MAC motor worth it?

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Feb 19, 2020
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Hey folks, thanks for all the knowledge on this forum. I hope you aren't all sick of these newbie posts. I've been a bit obsessed with ebikes the last few weeks and I'm just looking for a sanity check before I drop some $$$.

I am basing my build on a Surly Pugsley fat bike. I want to be able to do 20 miles with 1000 ft of elevation gain/loss with some pedaling and hopefully 30+ mph top speed. So I'm thinking at least 1500w motor and 20ah battery,

I think I want a fwd hub motor, but I'm torn between a cheap kit vs a higher quality setup. I compared the 9C, DD45, 8T MAC, and a few others in the grin trip simulator and the MAC motor seems to be the most powerful and efficient. The higher torque of a geared hub also sounds nice for a heavy fat bike (maybe 230lb total with rider) as long as I can still hit 30mph with the 8T winding. But it would be half the cost if I went the cheap route....

Cheapest option:

https://www.alibaba.com/product-detail/Smart-52V-eBike-Triangle-Battery-52V_62381064225.html

https://www.aliexpress.com/item/4000026089791.html

352 battery + 347 motor kit = $699


EM3ev:

https://em3ev.com/shop/50v-14s6p-small-triangle-pack

https://em3ev.com/shop/upgrade-mac-ebike-kit-with-47-50v-battery-option-and-black-case-controller-2000w-max/

599 battery + 537 motor kit + 136 shipping + 150 wheel build = $1,422

After all this research I'm leaning towards the cheaper setup. Thoughts?
Is it true that cheap Chinese cell batteries sometimes catch fire while charging?
Any other motors/batteries I should consider in that price range?
 
keep in mind the 30mph+ is going to take a lot of wh, and so is climbing the elevation change (more wh teh steeper it is), so if you need that speed for teh whole 20 mile trip, you may need a bigger battery.

(especially if you have not allowed for headwinds or detours, and i'd also allow extra for pack aging. if you only start with just enough capacity to do the trip under ideal conditions, then under adverse ones you won't make the whole trip. and as the pack ages you will also have less and less range (and current delivery capability at speed), and also not make the whole trip. how much you wish to allow for depends on your needs, budget, and space/weight available on your bike, but 20% extra is a good start).


the grin simulator will give you a wh estimate for a particular set of conditions with a particular system, then you can multiply that wh number by the amount of time you'll be in those conditions, and do that for each set of conditions and the distance of the trip, to figure how many wh your battery must have to complete the trip.

then divide the wh by the nominal battery voltage to get the approximate minimum ah of the battery you will need.

and remember the battery is the heart of your system. if it can't produce the power needed to run the system, the system can't do what you want. if the battery is run at it's max specs, it will have a shorter lifespan (sometimes by a lot) than if it is run at it's nominal specs. and sometimes specs by a seller, especially aliexpress/alibaba/ebay/amazon/etc, are outright lies.


keeping in mind the pedalling isn't going to give you any significant effective power at 30mph+, unless you gear the system for those higher speeds, and even so you will still only be contributing a few dozen to several dozen watts to the couple thousand watts it's likely to take to do the hills at that speed.
 
for giggles i ran the mac10t in 26" wheel (default), mtb aero(default), 220lbs (default), 52v20ah battery, 4110 40a controller, and with or without 100w human pedalling, on flat roads, it only gives about 27mph at full throttle.

the 8t gives 31mph with no pedalling, otherwise the same; 1400w battery, 1200w motor, 42wh/mile.

a 5% slope yanks that down to 28mph at 1800w from the battery, 1500w at the motor, 61wh/mile.

10% slope down to 24mph, 2000w battery, 1600w motor, 81wh/mile.

since i don't have any real data on your route, let's assume you have the worst case, of a 20 mile trip that's all uphill going to your destination (and all downhill on the way back for another 20 miles). if the battery only has to last for the 20 miles one way, then...81wh/mile times 20 miles is 81 x 20 = 1620wh. that's minimum wh to make that trip, assuming it's all exactly the same conditions the whole way there. to figure out the battery size for that, 1620wh / 52v = 32ah.

if it's only 5% slope all the way there, that's 61wh/mile times 20 miles, or 1220wh. 1220wh / 52v = 23ah.

with perfectly flat roads and no headwinds all the way there, that's 42wh/mile for 20 miles, or 840wh. 840wh / 52v = 16ah.

let's say you have a 20 mile trip with the equivalent of 5% slope over just a quarter of it. so 61wh/mile for 5 miles is 305wh. then 15 miles of 42wh/mile, which is 630wh. 935wh for this trip, or 18ah.

and so on; you'll have to use your actual trip route's info to figure out actual required battery size.

