Help decide between All-Axle and GMAC

General Discussion about electric bicycles.
TDB   100 W

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Re: Help decide between All-Axle and GMAC

Post by TDB » Jun 06 2021 8:16pm

It sounded like you were whining about price and advocating cheap out of a warehouse by a faceless and unaccountable seller in China vs a bricks and mortar store that provides technical and warranty support and accountability and actually employs people at first world wages that has a flow on through the local economy. You think that should be free. And ready stock levels in country, which costs. Considering what you get, 20-25% I see on China hub motors for example is competitive.

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Re: Help decide between All-Axle and GMAC

Post by irf23 » Jun 06 2021 9:50pm

spinningmagnets wrote:
Jun 05 2021 9:06pm
But also less torque at the same current
The question is, does it make enough torque to make the OP happy on his particular commute. You can just as well say that the higher turn-count makes less top-speed at the same current...
Not sure how I can determine this easily. Experience?

TDB wrote:
Jun 06 2021 3:55am
irf23 wrote:
Jun 05 2021 8:29pm

Makes sense. Thanks. I would consider the 8T over the 10T for sure.
I'd select 8T GMAC at 36V you selected. It'll better low end torque than DD. It is good to have a motor a little faster than what you'd have at rated voltage. Wheel RPM is proportional to voltage. You want about 25% margin to maintain pace near the end of the trip and pack voltage is dropping to around 30V. 10T with 48V.
I suggest phaserunner set something like 20A battery current limit and 70A phase current limit. Baserunner was mentioned somewhere, but isn't rated for the higher phase current requirements of that motor.

Many here disregard the law, that's fine, but I'll just say it anyway. You have a generous 32kph and 500W legal limit in BC. From your stated desire for 32kph limit I assume you want to keep it close to legal. At least to avoid ticketing and perhaps protect insurance. 16A at rated voltage is about your legal power limit. I'd set the controller current limit at 20A and power limit at 580W for when the battery is below rated. That is based on Grin Motor Simulator model. 500W will give you about 24kph on 7% at 100kg total mass with a (reasonably fit, but not racer) human input of about 150W.
Unfortunately CA is not smart enough for rpm based power limits that could allow 500W to the road at most speeds. Fatter torque curve of the GMAC is advantageous.
If you are trying to protect insurance it is a good idea to add a simple PAS sensor (it is required) to your shopping list and set absolute speed and power limits in the controller, not CA. It will give law and insurers less against you especially if it becomes a disability compensation fight where you could be left with nothing.

https://ebikes.ca/tools/simulator.html? ... &temp_b=34

Also ignore the maximum temperature in the Grin motor simulator (redline is too high anyway) and use the trip simulator instead. It'll give you a better idea of real world temperatures. You can use a Cycle Analyst and/or Phaserunner for power roll back at something more reasonable like 90-100C and 100-110C cut off. Lower is better for motor longevity.
Thanks for this wealth of information!

spinningmagnets wrote:
Jun 06 2021 7:31am
All of the options discussed will work fine for the commute you described. I'd recommend 48V over 36V for several reasons. If you use a modest amount of power, the higher volts will mean that you use fewer amps, and the heat from amps are the issue of concern over the years. In a power outage, the 48V battery can run a small inverter, the 36V cannot.

You can cap the top speed with the cycleanalyst if you fear you might go too fast when you are not paying attention. The lower resistance of the 8T over the 10T is worthwhile, and I suspect that the only place anyone would feel a difference is if you use max throttle with the two of them side-by-side in a race. By that I mean, a poster suggested the 10T would have more torque at the same current. Would you use max current with either choice?
TDB wrote:
Jun 06 2021 7:47am
The difference between temperature models for 36V and 48V set ups being discussed are negligble... A couple of degrees across the speed range at a given power level.
I assume Grin has modelled their products accurately.

https://ebikes.ca/tools/simulator.html? ... bopen=true

I think 48V does have better forward options.
Just to clarify, with all things being equal in ebike applications, an 8T using a 36V battery would be similar to a 10T in a 48V battery?

