Removing/locking the freewheel in an internally geared hub?

A

ARod1993

100 W
Joined
Feb 24, 2014
Messages
249
Location
Cambridge, MA
I've started doing preliminary planning on a very high-powered homebrew e-MTB build that would be bordering on light motorcycle territory, and I've been looking at using an internally geared hub inside the frame as a transmission (see this thread for more details on that. While doing a bit of Googling on IGHs I realized that basically all of them have internal freewheels that make it impossible to implement regen, which in this case is a major downside. I don't want to deal with the losses and extra weight of a motorcycle or dirt bike gearbox, but I want to be able to have regen on this build; does anyone know whether it's possible to modify an IGH in a manner that would disable the freewheel without compromising its ability to shift?
 
I have welded an IGH internal freewheel so it is locked up to effectively make a geared hub into a DD hub but with an inbuilt reduction ratio. It was only a low powered one so will be fine. In a higher powered one I would have made a new centre for the clutch that engaged with the outer aswell as being splined to the shaft to lock it up.
So yes it is doable, but this was in a wheel not being used as a mid drive. As DS said above, you will also have the drive chain and sprocket mounting issues to over come for a mid drive setup. And extra bi-directional loading of the drive gears to consider.
 
Just a quick clarification: I'm not talking about using a geared hub motor like the Tongxin or BMC, I'm talking about mating an internally geared bicycle hub like the Shimano Alfine to a large RC outrunner, using it as an ebike transmission, mounting the whole assembly in a custom frame, then running a 5:1 or 10:1 output reduction via a single sprocket attached to the fixed-gear side of a flip-flop bike hub on the rear wheel. I want to be able to brake regeneratively through this setup, even though most if not all bike hubs have an internal freewheel. I know that it's possible on a derailleur drive to simply spot-weld or Loctite the freewheel to the sprocket cassette and not compromise shifting ability, and I was wondering if you can do something analogous to that on an internally geared bike hub.
 
There are other issues to consider too, the drive chains are under tension on the opposite side during regen so sprung tensioners may not be useable and any suspension design will need to be very carefully laid out regarding wheel travel arc's and sprocket centres to ensure chain tensions stay within acceptable tolerances without tensioners.
Seems a whole heap of trouble when an extra $30 of battery will give you the 10% extra capacity that all this trouble might get you.
 
ARod1993 said:
While doing a bit of Googling on IGHs I realized that basically all of them have internal freewheels that make it impossible to implement regen, which in this case is a major downside. I don't want to deal with the losses and extra weight of a motorcycle or dirt bike gearbox, but I want to be able to have regen on this build; does anyone know whether it's possible to modify an IGH in a manner that would disable the freewheel without compromising its ability to shift?
Click to expand...

I've looked at this in quite some depth for a kind of application (geared unicycles), and both the short answer is generally no. The internal mechanism relies on the internal play from it freewheeling in order to be able to shift, and the freehweeling pawls are integrated an not usually a separate piece that you can simply take out or disable. The Nuvinci CVT hub is tempting, but in that case it relies on forwards torque on the sprocket to compress the friction plates against the transmission balls. With a backwards torque and there is no compression and it simply slips, have a look at the 5th post here:
http://www.unicyclist.com/forums/showthread.php?t=89581

As mentioned in that thread, the Sturney Archer S3X is one of the few bicycle IGH's with reverse torque transmission. But it's only 3 speeds with a 160% range, and people have blown them out with aggressive pedaling, let alone high powered ebike drives. So in your case I don't think it would hold up at all:
http://www.sturmey-archer.com/products/hubs/cid/3/id/47.html

Does anyone know if the multispeed bottom bracket transmission drives like the Pinion are reverse transmitting? There is a lot more torque on the front crank than you have on the rear hub so the gears inside would be built to handle higher torque loads:
http://pinion.eu/en/discover-pinion/pinion-p1-18/
 
justin_le said:
ARod1993 said:
While doing a bit of Googling on IGHs I realized that basically all of them have internal freewheels that make it impossible to implement regen, which in this case is a major downside. I don't want to deal with the losses and extra weight of a motorcycle or dirt bike gearbox, but I want to be able to have regen on this build; does anyone know whether it's possible to modify an IGH in a manner that would disable the freewheel without compromising its ability to shift?
Click to expand...

