Anyone tried to lock the hub freewheel?

[Minikeum]

Hi guys,

kind of crazy idea here!

I’ve got a Bosch Gen 4 motor on my brand new Moustache Trail 8 Saison 10. Good fun!

I do get the rattle from the motor in descent. So I was wondering if it was possible to lock the HUB freewheel, so only the motor freewheel spins.
The drivetrain from HXR easy shift (for conventional mtb) works on that concept.

I see 3 main advantages and 2 drawbacks.

Advantages:
- Hopefully it gets rid of the rattle noise from the motor. Or at least covers it within the motor freewheel noise,
- Gets rid of one freewheel, potentially reducing the total angle of engagement,
- also the chain constantly spins (as long as the wheel turns), which means you can change gear even while coasting.

Drawbacks:
- The fact that the chain constantly spins is potentially dangerous in case of derailment, not only for the bike but also for the rider. You need to make sure the chain guard is good!
- not sure the motor is made for such use?

just trying to think out of the box. Don’t throw rocks at me please

 

[R120]

Not an Ebike but has been done on a DH bike:

Dangerholm vs. Kapfinger: The World's Finest DH Bike Challenge - Pinkbike Poll - Pinkbike

It's Dangerholm vs. Kapfinger in the quest to create the world's finest downhill bike - vote now to decide who wins a one-of-a-kind prize.

m.pinkbike.com

I would want to know what potential effect this would have on the durability of the Bosch unit though, perhaps @Bearing Man could advise?

 

[Minikeum]

Interesting, I did not know about that prototype. Only knew about HXR product
HXR also proposes small spacers to lock the ratchets of DT Swiss hubs.

For proof of concept, an alternative to completely locking the freewheel hub could be to pack it with thick grease. Thick enough that it would still be the motor freewheel doing most of the work, but in case of derailment the hub freewheel could still spin, avoiding to destroy everything and crash.

again, just thinking outside the box.

 

[Bearing Man]

Not an Ebike but has been done on a DH bike:

Dangerholm vs. Kapfinger: The World's Finest DH Bike Challenge - Pinkbike Poll - Pinkbike

It's Dangerholm vs. Kapfinger in the quest to create the world's finest downhill bike - vote now to decide who wins a one-of-a-kind prize.

m.pinkbike.com

I would want to know what potential effect this would have on the durability of the Bosch unit though, perhaps @Bearing Man could advise?

This is already an option and I have a Gen 2 here with locked freewheel for back pedal brake (mostly sold in the U.S.)
There would be no detrimental affect for the motor but you would not be able to stop pedaling, so this would probably get very annoying, especially off road.

 

[Bearing Man]

Interesting, I did not know about that prototype. Only knew about HXR product
HXR also proposes small spacers to lock the ratchets of DT Swiss hubs.

For proof of concept, an alternative to completely locking the freewheel hub could be to pack it with thick grease. Thick enough that it would still be the motor freewheel doing most of the work, but in case of derailment the hub freewheel could still spin, avoiding to destroy everything and crash.

again, just thinking outside the box.

The motor would not keep turning as the motors drive clutch bearing would disconnect.

 

[Minikeum]

The motor would not keep turning as the motors drive clutch bearing would disconnect.

Thats how I understand it. The chain and chain ring would spin, but not the motor.

EDIT: so the next question now is: would the motor clutch bearing be able to cope with this ? Or would it break, or wear quickly?

 

[GrandPaBrogan]

I do get the rattle from the motor in descent. So I was wondering if it was possible to lock the HUB freewheel, so only the motor freewheel spins.

One possible positive consequence is that you could shift gears while coasting on the flats or downhills. Pre-shifting prior to pedalling out of a corner might be handy if you started coasting into it in the wrong gear.

For proof of concept, an alternative to completely locking the freewheel hub could be to pack it with thick grease. Thick enough that it would still be the motor freewheel doing most of the work, but in case of derailment the hub freewheel could still spin, avoiding to destroy everything and crash.

Giant already beat you to this... but not in a good way. Some production batches of their 2019 hubs had thick grease which prevented the pawls engaging (dropping properly into) the drum ratchet teeth. The pawls would only engage partially and combined with 85Nm of motor torque eventually stripped the ratcheting mechanism completely - thus total hub failure.

 

[Minikeum]

Hehe I guess the grease is not such a good idea then.
thanks for the info!

 

[GrandPaBrogan]

Hehe I guess the grease is not such a good idea then.
thanks for the info!

Yes, thick grease it would seem is not a good idea... but the conundrum can usher creative thinking, which could lead to a solution in some other way.

 

[Mikerb]

All of which assumes the "rattle" is caused by the freehub. I have a Whyte 180RS with Bosch Gen 4. I do not get a rattle and neither does my wife on her Cube Access with that motor. I think the rattle may be due to rear suspension design and how that impacts together with the derailleur in use to snatch the chain when freewheeling. My wife's bike is a hardtail, and my bike has the Fox X2 Factory..........so no rear triangle movement, or well controlled rear triangle movement avoids the rattle????