Tommm wrote:
Jun 06 2021 9:27am
a, Weather resistance is fine in these ones, at least for the motor and controller. Their hailong is the same type of battery the grin has, if one is weather resistant the other one will be too.
Quality is also fine, I have done my research before getting this motor and I haven't seen a single fail. Motor cable is a bit long but you can shorten it in an hour. You wouldn't be saving $500, you'd be saving $1000 as it includes the battery too. Look at the last pic in the listing, they ship free and also are tax free in a whole list of countries.

b, No regen. (This can be fixed by a welder in 10 minutes, possibly would need a different controller.)
I own mid drives, this geared hub, and direct drive hubs. I can tell you the advantages of having regen on a light and slow bike are miniscule. Have you pedaled a direct drive hub with the motor off? Now do you understand a geared hub will have the motor spin 5x faster, so the resistance will be way more too. If you plan on pedaling or using PAS a lot the constant engagement of the magnets and reduction will net you comfortably in the negative range in energy consumption compared having no regen and freewheeling.

I think grin products are good (I have several) but to price an entry level spec kit to what you can get a more powerful and much longer ranged full build for, including a full suspension brand named donor bike is not something that should be encouraged. I sometimes have a laugh at their configurators and their markups.

In your place I would sell the bike in the pic and do exactly the above, for the same budget. I never understood putting $2000 worth of electronics on a bike worth $50 (mtb), the handling, capability, control, safety just won't be there. I bike with such budget should send you flying when hitting a pothole (hybrid) or get its rear rim destroyed (hardtail mtb).
I appreciate you taking the time to respond. I haven't done my research much more than looking through the link you had sent over. I understand the points you're making. I can also see your point about Grin's markup, but I also think that they do a lot for the community as a whole, and I would love to support local when I can. Maybe that means looking at other local retailers in my situation for a cheaper alternative.

I think it's important for me to consider the advice you have laid out in making my decision. I don't think it's a small chunk of change I am looking to spend. What I am taking away from your point is that donor bike matters, and I should allocate more of my budget to that rather than the higher end ebike equipment.

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Re: Help decide between All-Axle and GMAC

Post by TDB » Jun 06 2021 10:10pm

irf23 wrote:
Jun 06 2021 9:50pm
Just to clarify, with all things being equal in ebike applications, an 8T using a 36V battery would be similar to a 10T in a 48V battery?
Yes. :wink:

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Chalo   100 GW

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Re: Help decide between All-Axle and GMAC

Post by Chalo » Jun 07 2021 12:20am

irf23 wrote:
Jun 06 2021 9:50pm
I understand the points you're making. I can also see your point about Grin's markup, but I also think that they do a lot for the community as a whole, and I would love to support local when I can. Maybe that means looking at other local retailers in my situation for a cheaper alternative.
Not only are Grin's refinements worth it if you can afford them, but buying from Grin promotes needed developments and improvements that will never happen if lowest-cost overseas manufacturers hold all the cards.

Witness the flatted hub motor axle for torque transfer: a chronic serious problem presented to us by Chinese manufacturers, and so far only remedied by Grin (.ca) and Heinzmann (.de).
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: Help decide between All-Axle and GMAC

Post by MikeSSS » Jun 07 2021 10:56pm

All-Axle is a front hub, GMAC a rear. When riding pavement I can't tell the which I'm using, until there are bumps. Off road front hubs break front wheel traction more often than rear hubs break rear wheel traction.

Front hubs transmit shock up through the front forks to the handlebars, too much for me. This is with a rigid fork, it's not so bad with an old school curved and slender fork, but much worse with a very stiff fork. Heavier front hubs give worse shock than light hubs. Example my wife's Bafang G311 gives far less shock than my direct drive much heavier hub. Redshift makes a shock absorbing stem, but it's around $160 and its made for a leaning forward seating position. Suspension stems do work, I used them for hundreds of miles back in the day, they are especially great when using aero bars. Front hubs are easier to install and if you twist out the dropouts its cheaper to fix than those at the rear wheel. I've never used a front hub motor with a suspension fork, but some have.

GMAC has a great torque arm, it's a big advantage over a MAC. Rear hub motors send shock up to the seat, but rear suspension or a suspension seatpost fixes most of that. I've ridden a rear MAC on a full suspension bike and also on a rigid rear bike but using a cheap suspension seatpost and suspension fork, both were very comfortable. Offroad rear drive has less wheel slip compared to front drive.

