makes one. Shimano makes a heavy duty 5 speed hub for e-bikes. Some of the Nuvinci and Enviolo models can tolerate motor power, and so can Rohloff Speedhub within its torque limits. Usually there's either a maximum input torque or a minimum input gear ratio rating that applies to the external sprocket drive. So you can use motor power, but you can't gear it down willy-nilly.

I wouldn't expect any Sturmey Archer hub to thrive with greater than human power through its gears.

 

[Hummina Shadeeba]

Other than using like a 150t rear sprocket or a motor happening to have internal gearing a geared hub seems a good option except what’s available is expensive and I only want one really strong gear.

I’m interested in getting a one-speed geared hub made. Do you know a good design I could model off of or have any advice for the design?






I’m thinking of doing a 14mm rear axle to fit bmx bikes. 36 spokes. About 4:1

 

[offGridDownUnder]

any advice

You mention a 4:1 ratio in an earlier post. Can you say what the range of input : output ratios you would accept?

If you never shift it, I suspect any of the ones mentioned above would handle the torque - perhaps that's not so?

Do you have some basis for knowing the cost of having one custom made? Of course, you may be asking for reference designs so you can ask for an estimate in the first place. Just checking.

 

[Hummina Shadeeba]

You mention a 4:1 ratio in an earlier post. Can you say what the range of input : output ratios you would accept?

If you never shift it, I suspect any of the ones mentioned above would handle the torque - perhaps that's not so?

Do you have some basis for knowing the cost of having one custom made?

a bigger ratio at like 6:1 might be better. The basis for choosing would be eddy current production in the motor and how thin its laminations are and would want to spin it like a maniac. I’d rather not have to use a giant rear sprocket or a small front.

Maybe those hubs would work but I’d rather get a simple one made anyway with a bolt on (hollow)14mm axle for bmx bikes and a single indestructible gear, or maybe two gears depending how complex it would be.


Basis for cost.. I doubt would be more than 3 or 4 hundred bucks including shipping based on other parts I’ve had machined. If had a lot made the price goes down hugely. Yea I dont have a design to show for a quote yet.

 

[lnanek]

Feels like it would be pretty easy to take a Nexus IGH apart for "servicing" and just use JB Weld instead of grease to restrict it to only one gear. Usually a shift cable causes more or less pawls to pop out of a shaft, so you just need to lock them in a set configuration.

A lot like how people convert geared rear hub motors to direct drive by welding the clutch to enable regenerative braking. A modified mass produced item will likely be cheaper than something custom. A lot of people also weld the roller brake off on IGH that have them, so theoretically you could get an IGH with a roller brake, weld it to always be on, then attach a cog to what's usually the torque arm locked to the chain stay to prevent rotation.

The Freegen folks also have modified motors in the past to attach a brake rotor to the planet carrier of a rear hub motor instead of the shell. I feel like it would be cheap to grab a broken geared rear hub motor, strip out the motor parts, then attach a cog to the planet carrier instead of a brake rotor.

Kind of all super messy compared to just an idler shaft with two different size cogs on it sitting in-between the motor and the rear wheel, though. Chain one goes from mid drive to cog one on the idler shaft, chain two goes from cog two on the idler shaft to the rear cassette. Change the cog teeth on either cog on the idler to change the gearing. Having this extra leg in the chain line is popular with full suspension bikes right now anyway because it also lets you move the idler shaft to the location of the suspension pivot so the chain length doesn't change with squat. So it wouldn't even be wasted having one.

 

[offGridDownUnder]

attach a cog to the planet carrier instead of a brake rotor.

FWIW, on my trike (Greenspeed Magnum Big Wheel - below in sig) I have my Grin motor mounted behind the seat and the chain goes to the cassette there, the output is a Gates 26T (or 22T) sprocket mounted to the 6 bolt ISO brake rotor mount on the left side of the motor, and that belt goes to a Gates sprocket (currently 48T, but changeable) on the 6 bolt ISO brake rotor mount on the left side of the rear hub with a custom spider (6mm Al plate) to mate the 104mm BCD or 130mm BCD chainring to the hub.

If you insist on chain, there are track sprockets that mate to ISO brake mountings and chainrings are standards, in case that helps.

 

[Hummina Shadeeba]

I haven’t looked much but all the available hubs have low (or fivking high..the terminology I’m confused) gear ratios at not even 3:1. Im trying to beat all the Ducati from the red light with a 14mm axle bmx bike. I need like 12:1 and a low slung battery n drop bars and the longest frame size.


If only there was a way to cool a hub motor as well as mid-drive. What’s the best cooling mid drive motor ?

 

[Chalo]

Im trying to beat all the Ducati from the red light with a 14mm axle bmx bike.

You won't be doing that with bicycle parts, then. Look for an aftermarket motocross hub with a disc rotor mount on one side and a sprocket mount on the other. Then look at making frame ends that accept a through axle.

If you try to use bicycle parts for this job, you'll either break them or slip them out of engagement, or both. A performance grade bike is engineered for about 200W continuous pedal power and maybe 1000-1500W in brief bursts. And it's built to be light and simple, not to have 10X or more of safety margin built in.

