GMAC vs Grin All Axle vs Dual Drive Catrike

E

edben05

1 mW
Joined
Sep 3, 2023
Messages
17
Location
Quebec
Hello all,
New here, I've been building a couple of eBike with different motor in the pass, BBSHD, CYC, Grin GS62, Grin Brompton Kit etc, but ive decided to build a solar Recumbent trike. Thing is I'm new to trike and how they ride and handle, I've notice from testing it without electricity that sometimes on gravel hill the back wheel skip.

So, after some research I've come to 3 possible builds (I've eliminated the Mid-Drive + Enviolo automatic, since because of reliability of bolt on mid-drive concern compared to Grin Kit on long journey)

The 3 motors configuration would be 2 front all axle (but this is heavier and lot more expensive) The Rear GMAC 10T Or the New Rear All axle.

The Catrike Pocket weight about 34 pounds I weight 197 pounds and I'm hauling my daughter in the kid trailer. I will have a solar roof + some lightweight travel gear. I am familiar with the motor simulator, but I would like some real-world input on the best configuration for a Trike, so I don't get stuck on a hill because traction is missing out.

I always use PAS my average consumption is around 7-8wh/KM rested is added by human power. Note that all tires will be the larger Continental eContact Plus which seems to have good grip and flat defense. Mainly I will go on gravel road and cycling trail so basically gravel triking ? lol.

Thanks in advance for all your input.
Cheers
 
Hello all,
New here, I've been building a couple of eBike with different motor in the pass, BBSHD, CYC, Grin GS62, Grin Brompton Kit etc, but ive decided to build a solar Recumbent trike. Thing is I'm new to trike and how they ride and handle, I've notice from testing it without electricity that sometimes on gravel hill the back wheel skip.

So, after some research I've come to 3 possible builds (I've eliminated the Mid-Drive + Enviolo automatic, since because of reliability of bolt on mid-drive concern compared to Grin Kit on long journey)

The 3 motors configuration would be 2 front all axle (but this is heavier and lot more expensive) The Rear GMAC 10T Or the New Rear All axle.

The Catrike Pocket weight about 34 pounds I weight 197 pounds and I'm hauling my daughter in the kid trailer. I will have a solar roof + some lightweight travel gear. I am familiar with the motor simulator, but I would like some real-world input on the best configuration for a Trike, so I don't get stuck on a hill because traction is missing out.

I always use PAS my average consumption is around 7-8wh/KM rested is added by human power. Note that all tires will be the larger Continental eContact Plus which seems to have good grip and flat defense. Mainly I will go on gravel road and cycling trail so basically gravel triking ? lol.

Or do any of you have and other ideal of motor for a Trike? I'm open to suggestions.

Thanks in advance for all your input.
Cheers
 
Last edited:
nicobie said:
Are you sure you need 3 motors? Or are you doing this for traction?
Click to expand...
HI, I never mention anything about 3 motors; its Grin rear all axle vs Gmac VS 2 Front grin single side axle. But yes, the issue is I want the best traction possible.
 
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Ok, sry if it wasn't clear, i will re-phrase that: 3 possibles motors configurations, Dual front, Gmac Rear, All Axle rear. Do you have any experience with them? And possibly a BBSHD with an enviolo automatic drive I may consider if anyone tried it.
 
There's at least a couple of catrike's here with dual GAA motors on them, one of them was the one that worked with grin on developing the mounting adapters grin sells for that purpose. Should be easy builds to find using "catrike".

Plenty of people using the GMAC on diffferent bikes and trikes. I have one to put on the SB Cruiser delta trike's left rear wheel, but have to do some hefty frame modification first to fit it without modifying the motor's axle.




Some have used the older NuVinci (same internal tech) with it
some have used the enviolo itself

this one is an oem bike with another bafang middrive and enviolo

etc..
 
amberwolf said:
There's at least a couple of catrike's here with dual GAA motors on them, one of them was the one that worked with grin on developing the mounting adapters grin sells for that purpose. Should be easy builds to find using "catrike".

Plenty of people using the GMAC on diffferent bikes and trikes. I have one to put on the SB Cruiser delta trike's left rear wheel, but have to do some hefty frame modification first to fit it without modifying the motor's axle.