My MAC is 12T, it will go faster than 40 kph, but 10T would be my choice for mostly 35 kph riding. The 52v, 20ah battery I'm using will easily give the range you need, at the lower speeds I ride. It's never charged above 4.15 v/cell and never discharged below 3.70 v/cell. For 30 kph road riding I'd use aero bars and cruise control, aero bars will reduce battery use and you can climb well when on them. A Cycle Analyst V3 has a great cruise control option. One ebrake lever on the aero bars would be a good idea.

The mtn bike in your photo, with front suspension fork, would be ideal for a GMAC, add a suspension seatpost, aero bars, road tires and taller gearing and you are all set. Even a cheap telescopic seatpost will work.

The Bafang G311, G310 I mentioned is a bad choice for going fast, it has 11:1 gear reduction and can throw magnets at high speed. 5:1 reduction should be fine at 35 kph.

Let us know what you decide on, if you get it and how it works out.

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Re: Help decide between All-Axle and GMAC

Post by irf23 » Jun 08 2021 4:32pm

Chalo wrote:
Jun 07 2021 12:20am
Not only are Grin's refinements worth it if you can afford them, but buying from Grin promotes needed developments and improvements that will never happen if lowest-cost overseas manufacturers hold all the cards.

Witness the flatted hub motor axle for torque transfer: a chronic serious problem presented to us by Chinese manufacturers, and so far only remedied by Grin (.ca) and Heinzmann (.de).
Well said.
MikeSSS wrote:
Jun 07 2021 10:56pm
All-Axle is a front hub, GMAC a rear. When riding pavement I can't tell the which I'm using, until there are bumps. Off road front hubs break front wheel traction more often than rear hubs break rear wheel traction.

Front hubs transmit shock up through the front forks to the handlebars, too much for me. This is with a rigid fork, it's not so bad with an old school curved and slender fork, but much worse with a very stiff fork. Heavier front hubs give worse shock than light hubs. Example my wife's Bafang G311 gives far less shock than my direct drive much heavier hub. Redshift makes a shock absorbing stem, but it's around $160 and its made for a leaning forward seating position. Suspension stems do work, I used them for hundreds of miles back in the day, they are especially great when using aero bars. Front hubs are easier to install and if you twist out the dropouts its cheaper to fix than those at the rear wheel. I've never used a front hub motor with a suspension fork, but some have.

GMAC has a great torque arm, it's a big advantage over a MAC. Rear hub motors send shock up to the seat, but rear suspension or a suspension seatpost fixes most of that. I've ridden a rear MAC on a full suspension bike and also on a rigid rear bike but using a cheap suspension seatpost and suspension fork, both were very comfortable. Offroad rear drive has less wheel slip compared to front drive.

My MAC is 12T, it will go faster than 40 kph, but 10T would be my choice for mostly 35 kph riding. The 52v, 20ah battery I'm using will easily give the range you need, at the lower speeds I ride. It's never charged above 4.15 v/cell and never discharged below 3.70 v/cell. For 30 kph road riding I'd use aero bars and cruise control, aero bars will reduce battery use and you can climb well when on them. A Cycle Analyst V3 has a great cruise control option. One ebrake lever on the aero bars would be a good idea.

The mtn bike in your photo, with front suspension fork, would be ideal for a GMAC, add a suspension seatpost, aero bars, road tires and taller gearing and you are all set. Even a cheap telescopic seatpost will work.

The Bafang G311, G310 I mentioned is a bad choice for going fast, it has 11:1 gear reduction and can throw magnets at high speed. 5:1 reduction should be fine at 35 kph.

Let us know what you decide on, if you get it and how it works out.
Thanks for this. Your mention of vibration makes perfect sense. I agree about the GMAC, but now I am questioning the cost/value commitment. I am wondering if just a simple 250W Ezee would do the trick for me, and I could save a bunch of money. This of course means making trade-offs. I'll keep you posted!

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Re: Help decide between All-Axle and GMAC

Post by JackFlorey » Jun 08 2021 4:50pm

irf23 wrote:
Jun 05 2021 10:43am
Yeah, I guess my dilemma boils down to front vs rear. I am not sure what I want. I thought I preferred the Front since it just seems easier to install and spreads the weight around. My only worry is doing 5km stretches of 7%. The reason I was thinking rear hub was because it seems to be common advice to say "If you're riding Hills = Mid-drive or Rear-Hub".
I have a slight bias towards rear hubs because they leave the front wheel lighter, and I usually use front suspensions. (Unsprung weight is bad for suspensions.) And since I ride often enough off-road, having a lighter front wheel that is easier to lift over rocks and curbs and whatnot is useful.

