Anyone have experience with the Grin all axle or GMAC motors?
- Thread starter SCIFIcrab
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You'll probably find a few around here but I'd also suggest posting on https://endless-sphere.com/forums/ There you'll find much broader and deeper experience with Grin's products.
JRA
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I have a couple thousand miles on an AllAxle that is one of their first gen models. I did a 9c build and a couple thousand on that also using Grin parts before that. Both on drop bar bikes with 45c tires, I suppose what you would call gravel bikes but I mostly used them for any road I was on and trails too.
They made me a believer in front hub bikes that I hold onto to this day although I mostly use my FS mid drive anymore. My Grin hub is being rebuilt into a new frame at this time and haven't got it finished yet but looking forward to it getting done at some point. It is a great motor I feel as it is light for a DD motor, which is my preference over geared because I like the regen feature and silent running.
I ran both with 52v batteries @ 25A with no PAS only a throttle and the cruise control feature of the CA3. As much as I like torque sensing PAS on my FS bike I really prefer no PAS on my road bikes as it allows me to have better pedal feel and gear chainging. I just set to a max watt output I want, usually 500w, and pedal away.
Front hub motors are not all that popular because people think they will handle weird and tear up your forks but that is not my experience. I even mounted my 9c in a carbon fiber fork with a good torque arm and never had any issues. No problem with unwanted wheel spin either. The two wheel drive aspect does come in handy though.
They made me a believer in front hub bikes that I hold onto to this day although I mostly use my FS mid drive anymore. My Grin hub is being rebuilt into a new frame at this time and haven't got it finished yet but looking forward to it getting done at some point. It is a great motor I feel as it is light for a DD motor, which is my preference over geared because I like the regen feature and silent running.
I ran both with 52v batteries @ 25A with no PAS only a throttle and the cruise control feature of the CA3. As much as I like torque sensing PAS on my FS bike I really prefer no PAS on my road bikes as it allows me to have better pedal feel and gear chainging. I just set to a max watt output I want, usually 500w, and pedal away.
Front hub motors are not all that popular because people think they will handle weird and tear up your forks but that is not my experience. I even mounted my 9c in a carbon fiber fork with a good torque arm and never had any issues. No problem with unwanted wheel spin either. The two wheel drive aspect does come in handy though.
My DIY buids: GMAC, BBSHD, 9C RH212 and CYC Photon
Quick Note(edited 050921): This was originally a GMAC build (posts #1-125), BBSHD content will start showing up from post #126 onward, RH212 starts at post #270, CYC Photon starts around post #284 Just starting a thread for my latest ebike project. Its going to be a 52V, Grin Technologies...
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SCIFIcrab
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I can somewhat answer my own question through the motor sim from Grim, but for those who have used it does the motor, with enough current have enough push to get you past hills you might find when out on a mountain bike trail?
Total weight? (you and the bike)
Define "large" hills (grade and distance)
Wheel size? (road bike, MTB, small -sub 26")
How much help? (human power)
Take a crack at these numbers (approximations are fine), for now assume a PhaseRunner controller, 52v battery and a GMAC (8 or 10T) motor and plug it all into the Grin Motor Simulator - https://ebikes.ca/tools/simulator.html Then vary the grade and speed to see how long you can sustain climbing in a particular configuration (noting the "overheat in" parameter).
Also remember that with a properly setup configuration you're not going to "burn out" one of these motors. They have internal temp sensors and with a control system that monitors it (like the Cycle Analyst) with really heavy use you might get to an over temp condition where the power will be rolled back to protect everything from "burn out".
Edit: never mind, you know about the simulator - your last post arrive as I was making mine ... lol
tomjasz
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Use the Grin online motor simulator. It’s very accurate. Looks like up to 5% never overheat but it can run up steeper grades for a limited time.
tomjasz
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Oops! Sorry for the repeat. Do be careful using the tool. If the simulate button hasnt a red border you did get accurate results. I’ve seen a few cases where that mistake was made.
id compare 48v to 52v. With 48 you’ll lose very little speed but perhaps have more Ah in a typical frame mount. IMO 52V are over rated. And in Hailong cases usually crap builds.
Not with the Grin batteries. Their 52v batteries using Panasonic 2170s in Hailong cases have anecdotally (various forums and Grin) been very reliable ... albeit also a bit expensive.
For me one interesting characteristic of choosing 52v in combination with a smaller hub motor for an urban commuting type of configuration has been the availability of more top speed (40-45kph). This has had a safety benefit in some traffic conditions without the penalty of carrying around a larger (and heavier) motor the rest of the time ... so going 52v saved me some unnecessary weight.
For most folks though, if you assume a similar build quality (and quality IMHO is the most important consideration) I agree the choice between 48 and 52v is basically a wash.
JRA
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"have enough push to get you past hills you might find when out on a mountain bike trail?"
As much as I like my hub motors for road use as described above I don't feel that for any serious mtb terrain that they are a good option. I do think about using a G31 geared lightish weight front hub motor though for mtb use to have a low watt/lightish weight/2 wheel drive option but I am too happy with a mid drive/torque assist system for my needs.
But from my experience with the AnyAxle I can climb seriously steep dirt road type terrain no problem using under 500w but pedaling in the proper gear ratio and not going all that fast but more so than without the assist. But my motor is pulling not pushing.