Some have used the older NuVinci (same internal tech) with it
some have used the enviolo itself

this one is an oem bike with another bafang middrive and enviolo

etc..
Click to expand...
Nice thanks I've just look at the mid drive project seems nice ! My trike as a standard 135 mm quick release axle so it can fit GMAC or all axle without a problem, you've work with both, if I go hub route, in your opinion, Wich seems the best for my application?
 
I have not worked with the GAA, no experience with it. You'd have to look at the threads using them for data on their usage.

The GMAC I have not worked with yet; as stated I have yet to rebuild the trike frame to install it.

Which one will be better for your application will depend on your application, and especially the power level needed for the conditions you're riding under, and the torque you need to do the work, etc. The motor and trip simulators at ebikes.ca will help you find those out, along with the data you already have, to be sure that the motor can do the work required.

The Gmac is probably notably lighter than the GAA (ebikes.ca pages for them will tell you for sure), and is likely to have a significantly higher torque for the same power input because it is a geared hubmotor vs DD. (the simulator will tell you that, too) and so it will then take a smaller controller and battery to do the same job. (or rather, less capable controller and battery, they won't necesarily be physically smaller).

If you have hills, then the less weight you add, the better.

Also the solar array, if it is expected to power the system, will be better able to do this with a lower power requirement. (and the array could then be smaller and lighter).


If you have traction problems on the rear, but not the front, do you also presently drive the front wheels, or are they just steering? If front is not driven, it's fairly likely that your conditions would cause problems there if you did drive them (since there is probalby more weight on the rear wheel than either of the fronts, especially with the trailer if it's designed and mounted correctly), and you probably need bigger (fatter) tires with more appropriate tread for the riding conditions, to improve traction.

Remember that if you have traction problems now, with only pedal power, it's not going to improve because of the motor power. You should probably fix the traction problem *first*, make sure it works in all your riding conditions, and then add the motor assist. This tire

eContact Plus: The Ultimate in Confidence and Comfort

Specifically developed for the commuting and load-carrying demands of e-bikes. This high-mileage tire features a compact tread pattern to keep rolling resistance low, boosting the range of each battery charge. Thanks to the unique tread and advancement of the Continental construction...
www.continental-tires.com www.continental-tires.com
1693891110818.png
is probalby not the best choice for gravel roads and hills--it probably works fine for paved roads and sidewalks.

These days I don't ride (if I can help it) on anything that isn't paved, so I don't have significatn experience with tire types that work on gravel, but I think you will probably need something closer to this (just a random google find of knobby tread on a continental tire)
1693891317708.png
 
edben05 said:
I've notice from testing it without electricity that sometimes on gravel hill the back wheel skip.
Click to expand...
When this happens, how do you proceed?

Do you stop and then start again, or do you spin the wheel until it grabs?

This may give you an answer about the motor you want - slow speed capable or high power. A motor that spins fast from the start seems more likely to break traction than one that can turn slowly but with enough power.

The right-of-way rules on the roads in most jurisdictions I know of include that traffic heading down hill must yield as stopping on an uphill almost always breaks traction when attempting to start again.

On my trike, I'm still working to lower the motor-to-rear-wheel ratio to handle steep hills. I haven't done much off-road yet, and certainly not anything steep.
 
offGridDownUnder said:
When this happens, how do you proceed?

Do you stop and then start again, or do you spin the wheel until it grabs?

This may give you an answer about the motor you want - slow speed capable or high power. A motor that spins fast from the start seems more likely to break traction than one that can turn slowly but with enough power.

The right-of-way rules on the roads in most jurisdictions I know of include that traffic heading down hill must yield as stopping on an uphill almost always breaks traction when attempting to start again.

On my trike, I'm still working to lower the motor-to-rear-wheel ratio to handle steep hills. I haven't done much off-road yet, and certainly not anything steep.
Click to expand...
What I do is go into low gear and push hard on those pedals, have a 20-inch wheel so I'm going for low end torque. My second trike is not bought yet (the one for my wife). I'm thinking 20 inches to.
 
amberwolf said:
I have not worked with the GAA, no experience with it. You'd have to look at the threads using them for data on their usage.

The GMAC I have not worked with yet; as stated I have yet to rebuild the trike frame to install it.