I've looked at this in quite some depth for a kind of application (geared unicycles), and both the short answer is generally no. The internal mechanism relies on the internal play from it freewheeling in order to be able to shift, and the freehweeling pawls are integrated an not usually a separate piece that you can simply take out or disable. The Nuvinci CVT hub is tempting, but in that case it relies on forwards torque on the sprocket to compress the friction plates against the transmission balls. With a backwards torque and there is no compression and it simply slips, have a look at the 5th post here:
http://www.unicyclist.com/forums/showthread.php?t=89581

As mentioned in that thread, the Sturney Archer S3X is one of the few bicycle IGH's with reverse torque transmission. But it's only 3 speeds with a 160% range, and people have blown them out with aggressive pedaling, let alone high powered ebike drives. So in your case I don't think it would hold up at all:
http://www.sturmey-archer.com/products/hubs/cid/3/id/47.html

Does anyone know if the multispeed bottom bracket transmission drives like the Pinion are reverse transmitting? There is a lot more torque on the front crank than you have on the rear hub so the gears inside would be built to handle higher torque loads:
http://pinion.eu/en/discover-pinion/pinion-p1-18/
Click to expand...

The Pinion is utterly amazing; 18 evenly spaced gears and a total shifting ratio of 636% is better than the damn Rohloff. If that thing can handle 250N*m in from the pedals without suffering excessive wear, then 30-150N*m off an RC motor should be completely safe for it. My only concern with that (assuming it works) is cost; it's an unorthodox drivetrain solution that's nicer than a Rohloff, and if I had to guess the price point I'd be surprised if it was under 1500 to 2000 USD. The main attraction of the Shimano Nexus and Alfine lines was that I could get 8 speeds for a couple of hundred bucks and thus avoid the situation where a few expensive, hard-to-service components drive my build cost through the roof.

*Update: I just poked the Pinion people about getting a couple of their drives for prototyping purposes; we'll see when and if they get back to me*
 
I was wondering the same thing, out of curiosity. Did the years bring any new insight here?

I see a 5-Speed Sturney Archer is now on sale at Grin:
https://www.ebikes.ca/shop/electric-bicycle-parts/motors/direct-drive/igh-305.html
@justin_le, would this IGH-motor support regen?

Of course we are not talking about 600% range but smaller +/- 44%.
Besides the possibility of changing the gear, is there any advantage of an IGH over a 5:1 fixed-gear such as the MAC/GMAC?
(mechanical resistance under high temperature, heat dissipation via statorade?).

Thanks.
 
Mahe said:
I was wondering the same thing, out of curiosity. Did the years bring any new insight here?
Click to expand...

Ha ha, that is quite a few years. The TDCM IGH motor has no problem at all doing regen since it's just a conventional direct drive hub motor, the 5 speed internal gears are just for pedaling and don't play into the motor system at all.

If you wanted to use the TDCM 5 speed as part of an e-tranmission project in a way that the internal gears are used by the motor, then you'd be mounting the motor in a jack shaft arrangement spinning in reverse so that the motor RPM is coupled to the cog, and using a chain around the cog drives the bicycle wheel.

In that mid-drive scenario where the hub motor actually does make it's way through the 5 speed gearbox, there is definitely no regen.
 
ARod1993 said:
The Pinion is utterly amazing; 18 evenly spaced gears and a total shifting ratio of 636% is better than the damn Rohloff. If that thing can handle 250N*m in from the pedals without suffering excessive wear, then 30-150N*m off an RC motor should be completely safe for it.
Click to expand...

If you don't pedal, then sure. Some folks can put in 400 Nm at the cranks, which depending on the gear ratio could exceed 250 Nm even before the motor does its thing. Granted, most of those folks aren't riding e-bikes, but with motor power added on top? Lots of us could do it.
 
I think the effigear freewheel is built into one of the axles as they have a fixed rear hub: https://www.effigear.com/functioning
Kervelo I am not so sure: https://www.kervelo.com/quartz/
Kindernay claim to have a special large clutch - might be worth looking into in case it is somehow different in a useful way: https://kindernay.com/products/ or see: https://kindernay.com/wp-content/uploads/2019/06/Kindernay-XIV-fatbike-11.jpg

I can't quite figure out what you are planning, but I had often thought that one advantage of a left side drive hub gear was that a middle mount motor could drive it via the disc mount and have regen, while the cyclist retained freewheeling from driving the normal side (with a tiny current to simulate freewheeling for the motor) - maybe that helps - the hub gear itself would be unmolested in this case, with all the fab work on the motor mount.
 
You must log in or register to reply here.

Similar threads

R
    • Like
A critique of mid-drive riding recommendations (and hub drive criticisms)
Replies
15
Views
5,064
Bullfrog
B
K
Which geared hub for BBSHD in a full-fat tandem trike?
Replies
15
Views
2,056
calab
C
B
CYC X1 Pro Gearing (Off Road)
Replies
1
Views
919
spinningmagnets
spinningmagnets
amberwolf
Amberwolf's Cloudwalker Cargo Bike
Replies
20
Views
3,978
amberwolf
amberwolf
B
Locking clutch/freewheel in geared hub motor for regen?
Replies
22
Views
5,776
kylerlaird
kylerlaird
Back
Top