New motor: Made in Canada, 2022 Mid-drive system

[Gionnirocket]

I put my money in. Bafang is dead with canbus. Biktrix is offering a solid way forward. It's also fun and exciting to be involved in new technologies.
Now, three logistics questions:
1) Walk me through how the PAS will be attached/connected to the 1st batch of XDs.
2) How much custom programming will I be able to do? How will it work?
3) Can the XD eventually accommodate a IGH?

Good to see someone stepping up.
Ohhh, but wait.... A new member with a total of two posts... Where have I seen this before?

 

[JimK067]

Gion, you're not as smart as you think. I've been reading EBR since June 2000.
Penny, you are so negative I hope I never meet you.
Scrambler, thanks for the real world info. The challenge sounds fun.

 

[JimK067]

Correction: June 2020

 

[Deacon Blues]

How much different it is than riding a torque sensing rear hub? I can appreciate that higher power would be exhilarating but not really sure it comes from anything but that?

I'd like to know the answer too.
I'm not knocking this new motor (I give Briktrix a big thumbs up for going through the design, build, and testing process to bring this motor to mass production) I'm just curious as to its advantages over a rear hub motor.
I know it will be more powerful, but what else?

 

[scrambler]

I am not and expert on Hub vs mid drive, but this is a mid drive, so it has the same advantages as any other mid drive over a rear hub drive.

The fact it has dual drivetrain, simply allows it to alleviate the strain on the pedaling gear system (derailleur or IGH), as the motor power does not go through them.

It also makes it more tolerant to what gear you are on. With a dual drive train, it you stop in a middle of a hill in the highest gear (smallest cog), you can start going just as easily, as once you put power on the pedal (when PAS available, yes) or throttle, maximum power can go through the motor drivetrain to get you going regardless of what gear you are on. You can slowly pedal up a hill with full assist if you like, and do not necessarily need to pedal faster.
The gear are there for you to choose your pedaling / exercise comfort level, but do not affect your ability to power the bike through any terrain.

It is hard to fully understand all the benefits and extra fun of that system, until you have had a chance to ride one.
And yes, in my mind, the full pleasure comes if you have a great Torque/cadence based Pedal assist with it!!

 

[Gionnirocket]

Gion, you're not as smart as you think. I've been reading EBR since June 2000.
Penny, you are so negative I hope I never meet you.
Scrambler, thanks for the real world info. The challenge sounds fun.

I'm not pretending to know anything more than what I have said. I'm glad that you put your money down as I think everyone is looking forward to hearing about the experience.
But the fact is that when things don't go as planned for this bunch, a group suddenly appear and often with either no online reputation on this site... or one that consist only of cheerleading.
Now to trace your IP and see from where it emenates

 

[pennybags]

I am not and expert on Hub vs mid drive, but this is a mid drive, so it has the same advantages as any other mid drive over a rear hub drive.

The fact it has dual drivetrain, simply allows it to alleviate the strain on the pedaling gear system (derailleur or IGH), as the motor power does not go through them.

It also makes it more tolerant to what gear you are on. With a dual drive train, it you stop in a middle of a hill in the highest gear (smallest cog), you can start going just as easily, as once you put power on the pedal (when PAS available, yes) or throttle, maximum power can go through the motor drivetrain to get you going regardless of what gear you are on. You can slowly pedal up a hill with full assist if you like, and do not necessarily need to pedal faster.
The gear are there for you to choose your pedaling / exercise comfort level, but do not affect your ability to power the bike through any terrain.

It is hard to fully understand all the benefits and extra fun of that system, until you have had a chance to ride one.

I will take your word for it.

And yes, in my mind, the full pleasure comes if you have a great Torque/cadence based Pedal assist with it!!

Exactly my point.

I am not trying to be negative - but we need to highlight that PAS is make or break with this system. It is not a trivial exercise and Biktrix shouldn't hide behind that.

I'd like to know the answer too.

I know it will be more powerful, but what else?

I would like to know this as well. What is the use case this solves that other motors dont do with fewer issues, simpler components, and parts that don't need custom frame / work.

 

[m@Robertson]

This PAS will not be possible. They dont have it yet and it is in "development" with option to do it at a later date. In short it is not happening. here's why .....A true "torque sensor" requires the sensor to be on component that experiences the torque - so rear axle or the bottom bracket. Neither are possible right now with the current design without significant mods.

You are making assumptions and presenting them as absolutes. In some part those assumptions contradict the posts from the seller. @scrambler did an excellent collection of the PAS discussion as he obviously saw the same thing I did: Biktrix has said they have been using PAS on this motor for some time. They just haven't put it up for sale yet. Now... I agree a PAS-less motor is not something I have any interest in whatsoever, but I see a LOT of riders who just love their stupid throttle and never pedal. They exist, and in bigger numbers than I think any cycling-oriented rider (myself included) cares to acknowledge.

