Advice for a good torque hub motor

[geeksville]

Hi ya'll,

A few months ago I helped out a fair amount contributing code to Casainho's cool open-source bike project (mostly the GUI and SW102). That's my sleazy way of hoping I can spend a bit of that software karma and ask some noob ebike hardware questions .

My current ebike is a semi-custom recumbent based on the TSDZ2. But my wife has blessed selling our old tandem and replacing it with this ugly/strange thing. I would then ebikemotize it.

Because of the independent pedaling system that we want to keep from our old tandem, I can't use a mid mounted motor. But I do have some fairly good sized hills near our house. Anyone have a recommendation on a good hub motor for this application?

* about 1000W tops, preferably the ability to use a cassette. I bet 500W would be fine, 250W would not be.
* If center of mass wasn't an issue for climbing/traction I would have preferred to put it in the front wheel, but because of so much weight being at the back of the bike (me), I think it will have to be a rear mounted hub (26" wheel).
* max speed isn't too important - if it stops helping even at 20mph that would be fine. Ideally drag from the motor when just pedaling would be minimal.

Random webpages I've googled imply a Bafang CST 500W fits the bill? But I have no idea if that is the best choice.

Any advice from you people that know about bikes would be appreciated

Thanks much!

 

[amberwolf]

The MAC, or the GMAC version from Grin Tech (which doesnt' freewheel so it can be used for regen braking, but will have higher drag when not powered than a DD hubmotor), is probably the highest torque for size and power that I know of.

You can check them (and others) out on the http://ebikes.ca/simulator . If you havent used it before, then first read the entire page so you know what everything is and how to use it.


OT, but since you bring up coding/OSFW, I have a project in mind that may be useful to others regarding an addon to make the Cycle Analyst v3 able to do pure torque control from startup, among other things...but I don't know how to code (not this kind of stuff, and it's been decades since BASIC on the Apple ][ and Vic20 and assembly / hex on the 680x MCUs)....

 

[geeksville]

Thank you very much! That website looks awesome. I will play around with it and report back.

re: cycle analyst
No idea - I've never looked into "cycle analyst" but I will investigate.

 

[amberwolf]

re: cycle analyst
No idea - I've never looked into "cycle analyst" but I will investigate.

To keep the OT in this thread minimal for you, I have a thread that has ideas I wanted to implement in hardware (would still like to but in software as much as possible), over here, and I'll reply there.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=92973&p=1556213#p1362521

Unrelated to that, but also a CA-related project that would need a coder with display / GUI experience:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=104795

 

[geeksville]

Another question for ya'll:

I had been thinking I would need to use a hub motor because the IPS pedals my wife likes our our tandem would preclude using a mid-drive motor. But I just went out and looked at my TSDZ-2 based ebike and noticed that that motor will nicely let the 'captain' (if in a tandem config) stop pedaling and the chain can still keep spinning around the pedals (because of the motor clutch). So I wouldn't need to use the fancy IPS mechanism there.

Are the Bafang mid-drive motors the same way? If so, I could just use a mid-drive and have better hill climbing that allows. Plausible? (I think the TSDZ2 - though I love it is too small for this application)

 

[markz]

Another question for ya'll:

I had been thinking
Ut Ohhhhhh

I would need to use a hub motor because the IPS pedals my wife likes our our tandem would preclude using a mid-drive motor. But I just went out and looked at my TSDZ-2 based ebike and noticed that that motor will nicely let the 'captain' (if in a tandem config) stop pedaling and the chain can still keep spinning around the pedals (because of the motor clutch). So I wouldn't need to use the fancy IPS mechanism there.

Are the Bafang mid-drive motors the same way? If so, I could just use a mid-drive and have better hill climbing that allows. Plausible? (I think the TSDZ2 - though I love it is too small for this application)

 

[geeksville]

Ut Ohhhhhh

?