Fixed gear hub for mid drive system

minde28383

10 kW
Joined
Apr 2, 2010
Messages
700
Good day,
does anybody tried to use bicycle fixed gear hub for mid drive system?
If yes, what power you pushed through it (un)successfully? What brand of hub did you use? Hub in pic is just random fixed gear (sealed bearing) hub from internet.

BTW, FYI:
Fixed gear hub which has fixed sprocket threaded with lock ring. It has threads on both sides for hub, - 34mm for sprocket and 29mm for lock ring/nut. Some of these hubs have 34mm&29mm threads on both sides, so you can screw on one side sprocket, and on another disk rotor (via 34mm adapter to 6 bolts). So the question is if these hubs do work for mid drive systems.

If you would ask why fixed gear hub instead regular rear hub... - because fixed hub has lock ring which does not allow unscrew sprocket when motor is cogging (when you don't use freewheel or one way bearing).
Sure there are two sides / two side flanged bicycles 6 bolts (each side has option to screw disk rotor or sprocket via 34mm adapter) hubs which are perfect for mid drive appliacation but these fixed gear hubs are accesable too.

You could point to a topic where somebody is experimented with fixed gear hubs on mid drive system.
 
that's what i found, see pic. Worth to consider if cogging might unscrew lock nut.
 

Attachments

  • aware.JPG
    aware.JPG
    26.7 KB · Views: 1,374
I think the answers I got in my thread asking a very similar question will help you a bunch.

To answer your question though, any heavy cogging or reverse pedaling can/will loosen the fixed gear lockring and cause issues.
 
I was truly expecting that fixed rear gear hub is a good option to use in mid drive system.
Denzel is using 34mm crew rear hub with rear free wheel (probably some expensive freewheel) on the rear hub. Theirs setup is 3000w setup. More power and these freewheels brakes. Am I correct? I saw some expensive 34mm freewheels and these might cope with more power but these cheap (15usd) brakes quick?
 

Attachments

  • freewheel.JPG
    freewheel.JPG
    64.1 KB · Views: 1,544
chas58 said:
What are you trying to do?

There are no motors that accept lock rings.

Why in the world would you NOT want to COAST with a motor?

Not many motors can accommodate a single cog.

not sure what you mean. Might be you misinterpreteted some of my text.
It might be that there are no motors that accept lock rings. Who needs them anyways?

If you mean it's good to have free wheel in direct drive system than I agree, it's good if you are not interested in regenerative braking. Some prefer one or other way but I prefer freewheel due costing and no cogging. But not installing free wheel has its own benefits - less parts which may brake, also regen option.

You said ''Not many motors can accommodate a single cog.'' What do you mean? They can and it's what?
 
Maybe I'm missing something.

Fixed gear means that you can not coast. The hub turns, the pedal turns. Pedal backwards, the hub turns backwards.
Single speed means you only have one gear, but you can coast - that is what a freewheel does.

There are no motors that use a fixed gear locking ring (i.e. lock ring that is reversed threaded from the cog).

Why do you want a lock ring? They are not needed for a single speed, as there is no way to apply torque to back of the freewheel. You can apply torque to back of a fixed gear cog, and they require a lock ring.

regenerative braking - that is done by coasting and using the drag of the motor to brake, no?

Most single speed frames are 120mm width, and there are no motors sold that specifically fit a 120mm dropout for a single speed, although I have modified some.
 
Back
Top