Which one will be better for your application will depend on your application, and especially the power level needed for the conditions you're riding under, and the torque you need to do the work, etc. The motor and trip simulators at ebikes.ca will help you find those out, along with the data you already have, to be sure that the motor can do the work required.

The Gmac is probably notably lighter than the GAA (ebikes.ca pages for them will tell you for sure), and is likely to have a significantly higher torque for the same power input because it is a geared hubmotor vs DD. (the simulator will tell you that, too) and so it will then take a smaller controller and battery to do the same job. (or rather, less capable controller and battery, they won't necesarily be physically smaller).

If you have hills, then the less weight you add, the better.

Also the solar array, if it is expected to power the system, will be better able to do this with a lower power requirement. (and the array could then be smaller and lighter).


If you have traction problems on the rear, but not the front, do you also presently drive the front wheels, or are they just steering? If front is not driven, it's fairly likely that your conditions would cause problems there if you did drive them (since there is probalby more weight on the rear wheel than either of the fronts, especially with the trailer if it's designed and mounted correctly), and you probably need bigger (fatter) tires with more appropriate tread for the riding conditions, to improve traction.

Remember that if you have traction problems now, with only pedal power, it's not going to improve because of the motor power. You should probably fix the traction problem *first*, make sure it works in all your riding conditions, and then add the motor assist. This tire

eContact Plus: The Ultimate in Confidence and Comfort

Specifically developed for the commuting and load-carrying demands of e-bikes. This high-mileage tire features a compact tread pattern to keep rolling resistance low, boosting the range of each battery charge. Thanks to the unique tread and advancement of the Continental construction...
www.continental-tires.com www.continental-tires.com
View attachment 339251
is probalby not the best choice for gravel roads and hills--it probably works fine for paved roads and sidewalks.

These days I don't ride (if I can help it) on anything that isn't paved, so I don't have significatn experience with tire types that work on gravel, but I think you will probably need something closer to this (just a random google find of knobby tread on a continental tire)
View attachment 339252
Click to expand...
Ok nice thanks, I really like this tire's thing is I have 3 - 20 inch's wheel so this one comes in at 26 + this would i guess be my best bet : MTB Reader . My concern with the GMAC is the Drag, since it's using gear but without a clutch, I'm afraid drag will be multiply by the gears...
 
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Yes, if you use it with no power it would have drag, when going fast enough to generate currents in it.

Depending on the controller you use, or if using hte Cycle Analyst, you can setup a "freewheeling" minimum controller output, so that it always feeds just enough current to the motor to overcome the drag. (there is some info on this on the grin site, and in at least one thread somewhere here).

If you are always using the motor at least a little bit, like with a PAS setup (cadence or torque based) then there won't be any drag unless you run out of power or have some other system failure.

The DD GAA motors will also have drag for the same reason (though no gearing), and can be countered the same way.

You could ask Grin if they offer a GMAC with a freewheeling clutch, if you must have minimal drag when no power is available.
 
amberwolf said:
Yes, if you use it with no power it would have drag, when going fast enough to generate currents in it.

Depending on the controller you use, or if using hte Cycle Analyst, you can setup a "freewheeling" minimum controller output, so that it always feeds just enough current to the motor to overcome the drag. (there is some info on this on the grin site, and in at least one thread somewhere here).

If you are always using the motor at least a little bit, like with a PAS setup (cadence or torque based) then there won't be any drag unless you run out of power or have some other system failure.

The DD GAA motors will also have drag for the same reason (though no gearing), and can be countered the same way.

You could ask Grin if they offer a GMAC with a freewheeling clutch, if you must have minimal drag when no power is available.
Click to expand...
Yes thanks, I know about the freewheeling I use it on my Brompton direct drive, it's just I thought that maybe since it's gear drag would be worst cause ont the multiplication effects of the gears
 
amberwolf said:
Yes, if you use it with no power it would have drag, when going fast enough to generate currents in it.

Depending on the controller you use, or if using hte Cycle Analyst, you can setup a "freewheeling" minimum controller output, so that it always feeds just enough current to the motor to overcome the drag. (there is some info on this on the grin site, and in at least one thread somewhere here).