As for the quoted portion above, I don't think you have described the hardware accurately within the context of what Biktrix has said about it. They didn't say it was a torque-based system. They said it was torque+cadence. Thats very unusual, but its been done before and this is how it is meant to work:

From a standing start, the rider stomps on the crankarms. This is the normal startup on a normal bike (emtb in particular) and it creates strong torque forces. Using a bottom-bracket torque sensor (independent of the drivetrain) the controller senses this and puts out power to the drivetrain. For a predetermined - but short - period of time, the system relies on that torque sensing. This period is usually the startup of the bike leading to its crankarms achieving a cruising rpm. Once the cruising rpm is reached, its cadence sensing from there.

This is how the Cyc X1 torque+cadence PAS system is described to work (mine doesn't have this as I went to a specialty controller out of the gate on my gen1 drive).

Projecting forward to a system that does not use a traditional BB torque sensor - because it has no traditional BB - its easy to see how you could build in something that uses initial torque like this. But it won't be anything off the shelf.

@Deafcat I also wouldn't be all that interested in a motor that doesn't have a settings interface like I can use for my various BBSHDs. What you can do to a BBSHD to tame it and make cadence sensing PAS truly an extension of the rider's legs... well, the M620 is dead to me since Bafang has shut off any ability to fix their garbage programming. Nothing personal but your goals as a manufacturer are not necessarily aligned with mine. I don't even want the same thing from the same motor installed on different bikes. Assuming the motor can be had as a motor+sensors+display kind of kit (sans bike), I also have to be able to dig into its software and tailor it.

I'm guessing the reality here is that supply for these motors will be so constrained that they'll never be available for individual sale. Especially if Biktrix can sell out of them when attached to complete $6k bicycles.

 

[Deacon Blues]

Let's say I have two motors. One is a hub motor and the other is the new Briktrix motor and both put out 1200W (I know the new motor puts out more but for an apples to apples comparison let's say they both produce the same power).
What advantage does the Briktrix motor have over the hub motor?
I'm not including pedalling here, just the power from the motor.
Would the mid-mounted motor offer a more rounded/usable torque curve compared to a hub motor?
On a commuter styled ebike would one motor be better than the other?

 

[Ken M]

Would the mid-mounted motor offer a more rounded/usable torque curve compared to a hub motor?

If the torque produced at stall for both was close and the performance curve vs speed was similar you would likely not be able to tell the apart performance wise. I some riding conditions you may feel the weight of a hub motor in the rear (a legit advantage of a mid drive is the weight distribution and lower unsprung weight if a rear suspension bike). One of the advantages of the mid-drive system is that they have a lot of internal gear reduction so the stator RPMs are higher sooner - motors need to spin faster than a bike wheel but a direct drive hub motor does OK given the speed of the magnets but will not be as efficient as a mid-drive until say at a speed of 15mph+. Geared hub motors tried to address this by having upwards of a 6:1 internal reduction.

 

[TomD]

As someone else noted, rear hub motors add unsprung weight to the wheel so they don't work so well with rear suspension. Also the weight in the wheel adds affects rotational mass which I believe increases inertia, but other than that I'm not sure it would be all that different than a rear hub with the equivalent power.

 

[ruffruff]

Being a simple pragmatic thinker....
Lets try this.

I pre-order the bike knowing full well it will ship without PAS, but the promise that I can put it on later.
OK, it's later.

How much do I pay for the PAS setup?
Do I have to install it myself?
What happens when I run into a glitch and need help?
How will the warranty work? Will I void any other warranties when I short out the computer when I F it up?
Biktrix will say they will stand behind it...what exactly does that mean?

I really don't care if you buy one or not, whether it will work or not...it just isn't for me.....i can screw up a wet dream and I'm not paying $6k for a bike that I have to add a $1k(just a guess) system with my own labor and or money to take it into a shop if and when someone else has to fix it.

 

[Gionnirocket]

Being a simple pragmatic thinker....
Lets try this.

I pre-order the bike knowing full well it will ship without PAS, but the promise that I can put it on later.
OK, it's later.

How much do I pay for the PAS setup?
Do I have to install it myself?
What happens when I run into a glitch and need help?
How will the warranty work? Will I void any other warranties when I short out the computer when I F it up?
Biktrix will say they will stand behind it...what exactly does that mean?

I really don't care if you buy one or not, whether it will work or not...it just isn't for me.....i can screw up a wet dream and I'm not paying $6k for a bike that I have to add a $1k(just a guess) system with my own labor and or money to take it into a shop if and when someone else has to fix it.

And let's not forget come this summer when the PAS isn't ready to ship that the supply chain issues now exasperated by a 4th new Covid strain and/or the Ukrainian war is already a canned reply

 

[scrambler]

I have a simple rule, I don't buy stuff that does not do what I want based on the possibility that it will in the future.
I wait for it to do what I want, and then buy.

I also don't preorder anything, and always buy released products with a minimum of actual customer reviews.


For me, no amount of early access is worth the risk of being disappointed

If you preorder on the hype, don't come crying if it disappoints...

 

[Gionnirocket]

I have a simple rule, I don't buy stuff that does not do what I want based on the possibility that it will in the future.
I wait for it to do what I want, and then buy.

I also don't preorder anything, and always buy released products with a minimum of actual customer reviews.


No amount of early access is worth the risk of being disappointed

If you preorder on the hype, don't come crying if it disappoints...