However, the All-Axle is pretty light, and if you aren't going with front suspension, it's a great choice.

I wouldn't worry about the 7% thing. I mean, you're not going to spin out the front wheel at 7% unless you have some pathological loading condition (i.e. both your kids on the rear rack or something.)

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Re: Help decide between All-Axle and GMAC

Post by JackFlorey » Jun 08 2021 4:55pm

Tommm wrote:
Jun 06 2021 1:47pm
I want them to be competitive and fight for it.
I don't. I want them to continue spending money on development (CA, Phaserunner, All-Axle, that stackable battery) service (the hundreds of how-to videos and the rapid turnaround on problems) and general ebike support (i.e. this website.) I greatly prefer that over them cutting costs to be more competitive with Alibaba and ditching all that stuff.

You get what you pay for, generally.

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Re: Help decide between All-Axle and GMAC

Post by neptronix » Jun 08 2021 5:03pm

I'd say 'all axle' motor all day, except it does not come in a rear motor configuration, which is the right place to have a motor on a majority of bikes.

The GMAC is a nice motor; they managed to drop 1lb off an already weight to power optimized design. Except being a geared motor, you'll never see the same efficiency on the flats.

What i really want is a rear 'all axle'... something that beats the leaf motor in every dimension would be my first pick for a motor.
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500 MTB.
Monster MTB: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: Heavy duty Cannondale semi recumbent - under construction.
Blue Dream: Maxaraya FS semi recumbent and high efficiency mid-drive - under construction.

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Re: Help decide between All-Axle and GMAC

Post by Chalo » Jun 08 2021 8:52pm

neptronix wrote:
Jun 08 2021 5:03pm
I'd say 'all axle' motor all day, except it does not come in a rear motor configuration, which is the right place to have a motor on a majority of bikes.
I wish it were true. The fact is that a wheel built on most hub motors is half a regular bike wheel, and the rear is where you need a good strong one.

I wish they'd give us wider flange spacing, but I wish they'd give us something besides flatted axle torque retention first.

Also, you'll never break the freewheel thread or freehub body out of a hub motor if it's in the front.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: Help decide between All-Axle and GMAC

Post by Mclewis1 » Jun 09 2021 9:50am

I've been watching this thread for the inevitable evolution or re assessing of requirements. I can't pretend to offer "you should do this or that" but I'll offer the example of what I've done which sounds very very similar in requirements to what you are looking at.

Right off, I'm a big fan of Grin's and I ride an RTR kit on a Surly Bridge Club as an urban all around bike (all weather, all season, groceries, commuter, 3+ hour rides for fun/conditioning). My riding is probably 75% pavement and the rest conditioned trails (fine gravel). All in me and the bike are about 120-125kgs (with or without things like bags and winter tires). I like to ride a bike, and my electrical assist is just that, assisting and not completely changing my riding experience. In my case I spent as much on the bike as the ebike kit.

The BC is a nice steel framed "trekking" style bike that can run 700c/27.5 and even big (3") 26" wheels. It has no suspension. I've set it up with 27.5" wheels and Donnelly Strava 650x50 gravel type tires (smooth tread) running about 50psi. My experience has been with road and hybrid 700c bikes. The 650x50s have been a bit of a revelation, at higher psi they roll very efficiently and their wider width handles broken pavement and softer trails with ease. The slightly softer tires (compared to the traditional 700c's) makes up for the lack of suspension. If I was going to ride rugged trails I'd be on an MTB style bike but for urban style riding I don't see the need for suspension. Anyone needed even more comfort can simply "tune" the tires by reducing the pressure in the same way serious MTB riders do. Running the larger volume tires on the street simply means you have a wider range of pressure to try out to dial in exactly what you like.