As much as I like my hub motors for road use as described above I don't feel that for any serious mtb terrain that they are a good option. I do think about using a G31 geared lightish weight front hub motor though for mtb use to have a low watt/lightish weight/2 wheel drive option but I am too happy with a mid drive/torque assist system for my needs.
But from my experience with the AnyAxle I can climb seriously steep dirt road type terrain no problem using under 500w but pedaling in the proper gear ratio and not going all that fast but more so than without the assist. But my motor is pulling not pushing.
tomjasz
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Thanks!
Which batteries are they in the simulator?
I gave up on my 53KPH BBSHD 52V. 48V was 2-3% slower. Without hydraulics, it was just too risky.
SCIFIcrab
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In general are motors under 1000w used mostly for road and gravel riding, and if I wanted to get performance offroad, would I need something larger/ with more wattage?
I know that there is no perfect system and that whatever I choose will have a trade off, but is there a good motor + controller combo for an XC style build.
Still not too sure what frame I want, but would its probably going to be a 2019 and later style hardtail bike. After putting some racks I hope to make something good for bikepacking.
I know that there is no perfect system and that whatever I choose will have a trade off, but is there a good motor + controller combo for an XC style build.
Still not too sure what frame I want, but would its probably going to be a 2019 and later style hardtail bike. After putting some racks I hope to make something good for bikepacking.
I'm not sure. The 52v battery I have is in between two in the list in terms of capacity (a13 and a 16Ah) so I use the lower of the two. I don't know what the internal resistance numbers are for those two pre defined 52v batteries . For grins and giggles I have used my battery's actual measured internal resistance (from the CA) for some of the modeling. The differences between that and the two pre defined ones were so small as to be negligent (and drowned out by inaccuracies in variables like my wattage input and the amount of wind). What isn't in the simulator are models of what happens when you put a heavier load on a particular battery
I certainly don't push my Grin 52v battery very hard, even with occasional full speed bursts in traffic and climbing steep grades (both of which are fairly rare). In my case the motor, controller and wiring are the real limitations. My battery (it's a 14s x 3p config using those Panasonic NCR21700A cells) seems to bounce back very well after being asked for 20+ amps. I have no idea how it would react to drawing 35+ amps (or sustaining 20-30 amps) ... but Grin suggests it would be fine.
The modeling with the simulator is fun but you can spend a lot of time trying to pin down all the numbers as accurately as possible and in the end the uncontrolled environmentals like wind and such seem to make a much bigger impact on an ebike's performance, so I just don't sweat the details.
It's not really an issue of max wattage, for example most popular off road setups for ebike conversions are mid drive motors that are substantially less than 1000w. High speed big wattage setups (DD hub motors in the 1.5-2kw+ range) are heavy and generally unsuitable for off road use unless built around enduro (emtb/motorcycle) style setups. If I was riding a lot of technical MTB trails I'd be looking more at torque, responsiveness, and weight distribution. If you are riding longer distances off road with loaded bags then their position and how you load them is probably even more important than where the motor is. Also important will be getting the heavy battery properly attached and down as low as possible.
From what you've described I'd simply go with a build around the popular BBSHD with custom settings (so nice smooth low speed performance) and a good quality battery. The cheapest route would be one of the online storefronts on Amazon or AliExpress. Next up (and my choice) would be from one of the well established integrators such as Luna. If money isn't a concern then one of the CYCMotor kits would also be an option.
IMHO a good quality but traditionally designed steel adventure (off road touring) type of frame is also a really good choice for this type of build. I wouldn't go cheap on components but I also wouldn't go high end on features (so no 11 or 12 speed stuff). I'd spend extra on a good brakes, and wheels built with a quality strong rear hub. Then something like mid range 9 speed chain/gearing setup (you're looking more for strength and durability when used with the mid motor over weight savings and higher end features).
JRA
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Take this as you will but on forums you will find folks that only are familiar with what they have always ridden and most are relatively new to ebikes in general themselves. But there are some around that have been using ebikes for a long time and have used both hub and mid drive systems. So you should take @mclewis1 's advice above I feel as it is pretty much my same conclusion, although I would go with a TSDZ2 to get a torque sensing PAS and skip the over 1000w part. For over 1000w use it really isn't as important and cadence sensing and a throttle are going to be fine. But that is if you even expect to pedal? Bike in the over 1000w range don't necessarily need to be and quite often aren't effective to pedal anway.
If pedaling is not as high a priority as potential power with at least some range I would suggest that you look into SurRon style bikes. Plenty of snot it seems, never ridden one however.
If pedaling is not as high a priority as potential power with at least some range I would suggest that you look into SurRon style bikes. Plenty of snot it seems, never ridden one however.
Ebiker01
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I'm also consdering this options for a commuter/full sus. build .
Might decide upon Crystalite motors UFO or other 48V models. I need the speed/torque/acceleration for situation when total weight is above 230lb .
From running the Grin simulator it seems that above 230-245lb and closer to 300lbs (ebike 60lb, rider 185lb, pannier load 30-65lb) Grin/ GMAC is not that fast and responsive.
I have a few of their products and engineerin quality is A+. I wish they would make a complete ebike .
SCIFIcrab
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That motor seems to be a good solution. What are you going to use for a controller. I wish Phaserunners were not sold out for 6 months... supply shortages such
EDIT: Have you found any where to buy their other motors? I can only find the Crystalyte H4040 UFO from Grin.
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