You say it a lot nicer than I do

 

[JCofMN]

Nope, it's because Sensor Systems take much longer to develop than anything else. In my professional experience, automotive/industrial grade sensors are one of the longer development cycles out there, and this is no exception. We could have put PAS in from the start but I'm not willing to cut corners or compromise on strict standards and testing (we will manufacture more PAS units than any other assembly early on, due to realities of strict testing cycles in batches etc).

Farther down the discussion chain the question was asked about the differences/advantages of your new system vs a similarly powerful hub drive. Other threads expressed the opinion that not including PAS in your first offering for this drive system was a non starter. This got me wondering why such obviously smart people would do such a thing which clearly has to do with difficulty of the problem as you state. I think a major difference between hub and coaxial dual drive designs is the complexity of implementing decent PAS. Because for a rear hub motor drive system (either direct or geared) the stimulus (torque sensor reading) response (metered power to the motor) pathway involves fewer steps I suspect getting a “perfect PAS” for the Biktrix dual drive design could take some time to fully realize, , i.e.,

For Stromer just one step: the direct electrical response (user programmable parameters e.g. time delay, ramp up slope, magnitude, etc) to actuate the hub motor with the sensor at the rear dropouts measuring the torque at the rear hub. Apparently this is a point of vulnerability in Stromers as the sensor calibration can drift during wheel removal for flat repair/other routine maintenance if great care is not taken.

For the new Zen Shakti, which according to the exploded schematic on their website uses a direct drive hub motor and a pedal crank shaft torsion strain gauge torque sensor similar to the Bafang Ultra. So there’s another step, namely the pedal drive train play from chain whip/vibration and sprag clutch freewheel lash for working out the PAS programming.

Finally for the coaxial Biktrix design there’s another set of left side drive train parameters to daisy chain into the PAS problem which I suppose depends a bit on where they end up putting the torque sensor. Complicating this because of the extra powerful motor and the acoustically snubbing characteristics of the chain tensioner @Deafcat is no doubt rightfully proud of, there’s the possibility of feedback from mechanical ringing nonlinearities which might vary unpredictably under load.

But for engineers, it’s problems like this that make life worth living.

 

[scrambler]

PAS does not really care about the mechanical situation if done properly.
This involves at least torque sensing and cadence sensing, and a Controller that is programmable to process the way signals are blended to create a motor power response.

What is usually called the torque sensor, is just a way to measure the pressure applied to the pedal, as this is the key information to be able to make the power assist proportional to the effort you put in. Sometimes it is done with a sensor that actually measures torque, sometimes it is made with a sensor that measures the tension on the chain or axle.
The cadence sensor is there to measure if the rider is pedaling, at what speed, and eventually compare that to the speed of the bike to integrate the gear level.
Other sensors are sometimes put into play like inclination sensor.

Then it is all about the programming and the options it provides.

This is key, because a single way of blending the sensors' signals is not suitable for all usage modes.
As a rough illustration, if you are pedaling at regular speed on streets or smooth trails, you need to maintain a regular level of power so the ride is smooth, and that means put more weight on the cadence sensing side of things as the torque sensor signal is too irregular for comfort.
On the opposite side, if you are riding on rough terrain, the power assist needs to be closely linked to the Torque sensor signal, so you can have immediate and intuitive change in power modulation the terrain requires.

The more programmable the controller, the more natural intuitive and comfortable the pedal assist can be.

 

[pennybags]

For Stromer just one step: the direct electrical response (user programmable parameters e.g. time delay, ramp up slope, magnitude, etc) to actuate the hub motor with the sensor at the rear dropouts measuring the torque at the rear hub. Apparently this is a point of vulnerability in Stromers as the sensor calibration can drift during wheel removal for flat repair/other routine maintenance if great care is not taken.

Dont cause FUD. Stromers have millions of miles on them. There is no extra care needed for the torque sensor to work. I mean Ravi @ Zen Ebikes actually rode stromer for the longest time without any issues.

For the new Zen Shakti, which according to the exploded schematic on their website uses a direct drive hub motor and a pedal crank shaft torsion strain gauge torque sensor similar to the Bafang Ultra. So there’s another step, namely the pedal drive train play from chain whip/vibration and sprag clutch freewheel lash for working out the PAS programming.

Using a BB (bottom bracket based) torque sensor is SOP (standard operating procedure) for most non Stromer hub drives. This is not revolutionary stuff in today's world.

I agree with @scrambler that programming the controller is crucial, assuming the sensor etc are already in place. (Note : Sensor is different from the controller having a port where the sensor can be wired in ). Doing actual PAS as an afterthought is a cause for concern.

 

[Gionnirocket]

Maybe it's just me... But how about we let the makers of this six thousand dollar high resolution torque+cadence PAS tell us how it is going to work?

 

[Ken M]

This is key, because a single way of blending the sensors' signals is not suitable for all usage modes.

I have always kind of said this. There are just a lot of variables and something as simple as a throttle provide rider direct and immediate control of the assist level. I get the idea of having the sensation of riding a bike where input effort is augmented but you can accomplish this with a throttle and pedaling.