Using a hub motor as a mid drive

[Kein Kochendes]

Hi,

I am searching for a way to effectively replace a belt reduction mid drive motor. I am thinking through the feasibility of using a high torque geared or direct drive hub motor, finding parts to mount it on a frame, and have the motor drive one chain ring, and the second chain ring drive the rear 20" wheel with a derailleur. Basically a Stoke monkey, second generation, but with 2 chains rather than 1 long one.)

I have on my Cargo bike already a freewheel crank set with 2 44t chainrings. 36v battery.

The first question I have is if it is possible to reverse the direction of a hub motor. I know DC motors can reverse direction by changing the polarity, but is it the same for a motor with a controller?

this is the motor that I am thinking of mounting. https://www.ebikekit.com/collections/wheels/products/rear-500w-heavy-duty-direct-drive-motor

Id be thankful to receive helpful advice or reasons as to why not to go this route. Attached is what I currently have, but I snap the belts constantly.

Thanks,
Kein

 

[chuyskywalker]

The first question I have is if it is possible to reverse the direction of a hub motor. I know DC motors can reverse direction by changing the polarity, but is it the same for a motor with a controller?

Yes; you can either swap two phase wires (with non-smart controllers) or programmable ones you just flip the motor direction toggle in software.

 

[Kein Kochendes]

:thumb:

 

[Axman88]

I saw this design online a while back, which uses a hub motor midway between crank and rear axle. Seems like one would need a one way clutch in there someplace. Is this similar to what you are describing?

https://evnerds.com/wp-content/uploads/2017/08/cruiser-ebikes_mis.jpg

This setup is one of several used by Ludovik ebikes, which was located in Kiev Ukraine. Not sure if they are currently active.

 

[Kein Kochendes]

Yes, close to that. Except the motor would drive the 1 chainring, and the 2nd chainring on the crankset would drive the wheel. From what I think, the motor would have to go in reverse, and the direction of the freewheel on the motor would need to be opposite to the common BMX freewheel.

 

[spinningmagnets]

There's a thread here on ES with several examples. There's also an article on electricbike dot com

https://endless-sphere.com/forums/viewtopic.php?f=6&t=38553

 

[Bullfrog]

Why don't you just install a Bafang BBSHD motor?

A Leaf DD motor is another option.

A MAC geared hub motor is a third option.

If you need a mid drive so you can change the gearing the Bafang BBSHD would be much simpler. If you ride at speeds of 28 mph or slower, I'd go with a MAC 12T or 10T motor...or a GMAC from Grin Tech. If you want speeds above 30 mph, use a DD motor. Everything I am mentioning would be rear wheel drive.

You can use a DD motor or a Geared Hub Motor as a mid drive but why go through all the headaches if there are much simpler options?