My new Custom GMAC build

[linklemming]

If I put it under the stem and in front of the stem, I wont be able to see it...which might not be such a bad thing

The grin bracket isnt long enough to allow side mounting from my measurements.

I could put it in under the stem and behind the stem and while it would be readable, I would probably crash trying to read it.

I could put it in a top tube bag (which would hide all the wiring....yeah) and make my own display which would get data from the serial data logging port.

I could also just keep the mainboard and get rid of the LCD board and make my own enclosure with my own display. I can setup the CA with PC so I really dont need the LCD display or buttons.

Im currently researching the top tube bag option. I can design simple PCBs and software is my profession.

 

[AHicks]

The size of that display is probably the biggest reason I haven't done a GMAC conversion yet. I REALLY hope they redesign/update that thing to more modern standards.

You haven't mentioned anything about the regen or how it's working. Is this something you just haven't gotten around to configuring yet? -Al

 

[linklemming]

The size of that display is probably the biggest reason I haven't done a GMAC conversion yet. I REALLY hope they redesign/update that thing to more modern standards.

You haven't mentioned anything about the regen or how it's working. Is this something you just haven't gotten around to configuring yet? -Al

I dont really think I have a need for regen, I actually would prefer a clutch GMAC.

I dont like the idea of having brake switches. For one I dont like having the motor cutout on brake inputs. Sometimes I prefer to tap the brakes while still pedaling instead of stopping pedaling(like exiting a corner where I was just a little to fast, or maybe a last minute line adjustment during an uphill switchback). Since a brake switch is just that (a switch), a way you could adjust the regen is using the throttle when the switch is activated. I would prefer not to add braking habits that would go outside of what I have always done. I might install a seperate momentary switch at some point and play with regen though. I would consider trying a brake system that had a proportional output so I could vary regen with lever pressure but Im not aware of any product to do this. Someone on endless sphere has done this but I dont like the implementation.

On the display, Im going to try several things. Back when I did the opensource TSDZ2 stuff, I actually put opensource software on a bafang 860C display so there is source code for that. I have also been researching opensource code for the KT-LCD7 and KT-LCD4 LCD displays.

Ordered a top tube bag today, Im going to try putting the CA in the bag and then just having a voltage display
https://www.amazon.com/VGEBY-Voltme...s=ebike+voltage+display&qid=1604548909&sr=8-4

I always use a garmin edge 25, so technically this would be all I need, we will see how this works out.

I also am going to play with this OLED display on my spare time.
https://www.sparkfun.com/products/12923

 

[linklemming]

The Surly Troll uses a horizontal dropout with what they call "gnot boost"(common to many surly frames). Basically its sized for a 12x145 thru axle. By using 145mm for the rear width, you can easily move the chainstays in/out to get regular thru axle spacing of 142mm or boost spacing of 148mm.

In addition, it supports 135mm spacing with adapter washers for Quick Release or Solid Axles. The following pic is for the solid axle washer. The larger part of the washer is 4mm thick.

The GMAC motor has solid axles obviously and is 138mm wide. If one was to use the washers as intended on both sides(wider part of washer on inside of dropout), the power wires would be damaged where they exit the hub motor. Luckily with the gnot spacing this was easy to remedy by flipping the washer on the output wire side (non drive, disc side). This yields spacing of 142mm which equals thru axle spacing.

Here is a pic of the non drive side

And the drive side

 

[linklemming]

Here are some more pics.

I like batteries that have 3 mounting points (Some only have 2 at the upper part of the battery mount with an aluminum section on the rear part of the battery, I typically drill the aluminum mount to have 3 mounting points)

The Surly Troll frame has 3 welded on water bottle mounts which fit my battery perfect (Im using a Panasonic 52V, 13.5ah panasonic battery I purchased from Luna a year ago). Note that the battery had to be slid up/forward to clear the chainring.

Here is a pic of the tire clearance using 26x2.35 smartsams on a 24 inner width rim. This frame can accomodate 26x3 tires(711mm diameter), I am hoping to go to 27.5x2.4(706mm diameter) tires in the future with the possibility of going to 27.5x2.6(716mm diameter). My goal has always been to run 27.5x2.6 tires, hopefully they will fit this frame (the only surly frame I could find anwhere at this time)

 

[linklemming]

Some more pics:

42t chainring clearance (The spider can take two chainrings and this is mounted on the inner chainring position)

A side view of the spider and chainring(surly stainless steel chainring).

 

[linklemming]

2 more pics

The torquearm mounted to the chainstays with the supplied hardware. Im not sure I will end up with this setup, I might mod the torquearm to bolt to the rear dropouts directly

And finnaly, the torques sensor wire output. I need to protect this somehow, I will likely 3d print a mount/protector.