If you are always using the motor at least a little bit, like with a PAS setup (cadence or torque based) then there won't be any drag unless you run out of power or have some other system failure.

The DD GAA motors will also have drag for the same reason (though no gearing), and can be countered the same way.

You could ask Grin if they offer a GMAC with a freewheeling clutch, if you must have minimal drag when no power is available.
Click to expand...
So should I got with GMAC or Grin all axle ?
 
Personally, I'd recommend a Grin all-Axle on EACH front wheel.

Here's why:

Your trike is currently rear wheel drive and you can't get sufficient traction because your center of mass is more closer to your front wheels. If you move the center of mass backward to get more rear wheel traction, you increase the risk the trike will tip over and decrease the amount of lateral G forces it can sustain without tipping.

An all-axle side motor in each front wheel adds more mass over the front axle line AND allows your trike to become AWD, with electric assist up front and pedaling driving the back wheel if you add a torque sensing PAS system. The Grin all-axle side motors also have adapters made specifically for Catrike. It's not a "cheap" solution, but your trike will be a beast because of it and will be a very satisfying vehicle to use. It will also likely be usable in the snow with this AWD.

If you can't afford to do both at once, do one motor at a time.
 
The Toecutter said:
Personally, I'd recommend a Grin all-Axle on EACH front wheel.

Here's why:

Your trike is currently rear wheel drive and you can't get sufficient traction because your center of mass is more closer to your front wheels. If you move the center of mass backward to get more rear wheel traction, you increase the risk the trike will tip over and decrease the amount of lateral G forces it can sustain without tipping.

An all-axle side motor in each front wheel adds more mass over the front axle line AND allows your trike to become AWD, with electric assist up front and pedaling driving the back wheel if you add a torque sensing PAS system. The Grin all-axle side motors also have adapters made specifically for Catrike. It's not a "cheap" solution, but your trike will be a beast because of it and will be a very satisfying vehicle to use. It will also likely be usable in the snow with this AWD.

If you can't afford to do both at once, do one motor at a time.
Click to expand...
Ok I like that so dual motor increased stability and traction at the same time! Could I do it with dual baserunner? I have 2 V6 baserunner and cycle analysist lying around its would make it cheaper to reused them on this build instead of buying 4 new controller etc
 
edben05 said:
Ok I like that so dual motor increased stability and traction at the same time! Could I do it with dual baserunner? I have 2 V6 baserunner and cycle analysist lying around its would make it cheaper to reused them on this build instead of buying 4 new controller etc
Click to expand...
I'm fairly certain you can. You may want to ask ebikes.ca for support, but there is a part you will need to make this work. See the following shunt:

Dual Controller Shunt

Make sure that the Baserunners can work with the Grin All-Axle's connectors. If they are not currently compatible, ask Grin if they have an adapter to allow your controllers to work with them or if they can make you one.

Doing this successfully will allow you to ride it in the snow without losing traction, although you might need studded tires, and if the snow is deeper than the amount of ground clearance you have then you can cancel the idea altogether.
 
Last edited:
The Toecutter said:
I'm fairly certain you can. You may want to ask ebikes.ca for support, but there is a part you will need to make this work. See the following shunt:

Dual Controller Shunt

Make sure that the Baserunners can work with the Grin All-Axle's connectors. If they are not currently compatible, ask Grin if they have an adapter to allow your controllers to work with them or if they can make you one.

Doing this successfully will allow you to ride it in the snow without losing traction, although you might need studded tires, and if the snow is deeper than the amount of ground clearance you have then you can cancel the idea altogether.
Click to expand...
They have just confirm that baserunners can do it without issues. So is dual for the price realy worth it vs the BBSHD+ Enviolo hub combo? Utha Trike in they email told me that mid drive makes more sens on a Trike, it got me confuse since on bikes its doesn't really matter exept if your running low current and doing MTB.
 
edben05 said:
They have just confirm that baserunners can do it without issues. So is dual for the price realy worth it vs the BBSHD+ Enviolo hub combo? Utha Trike in they email told me that mid drive makes more sens on a Trike, it got me confuse since on bikes its doesn't really matter exept if your running low current and doing MTB.
Click to expand...
Middrives can often be more hassle and wear and tear on your components(such as your chain). If you want to eliminate cogging torque losses so that you can pedal with the motor disabled and nothing plugged in, and your battery is so dead you can't cancel out the cogging losses with your controller, middrives make a lot of sense. Middrives, for the power output, are also much lighter than a hub.

