Grin Magic Drive

[lnanek]

I definitely don't want coaster braking, reverse pedaling beyond positioning my legs at stops, nor using my legs as a torque arm to resist the motor torque. So what was shown in that Grin video was useless for me. I do kind of like the additive speed instead of additive torque business and ditching torque sensors and derailleurs. So whatever I go with will need a clutch/freewheel/torque arm added at the minimum or a second motor.

Re dual VESC, maybe you can just CANBus two separate VESC together as is often done for traction control on dual motor hub systems. Grin said they are using a Phaserunner and a super-duper harness:

Their super harness is just a headless CycleAnalyst. So whatever their super-duper harness is, it can't have board level integration with the Phaserunner. Just some shared/command signals.

 

[stancecoke]

BenjaminV said MCU struggless to handle two motors.

This shows the enormous (and mostly useless) overhead in the VESC code. Most of the threads that are running in parallel on the VESC have nothing to do with driving a BLDC motor



Every cheap Hoverboard controller can drive two motors and compute and control the setpoints for both motors from the tilt sensors in real-time with a simple STM32F103 without FPU...
Benjamin's argument with the PWM frequency is strange also. EBike controllers don't need a high PWM frequency, as the they are turning quite slowly. Commercial EBike controllers are working at 16kHz, ASI controllers even lower.
If you want to drive a drone motor, that is working at much higher speeds, you will need a higher PWM frequency of course.

 

[bananu7]

Why do you always talk about the Toyota drive train?!
In his video, Justin explains exactly, that the Magic Drive doesn't need a second motor.

The only disadvantage is, that you have to be the "torque arm" for the motor torque with your force on the pedal all the time...

Oh I'm sorry, I'm just way more interested in the mid-drives we started discussing here as well, I don't see any real appeal in non-dd hub motors personally.

And as Inanek is pointing out, with a single motor you run into very similar limitations to what you'd run into in the eCVT setup with just one motor, so I feel like it's all valid; i.e., it would work best with two motors also in hub form.

How long before we see a true test and review of the magic hub and one of these ECTV mid -drives . Seems like a bunch of hype and they haven't really built a true working model they trust not to fail.

I am pretty sure GoBao has a working bike with their drivetrain, but the "trust not to fail" kinda by necessity involves a lot of real-world testing, and that takes time. "Never buy first generation of anything" remains solid advice, but I'd feel way better buying first-gen if they actually spend considerable time and effort verifying it before they put it out. It's just been announced, after all.

 

[stancecoke]

I am pretty sure GoBao has a working bike with their drivetrain

Sure, you can find test reports on YouTube:
But as always, a lot of bla bla

 

[neptronix]

I would worry about the interface a bit.

This shows the enormous (and mostly useless) overhead in the VESC code. Most of the threads that are running in parallel on the VESC have nothing to do with driving a BLDC motor

View attachment 389982

Every cheap Hoverboard controller can drive two motors and compute and control the setpoints for both motors from the tilt sensors in real-time with a simple STM32F103 without FPU...
Benjamin's argument with the PWM frequency is strange also. EBike controllers don't need a high PWM frequency, as the they are turning quite slowly. Commercial EBike controllers are working at 16kHz, ASI controllers even lower.
If you want to drive a drone motor, that is working at much higher speeds, you will need a higher PWM frequency of course.

This a hackability over performance type design. But i think they went a little too far.

I love the high eRPM support because i can just plug it into whatever ebike motor i want and expect it to work.
For example my lightest.bike mid drive, which spins at 10k RPM internally and has something like 12 poles.

My love for geared motors at high voltages has me unfortunately rejecting anything ASI based.

 

[Papa]

MAGIC

[maj-ik] / ˈmædʒ ɪk /
noun

1. The art of producing illusions as entertainment by the use of sleight of hand, deceptive devices, etc.; legerdemain; conjuring.