I chose a Shengyi hub motor both for lighter weight and more power than the Bafang 310. It's a regular wind, and I went with a 52v 750w battery (52 vs 36v for the occasional need for the top end speed - about 45kph). the controller is the BaseRunner which with the 52v battery is able to comfortably drive the motor with over 1000w or about 20a (for those occasional bursts of power needed in traffic of on steeper climbs). The motor with it's thermal protection (thanks to the CA) runs around 50-60C. On some nasty hills I've seen 90C. As I get back into better shape, there's less need for "bail out" throttle on the hills so I'm generally only using my top PAS setting for most of the bad ones and the temps are staying under 80C. To me this has also been a real revelation, the ability to run a slightly smaller motor for all it's benefits on 90% of my riding and with thermal protection so I don't damage it on those nasty longer steep sections.

I run both a throttle and PAS, and the PAS is setup in 5 levels (100-500w). It comes on smoothly and progressively. It's better than any other PAS setup I've ridden and gives a few torque sensors a run for their money (not necessarily better or worse, just a bit different). Most casual riding in traffic is on PAS 2 (200w), but out on the back roads I'll be in PAS 1 or often nothing at all. In the city with moderate hills and traffic I average about 8w/km and out of the open road it's about 6. This means with the 750w battery I can get over 80km (75k city) with a reserve (20%). When charging using the 80/20 rule for max battery life this works out to 65/55km of range.

The high quality Grin battery (using Panasonic 21700 cells and 40amp BMS) can be recharged at up to 8 amps (all different characteristics than the AliExpress batteries). I use a 5amp Luna Advanced charger. I normally recharge to 80 or 90% at 2 amps and often top up just before a ride at 5 amps.

The only big requirement of yours that I don't have is regeneration. Nice to have but it is what it is (currently) with medium and smaller geared hub motors. I'm looking forward to whatever Grin has been eluding to about the clutch changes in newer Shengyi motors. There's also the old school thinking about the parasitic (un powered) load on un clutched motors. The CA now has a feature that offers a small amount of current to keep the motors freewheeling when no additional power is applied. It will be interesting to see real world examples of the balance between using the feature to keep the motor "freewheeling" vs. what you get back from regeneration.

OK, I lied ifr23, i do have a specific suggestion. If I was in your position I'd put a simpler (less expensive, less powerful) Grin kit on your Trek. I feel you simply don't need the MTB in the city and the Trek will offer more versatility (racks etc.). The only things I'd change would be fitting as wide a tire as your Trek can comfortably run and put good quality brake pads on it.

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Re: Help decide between All-Axle and GMAC

Post by TDB » Jun 09 2021 9:04pm

MikeSSS wrote:
Jun 07 2021 10:56pm
The Bafang G311, G310 I mentioned is a bad choice for going fast, it has 11:1 gear reduction and can throw magnets at high speed.
Something you read? That is incomplete and misleading. These motors are happy with 26" and 32kph..

Care is needed asking more than rated 250W from them or soft pedalling 7%.

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Re: Help decide between All-Axle and GMAC

Post by irf23 » Jun 10 2021 12:05am

JackFlorey wrote:
Jun 08 2021 4:50pm
I have a slight bias towards rear hubs because they leave the front wheel lighter, and I usually use front suspensions. (Unsprung weight is bad for suspensions.) And since I ride often enough off-road, having a lighter front wheel that is easier to lift over rocks and curbs and whatnot is useful.

However, the All-Axle is pretty light, and if you aren't going with front suspension, it's a great choice.

I wouldn't worry about the 7% thing. I mean, you're not going to spin out the front wheel at 7% unless you have some pathological loading condition (i.e. both your kids on the rear rack or something.)
Makes sense. I guess I don't have a frame of reference for what will spin out and what won't.
neptronix wrote:
Jun 08 2021 5:03pm
I'd say 'all axle' motor all day, except it does not come in a rear motor configuration, which is the right place to have a motor on a majority of bikes.

The GMAC is a nice motor; they managed to drop 1lb off an already weight to power optimized design. Except being a geared motor, you'll never see the same efficiency on the flats.

What i really want is a rear 'all axle'... something that beats the leaf motor in every dimension would be my first pick for a motor.
It really is such a nice motor. Thanks.
Mclewis1 wrote:
Jun 09 2021 9:50am
I've been watching this thread for the inevitable evolution or re assessing of requirements. I can't pretend to offer "you should do this or that" but I'll offer the example of what I've done which sounds very very similar in requirements to what you are looking at.