 

[drewberz]

Thanks for all of this! So cool. I have drooled over this motor for a while. Your part selection makes a lot of sense.

How would you compare the smoothness/power delivery of the motor relative to a Yamaha, Bosch, or Brose?

 

[Deacon Blues]

Last year I test rode an ebike with the GMAC motor (HillEater). While descending a fairly steep hill I noticed that there seemed to be quite a bit of drag and I didn't need to use the brakes that much.
It wasn't until I got to the bottom of the hill that I remembered the regen braking.

 

[drewberz]

Last year I test rode an ebike with the GMAC motor (HillEater). While descending a fairly steep hill I noticed that there seemed to be quite a bit of drag and I didn't need to use the brakes that much.
It wasn't until I got to the bottom of the hill that I remembered the regen braking.

How was the sensation of it?

 

[AHicks]

I dont really think I have a need for regen, I actually would prefer a clutch GMAC.

I dont like the idea of having brake switches. For one I dont like having the motor cutout on brake inputs. Sometimes I prefer to tap the brakes while still pedaling instead of stopping pedaling(like exiting a corner where I was just a little to fast, or maybe a last minute line adjustment during an uphill switchback). Since a brake switch is just that (a switch), a way you could adjust the regen is using the throttle when the switch is activated. I would prefer not to add braking habits that would go outside of what I have always done. I might install a seperate momentary switch at some point and play with regen though. I would consider trying a brake system that had a proportional output so I could vary regen with lever pressure but Im not aware of any product to do this. Someone on endless sphere has done this but I dont like the implementation.

On the display, Im going to try several things. Back when I did the opensource TSDZ2 stuff, I actually put opensource software on a bafang 860C display so there is source code for that. I have also been researching opensource code for the KT-LCD7 and KT-LCD4 LCD displays.

Ordered a top tube bag today, Im going to try putting the CA in the bag and then just having a voltage display
https://www.amazon.com/VGEBY-Voltme...s=ebike+voltage+display&qid=1604548909&sr=8-4

I always use a garmin edge 25, so technically this would be all I need, we will see how this works out.

I also am going to play with this OLED display on my spare time.
https://www.sparkfun.com/products/12923

Back to the regen, tapping your brake would kill the motor obviously, but it would have no effect on the regen. For the regen to engage you would have to have the brake switch engaged AND be using the throttle. There's no "all available" regen on/off. It's proportinal using the throttle. Brakes on, the throttle becomes your regen control. That's stock to my understanding. There's an optional plan that uses a second throttle for the variable braking.

This in mind, not clear how tapping your brakes would affect the way you are riding now?

Too, if you are not going to use the regen feature, a standard 35a KT controller will run that hub just fine (and likely way more simply). It's all I use for my MAC 12t powered bike, which uses many of the same components the GMAC uses. A lot of people wondered about that at first (if it could switch fast enough), but it's been working great. No noise to speak of and good power available right from the start. I do have the amperage dialed back to 20a max. in the parameters out of concern for the battery I'm using. -Al

 

[Deacon Blues]

How was the sensation of it?

It just felt like the brakes were dragging a bit.

 

[JRA]

"There's no "all available" regen on/off."

That is not my experience as I have a momentary switch on my left brake hood that I can press that activates regen which I have the percentage set in my CA3. It has nothing to do with the throttle although you can set it up that way also via the CA3. It's quite handy and the first thing I reach for when looking to slow down.

 

[linklemming]

"There's no "all available" regen on/off."

That is not my experience as I have a momentary switch on my left brake hood that I can press that activates regen which I have the percentage set in my CA3. It has nothing to do with the throttle although you can set it up that way also via the CA3. It's quite handy and the first thing I reach for when looking to slow down.

Thanks for confirming that, that was my impression of how it worked, you set an amount of initial regen initiated by a switch and then can use throttle to add more (if configured that way).

I think I would like the dual throttle method, I would prefer to keep the brakes independent of motor power/regen...whatever you want to call it. I hated that feature on my Juiced CCX(which was needed to keep the bike from taking off at lights sometimes) and love not having it on this build

 

[JRA]

"I would prefer to keep the brakes independent of motor power/regen."

If you refer back to my cockpit jpeg you can see a red button on the left brake hood that is either on or off by pressing/releasing. It is completely independent of the actual brake itself but easy enough to apply both at once if needed. As I said I usually apply the regen first, I find it especially handy for keeping it alround 30 without using my brakes on downhills, but mostly just to scrub speed at any time. Really does save on pad wear.

 

[AHicks]

"There's no "all available" regen on/off."