But it is not easy to design a system to make a middrive trike have AWD. What Grin is offering is almost a bolt-on solution that will allow cornering performance and traction that no off-the-shelf middrive could give you due to enabling AWD.

Using hub motors, you're going to need torque arms and torque plates, so that you don't damage your frame.

You could have twin all-axle hubmotors up front, AND have a middrive in the rear as well, and both systems would compliment each other nicely. With a hub motor in the rear, you would have to make sure the kV ratings and wheel size gave you as close to the same RPM per volt as possible, but a middrive mostly bypasses that issue altogether and you can select a gear ratio that works best.

Tradeoffs are what they are.

My personal preference is hubmotors. They're easier to install and generally less hassle, maintenance, and tinkering overall to keep everything operational. Unfortunately, hub motors on the market have not at all kept pace with the technology available, while middrives have.
 
Having dual front wheel hub motors is a great setup but…it’s also expensive as the all-axle costs like $600 per hub, and you have to run a separate controller for each wheel.

I think the GMAC is good in that for a recumbent where you really want power is in moving from a stop and in going uphill. I don’t think that optimal top speed is that important for recumbents which is where direct drives are better than geared hub. I think lower speed applications are more needed.

Another thing to consider is the strength of the recumbent frame. The weight of hub motors makes me a little leery when installing them on recumbents. The frame feels flimsy due to its geometry.
 
taiwwa said:
Having dual front wheel hub motors is a great setup but…it’s also expensive as the all-axle costs like $600 per hub, and you have to run a separate controller for each wheel.

I think the GMAC is good in that for a recumbent where you really want power is in moving from a stop and in going uphill. I don’t think that optimal top speed is that important for recumbents which is where direct drives are better than geared hub. I think lower speed applications are more needed.

Another thing to consider is the strength of the recumbent frame. The weight of hub motors makes me a little leery when installing them on recumbents. The frame feels flimsy due to its geometry.
Click to expand...
After speaking with Grin i also think single GMAC would be enough an probably have a lot of torque, still i like the Grin All axle made in canada like the fact that its not from china, but i dont want performance to be affected. I realise my Cranset used a 24 mm x 68mm width bottom braket thats : FSA Gossamer Pro witch is a BB386EVO interface and I'm not familiar with this anyone knows if i can use a Erider or change it to a simple Sqare Taper to use a 24 pole cadence sensor (witch i think i prefer)
 
The Toecutter said:
My personal preference is hubmotors. They're easier to install and generally less hassle, maintenance, and tinkering overall to keep everything operational. Unfortunately, hub motors on the market have not at all kept pace with the technology available, while middrives have.
Click to expand...
👍🏽👍🏽
 
edben05 said:
After speaking with Grin i also think single GMAC would be enough an probably have a lot of torque, still i like the Grin All axle made in canada like the fact that its not from china, but i dont want performance to be affected. I realise my Cranset used a 24 mm x 68mm width bottom braket thats : FSA Gossamer Pro witch is a BB386EVO interface and I'm not familiar with this anyone knows if i can use a Erider or change it to a simple Sqare Taper to use a 24 pole cadence sensor (witch i think i prefer)
Click to expand...
With their system, you could start with one motor in the front, and later add a second as funding permits, should you desire to do so. Like a front-wheel drive car where only one wheel receives output from the engine, you're going to have torque steer out the ass with a single front motor. But you will have the trike running as an EV, and that's the most important part of performing the conversion. You can always upgrade later.

To change the bottom bracket, you're going to need a bottom bracket extraction and installation tool for each type of bottom bracket that you are working with. Park tool has excellent videos on the subject.

 
Hello so just for a small update I went with a single FH212 fast wind from grin, I've program them and waiting on my new tires for some snow testing!
I went with those sine GAll axle was out of stock and since it's the first trike me and my wife own we don't even know if we like it so in the end we decided to spend less money on them and maybe invest in the future in a next gen G all axle if we use the trike more then our regular ebikes
 
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