Right off, I'm a big fan of Grin's and I ride an RTR kit on a Surly Bridge Club as an urban all around bike (all weather, all season, groceries, commuter, 3+ hour rides for fun/conditioning). My riding is probably 75% pavement and the rest conditioned trails (fine gravel). All in me and the bike are about 120-125kgs (with or without things like bags and winter tires). I like to ride a bike, and my electrical assist is just that, assisting and not completely changing my riding experience. In my case I spent as much on the bike as the ebike kit.

The BC is a nice steel framed "trekking" style bike that can run 700c/27.5 and even big (3") 26" wheels. It has no suspension. I've set it up with 27.5" wheels and Donnelly Strava 650x50 gravel type tires (smooth tread) running about 50psi. My experience has been with road and hybrid 700c bikes. The 650x50s have been a bit of a revelation, at higher psi they roll very efficiently and their wider width handles broken pavement and softer trails with ease. The slightly softer tires (compared to the traditional 700c's) makes up for the lack of suspension. If I was going to ride rugged trails I'd be on an MTB style bike but for urban style riding I don't see the need for suspension. Anyone needed even more comfort can simply "tune" the tires by reducing the pressure in the same way serious MTB riders do. Running the larger volume tires on the street simply means you have a wider range of pressure to try out to dial in exactly what you like.

I chose a Shengyi hub motor both for lighter weight and more power than the Bafang 310. It's a regular wind, and I went with a 52v 750w battery (52 vs 36v for the occasional need for the top end speed - about 45kph). the controller is the BaseRunner which with the 52v battery is able to comfortably drive the motor with over 1000w or about 20a (for those occasional bursts of power needed in traffic of on steeper climbs). The motor with it's thermal protection (thanks to the CA) runs around 50-60C. On some nasty hills I've seen 90C. As I get back into better shape, there's less need for "bail out" throttle on the hills so I'm generally only using my top PAS setting for most of the bad ones and the temps are staying under 80C. To me this has also been a real revelation, the ability to run a slightly smaller motor for all it's benefits on 90% of my riding and with thermal protection so I don't damage it on those nasty longer steep sections.

I run both a throttle and PAS, and the PAS is setup in 5 levels (100-500w). It comes on smoothly and progressively. It's better than any other PAS setup I've ridden and gives a few torque sensors a run for their money (not necessarily better or worse, just a bit different). Most casual riding in traffic is on PAS 2 (200w), but out on the back roads I'll be in PAS 1 or often nothing at all. In the city with moderate hills and traffic I average about 8w/km and out of the open road it's about 6. This means with the 750w battery I can get over 80km (75k city) with a reserve (20%). When charging using the 80/20 rule for max battery life this works out to 65/55km of range.

The high quality Grin battery (using Panasonic 21700 cells and 40amp BMS) can be recharged at up to 8 amps (all different characteristics than the AliExpress batteries). I use a 5amp Luna Advanced charger. I normally recharge to 80 or 90% at 2 amps and often top up just before a ride at 5 amps.

The only big requirement of yours that I don't have is regeneration. Nice to have but it is what it is (currently) with medium and smaller geared hub motors. I'm looking forward to whatever Grin has been eluding to about the clutch changes in newer Shengyi motors. There's also the old school thinking about the parasitic (un powered) load on un clutched motors. The CA now has a feature that offers a small amount of current to keep the motors freewheeling when no additional power is applied. It will be interesting to see real world examples of the balance between using the feature to keep the motor "freewheeling" vs. what you get back from regeneration.

OK, I lied ifr23, i do have a specific suggestion. If I was in your position I'd put a simpler (less expensive, less powerful) Grin kit on your Trek. I feel you simply don't need the MTB in the city and the Trek will offer more versatility (racks etc.). The only things I'd change would be fitting as wide a tire as your Trek can comfortably run and put good quality brake pads on it.
I really appreciate the thought you put into this post. I find it especially interesting because I think we have similar use cases. I will definitely look into what sort of tires I can put on the Hybrid. They're running on 700 x 35c tires currently.

Do you have any more info on Grin alluding to clutch changes in the newer Shengyi's?

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Re: Help decide between All-Axle and GMAC

Post by Mclewis1 » Jun 10 2021 2:54am

"Do you have any more info on Grin alluding to clutch changes in the newer Shengyi's?"