"Win stupid prizes" is still something you can do if you really need to.

 

[Hummina Shadeeba]

You won't be doing that with bicycle parts

I think a bmx frame and 14mm axle won’t break. Maybe a 26” bicycle wheel with 36 spokes can’t survive such torque. I’m somewhat joking though trying to beat all the Ducati from the light but I think even a small mid drive connected by chain to a 12:1 geared hub possibly could if it wouldn’t flip.


It’s a shame not to have the available gearing to utilize the potential of the motor and they all can go many more rpm than done.
I’m undeterred in my goal of getting this 110mm spacing bmx hub made.

 

[Chalo]

I think a bmx frame and 14mm axle won’t break.

Assuming that's true, how do you propose to keep the axle from slipping forward in a horizontal slot? If you use something other than a hefty motorcycle sprocket, how do you propose to prevent bending or folding it? Keep in mind that however much thrust you get on takeoff will be increased by the ratio of wheel size to sprocket diameter, and then exerted on the sprocket side dropout slot.

Maybe a 26” bicycle wheel with 36 spokes can’t survive such torque.

The wheel would be fine, but the freehub or threads for the freewheel might not.

It’s a shame not to have the available gearing to utilize the potential of the motor and they all can go many more rpm than done.

Yeah, it would be super cool if somebody developed a box full of gears that could take a high motor RPM on the input, and convert it to a lower RPM on the output. I should look into that.

 

[Hummina Shadeeba]

Yeah, it would be super cool if somebody developed a box full of gears

Ur teasing but I don’t want to use a gear box. It adds complexity and have to use a bigger chain.


…even 1:6 would be good enough with the addition of the chain/belt from the motor doing 2.5:1. Overall gear ratio of 15:1 would be good enough for me really.

The wheel would be fine, but the freehub or threads for the freewheel might not.

I don’t know what u mean but don’t see a need for torque going through anything but the gears.
Ill add a thread for a freewheel that will use another chain to cranks.


With just a single thin gear it could sit in a raised spot between the spokes. Two hub shell halves bolted together there or maybe could assemble the planet n carrier inside. So could use bigger gears but still use long spokes.

can use a belt between the motor and hub. It’s more appropriate for the speed it will go.



Why don’t they use thicker nylon gears in the hub motors?

 

[Chalo]

I don’t know what u mean but don’t see a need for torque going through anything but the gears.

Well it has to get to the tire somehow. The three ways bicycle hubs do that is a freehub body (which will fail if you overtorque it), a threaded freewheel (which can be stronger, but is limited by the threads the hold it), or a disc brake rotor mount (which doesn't freewheel and is designed with the physical limits of braking force as a parameter). I've stripped freewheel threads on a hub after using them to attach a big disc brake rotor, so the problem isn't only hypothetical.

As to your question about why there aren't thicker nylon gears on hub motors, they design the gears to carry the power of the motor and not a whole lot more than that. Nothing is gained by using gears that will melt from the motor overheating long before they reach their force limits. Why doesn't an economy car use the same transmission as an 18 wheel truck or a locomotive? Same reason.

 

[Hummina Shadeeba]

I was imagining the torque from the motor being transferred to the hub through a pulley connected using disk brake mount holes on the hub. the pulley would be connected to the planet carrier part. The sun gear would be stationary locked to the axle. The ring gear being the outside of the hub and the output. There’s no freehub and would be “fixed” for regen: simpler and more durable.


I’d like dual helical gears if the cost isn’t too bad: quieter
6:1 in one stage seems doable.

 

[Chalo]

I think you have more faith in a group of six crappy 5mm screws to take mega shear loads than I do.

Also, BMX hubs don't have disc brake interfaces. Hubs that do are usually too wide for a BMX frame. Hubs that can switch hit in one way or another, don't have 14mm axles.

This is resonating with the time you got me to sell you an unobtainium RH/LH threaded hub based on your guess that you could attach a large sprocket to the left side, which you couldn't.

I won't be selling you more irreplaceable things based on your wishful thinking.

 

[Hummina Shadeeba]

I think you have more faith in a group of six crappy 5mm screws to take mega shear loads than I do.

It’ll largely be speed coming off the motor passing by belt to the hub through the brake mount holes. It’s not much torque.

BMX hubs don't have disc brake interfaces. Hubs that do are usually too wide for a BMX frame. Hubs that can switch hit in one way or another, don't have 14mm axles.

The brake holes would just go on the hub to attach the driven sprocket or pulley.
I’m not looking for a hub, I’m looking to make a hub. The planetary gear takes little room along the hub and there’s room to add the threaded holes

This is resonating with the time you got me to sell you an unobtainium RH/LH threaded hub based on your guess that you could attach a large sprocket to the left side, which you couldn't.

you could attach a large sprocket on the left side. I had carriers made that have a chainring bcd and freewheel threading for the right side and in the pic above. I changed plans on that and instead of two chains used freewheeling cranks. If u want that hub back u can have it for the cost I bought it.