That is not my experience as I have a momentary switch on my left brake hood that I can press that activates regen which I have the percentage set in my CA3. It has nothing to do with the throttle although you can set it up that way also via the CA3. It's quite handy and the first thing I reach for when looking to slow down.

Thanks for confirming that, that was my impression of how it worked, you set an amount of initial regen initiated by a switch and then can use throttle to add more (if configured that way).

I think I would like the dual throttle method, I would prefer to keep the brakes independent of motor power/regen...whatever you want to call it. I hated that feature on my Juiced CCX(which was needed to keep the bike from taking off at lights sometimes) and love not having it on this build

You guys are both wildly underestimating the potential regen available from the GMAC. Consider that the motor armature is turning 5 TIMES as fast as a direct drive (while both are traveling at the same speed) for starters! You would NOT want to engage this regen fully doing 15 - 20 mph for instance. If your battery could handle it, the motor is capable of up to 90 amps of stopping power. That's not something you want to turn on or off with a momentary switch. You'll very likely lock up the rear wheel immediately if just turned "on". That's why they've gone to the trouble of setting it up as a "variable" regen. All of this is set up to your tastes (and battery's ability to accept a (big) charge).

He does a demo of the braking here at 3:30 or so. This is the bike stopping without brakes, using regen only, using only 500-800 watts of regen....

He goes into a more detailed setup here, detailing the potential amount of regen available:

 

[JRA]

There is still the ability to set it for a certain % of regen. Granted it has the potential to be variable and really powerful but there is no reason to have it set that high. At least for my needs using my All-Axle 250w is plenty.

You won't use a CA3 because it's too "big" but that is what makes it work the way I use it and the possibility for the same effect using the GMac.

 

[linklemming]

You guys are both wildly underestimating the potential regen available from the GMAC. Consider that the motor armature is turning 5 TIMES as fast as a direct drive (while both are traveling at the same speed) for starters! You would NOT want to engage this regen fully doing 15 - 20 mph for instance. If your battery could handle it, the motor is capable of up to 90 amps of stopping power. That's not something you want to turn on or off with a momentary switch. You'll very likely lock up the rear wheel immediately if just turned "on". That's why they've gone to the trouble of setting it up as a "variable" regen. All of this is set up to your tastes (and battery's ability to accept a (big) charge).

I think you are also wildly underestimating my understanding of GMAC regen. I have been researching the GMAC/Phaserunner/CA for over a year and researching obsessively for the last 2 months or so while I was in between jobs. Yes I understand how the gearing makes it even stronger. I have watched every pertinent grin video multiple times. I still learn something everytime.

If there was a proportional brake lever I would likely at least try it with the GMAC. I actually 3d printed a handlebar mount for a loadcell to be used as a brake lever I had laying around (I have designed and produced load cell amplifier boards for my sim racing hobby). There was a guy on endless sphere who did one as well but it was kludgy(some sort of cable arrangement). Justin has discussed a proportional brake lever on endless sphere as well but has implied that nobody makes one.

I dont think I implied anywhere that a switch would produce max regen. Its doable, you could set it up like that but that would be just plain dangerous and stupid as you have noted.

The CA has "MANY" options on how to implement regen. If you only use a switch, you can program in a 'baseline regen', which can be anything. This is what JRA is referring to.

If you want to use your throttle and a switch then the throttle would add to the baseline regen when the switch is engaged.

In the end, I didnt buy the GMAC at all for the regen. I bought it for the better design elements like solid 10mm axle which requires no frame modifications, the integrated torquearm and the better power connector. If I could buy a clutch kit for the GMAC I would do it.

I went the CA/Phaserunner route because of all the options, there are many things I want to try. I wanted to learn the phaserunner&CA inside and out for future projects including 72Volts

 

[linklemming]

Thanks for all of this! So cool. I have drooled over this motor for a while. Your part selection makes a lot of sense.

How would you compare the smoothness/power delivery of the motor relative to a Yamaha, Bosch, or Brose?

Its very good but not on par with my Brose Bikes which I have found the most responsive and why I own 2.

The mid drives seem more responsive as well the slower you go as the gearing utilizes the torque better. The faster you go, the less you fell the mid-drive responsiveness. I can feel a difference above 20mph but its very subtle.

Still a few parameters I could play with to change the response...all in due time

 

[linklemming]

How was the sensation of it?

I have never run my GMAC without field weakening which increased its unloaded speed from 31mph to 39mph.

Its rare I can hit that speed in real life coasting down a hill , I usually dont go much higher than about 30mph but have coasted to 36mph without feeling anything

I did give it full throttle yesterday on a 3% downhill and got to 40mph before i had enough