No, nothing concrete and in print. Justin has mentioned it to a few folks I've talked to, with the possibility of it coming later in 2021 ... but with all the upheavals who knows. The idea also goes back to when Grin introduced the SX motors and it's in the description.

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Re: Help decide between All-Axle and GMAC

Post by irf23 » Jun 22 2021 9:54pm

I just wanted to provide a little bit of an update. I ended up pulling the trigger on a lightly used kit (sans battery) which included:
CAV3, Phaserunner MT, CA-Log, and a V2 eZee Standard Wind Motor in 26" Rim (Not the L10 with the Thermistor and Speedsensor) with 8 speed flywheel. There are also a bunch of extra parts as well (Grin torque arms, Shimano shifters, brake rotors, speed sensor, DC converter, crankset).

The value was there for me in purchasing this kit. Due to the sunk cost, I think I will be running the Ezee motor for a bit. I am hoping to put it on my red MTB, and pick up a battery (thinking 48V 16.5Ah). From there, I think there will be a lot of work to do in terms of upgrading my donor bike (racks, fenders, new fork, saddle, disc brakes) or pick up another frame with the money i get from selling my Hybrid. From everything I have read, Ezee tends to be the best quality for smaller rear geared motors. I understand it's not the GMAC, and I did have to give up regen braking (for now), but the best part about the Grin kits is how interchangeable the parts are. I imagine I could swap out the motor and rebuild the wheel if I am finding that the Ezee just isn't cutting it.

JackFlorey   100 kW

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Re: Help decide between All-Axle and GMAC

Post by JackFlorey » Jun 22 2021 10:13pm

neptronix wrote:
Jun 08 2021 5:03pm
What i really want is a rear 'all axle'... something that beats the leaf motor in every dimension would be my first pick for a motor.
Ditto this. Maybe we could do a Kickstarter for Justin without him knowing about it until it's funded . . .

irf23   100 µW

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Re: Help decide between All-Axle and GMAC

Post by irf23 » Jun 24 2021 9:22pm

For anyone willing to chime in, any suggestions on what to look for in a donor bike. I figure with compromising on regen, hydraulic disc brakes become a must (rainy Vancouver). Would it be better to look at a better used brand? or a new big box hunk of metal?
Any input on rigid vs hardtail vs full suspension? (90% smooth pavement, 40 km/h max)

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Chalo   100 GW

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Re: Help decide between All-Axle and GMAC

Post by Chalo » Jun 24 2021 11:56pm

irf23 wrote:
Jun 24 2021 9:22pm
For anyone willing to chime in, any suggestions on what to look for in a donor bike. I figure with compromising on regen, hydraulic disc brakes become a must (rainy Vancouver).
Disc brakes and pads get wet just like rims and rim brake pads. That makes them noisy and less effective. Hydraulic actuation does the same thing as cables, but less reliably, and when it fails it fails completely. Good rim brakes with good pads work great and are easy to troubleshoot. Mechanical disc brakes like Avid BB7 do everything that hydraulics do except fail expensively in ways you can't fix at home.

Drum brakes, roller brakes, and coaster brakes are the ones that shrug off foul weather. They all have their tradeoffs, but operating in wet conditions isn't one of them.

Suspension forks and front hub motors don't get along, so if you want a front motor, use a rigid fork. You will benefit from fatter than 2" tires with or without suspension. Suspension is a must for car traffic speeds or off-road racing, but only an added source of weight, expense, and maintenance for the kind of riding you describe. I do fine with unsuspended e-bikes at up to 40 km/h, even on pockmarked and cluttered bike lanes that seem to have been ruined on purpose.

Hub motors work better the smaller the wheel, but wheels work better the bigger they are. The sweet spot for ride quality, motor performance, and component availability is probably 26". Since that's regarded as an old fashioned size at the moment, the pricing of used bikes will be relatively favorable. I imagine there are lots of nice quality 26 inch MTBs lurking in the Vancouver area that could be bought cheaply. 3x7 speed mountain bikes (the cream of the late '80s and early '90s) have the added advantage that they are compatible with threaded rear hub motors without too much fiddling around.

Whether you get a used bike or a big-box bike (and I strongly advise against the latter), you need to budget a couple hundred clams to have a shop set the bike in good running order. Old bikes will have accumulated issues, and big box bikes won't have had any competent setup at all.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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