Finding a 120 mm DD / regen braking capable rear hub motor

[Voron]

Hello

I'm kind of stuck with an ebike frame and no clean options for rear drive hub motors. The frame has 120 mm dropouts and that eliminates practically all hubs I've seen online. I've heard that the Q hubs can be adapted to 120 mm but they're also geared hubs which lack any regen capability from the factory. The main reason for this is that the frame previously relied on internal rear wheel hub braking and lacks any proper mounting hardware for external brakes and I would want a hub that can at least somewhat slow the bike in addition to the front hydraulic brakes.

Are there any viable stock DD options that can fit into 120 mm or am I only left with machining shafts or modifying geared hubs?

Thank you

 

[Apartunis]

Leaf Bike makes 1000W/1500W/2000W rated rear hubs spaced 110mm. Keyword search "BMX" on their site.

48V 52V 1000W rear BMX bike motor

Convert your 20 inch original BMX bike to be ebike with leaf 48V 52V 1000W rear BMX bike motor.

www.leafbike.com

With tabbed washers inside the dropouts those would be nominally 118mm spacing.

What kind of bike is it?

 

[Voron]

Leaf Bike makes 1000W/1500W/2000W rated rear hubs spaced 110mm. Keyword search "BMX" on their site.

That motor is interesting but I'd rather try to stay close to the legal limit of 250w

What kind of bike is it?

It’s a 36V system with a 9A rated (18A max) Lishui controller. Originally a front hub motor setup, but I'm switching to a rear hub as part of a general upgrade/repair

 

[Apartunis]

It’s a 36V system with a 9A rated (18A max) Lishui controller. Originally a front hub motor setup, but I'm switching to a rear hub as part of a general upgrade/repair

View attachment 387914

If you keep the same controller, the bike will have the same power. Motors do not have a fixed power output. They only have rpm per volt and torque per amp. The controller dictates power.

However a 1000W rated motor will weigh considerably more than what you had before.

Consider using a geared motor but disabling the one way clutch or replacing it with a bonded or press fitted plain sleeve.

 

[Voron]

However a 1000W rated motor will weigh considerably more than what you had before.

The Swedish authorities define it as the effect that the motor can sustain for an indefinite/long time without overheating. Which is why I'd rather stay close to that specification.

Welding the clutch of a geared motor seems to lead to early gear failure but I suppose that's a price to pay. Although I'd prefer having a DD.