**all the numbers are rounded for easy typing and thought experimenting. ;)


oh, and let's say you have a slightly breezy day, and there's a headwind the whole trip, of just 5mph average. that makes all the numbers worse by a significant amount:

on the flats 30mph 1600w battery, 1300w motor, 52wh/mile. 1040wh 20ah

5% slope 27mph 2000w battery, 1600w, 71wh/mile. 1420wh 28ah

10% slope 22mph, 2000w battery, 1600w motor, 88wh/mile. 1760wh 34ah

and so on.


if it was a really bad day, and you had a 10mph headwind....

on the flats 28mph 1800w battery, 1500w motor, 61wh/mile. 1220wh 24ah

5% slope 25mph 2000w battery, 1600w, 79wh/mile. 1580wh 31ah

10% slope 20mph, 2000w battery, 1600w motor, 97wh/mile. 1940wh 38ah


the battery and motor power doesn't go above 2000/1600 simply because of the 40a controller current limit. if you use a different controller that does allow that, the power numbers will be even worse, though you may be able to maintain a better speed...but the motor will overheat faster, and it will be harder on the battery, and the battery capacity must be higher.

btw, i didn't read the overheating time / final temperature notations, but i saw a red (motor has overheated) number in at least some of the above scenarios. that would be a worse problem than running out of battery as it can permanently damage a motor if it's hot enough.



after i ran the above numbers, i then remmebered you were talking about a fatbike, so i changed it to 29" wheels (yours might end up bigger or smaller depending on actual tires / etc), and to the guesstimate you give of 230lbs total weight. that gives, with just 5mph headwind, again still all full throttle:

on the flats 31mph 1800w battery, 1500w motor, 57wh/mile. 1140wh 22ah

5% slope 27mph 2000w battery, 1600w, 72wh/mile. 1440wh 28ah

10% slope 21mph, 2000w battery, 1600w motor, 92wh/mile. 1840wh 36ah

no headwind, on the flats 33mph 1600w battery, 1300w motor, 47wh/mile. 940wh 18ah

and so on.
 
Thanks for the reply. I should clarify I don't need or expect to go 30mph constantly, I'm happy to ride efficiently most of the time. And my commute is actually 15 miles round trip I rounded up to 20 miles for some cushion.

I think the 8T MAC and 20ah EM3ev battery are as much performance as I'm willing to spend at this point so it will have to be enough, I guess my key question is how much less performance/reliability would I see by spending half as much on a lower quality kit from alibaba. I've heard mixed things ranging from them being an incredible value for the price to potential to burn your house down.
 
Do not do front hub motor with that kind of power, its just not wise. Go rear hub motor, freewheel to match your shifters, you wont be using many speeds, probably 3 or 4. Hill climbing 11T, cruising fast largest gear ~34T and maybe one or two in between. Buy a spare throttle, they are cheap and invaluable. Thorn proof tubes, with Schwalbe Marathon Plus tires. Dont forget torque arms.

Once you ride around on an ebike, you cant get the grin off your face. Its so much fun! Steep hills are nothing.
 
Reasonable_Echidna said:
I guess my key question is how much less performance/reliability would I see by spending half as much on a lower quality kit from alibaba. I've heard mixed things ranging from them being an incredible value for the price to potential to burn your house down.
that's about right.

ali* stuff, like ebay, amazon, taobao, etc., is a crapshoot. as i noted above, the specs provided for stuff there may even be outright lies, so you can't know until you get it and use it how well it works (if it works at all). most of the time i expect that people get what they pay for. sometimes a great deal is had, and sometimes they get ripped off. luck of the draw with places like that.

known trusted vendors like em3ev are fairly certain to actually send you what you order, and to deliver on any specs they provide, as well as be able to realistically answer presales questions, *and* provide customer service afterwards if you need it. that's all part of why the prices are higher for similar items at such vendors; the cheaper places have less or none of the latter, and no real warranty either, no matter what their pages say.


if it helps, i have an old em3ev battery i got used from an es member almost 7 years ago, and it's probably at least a couple years older than that, and it still works (less capacity than original, which is normal). never had to test their customer service, but i read about good experiences with them on the forum whenever people do have to (generally you can find these by searching for posts with em3ev in them).

you can find a lot of posts discussing stuff from alibaba or aliexpress sellers, searching on those names, and there's likely to be more negatives than positives (though i have never specifically counted them).


the controllers are not likely to be all that different, but the batteries certainly will be, and the wheel build quality is very likely to be.
 
markz said:
Do not do front hub motor with that kind of power, its just not wise.
why? there's no reason to worry about it, with good torque arms and mounting.

my 2wd crazybike2, among others, used 2kw+ on the front wheel, with various crappy forks and any trouble i had along the way was poor mounting and torque arms; once those were fixed it wasn't an issue, even with hard regen braking.
 
Reasonable_Echidna said:
Thanks for the reply. I should clarify I don't need or expect to go 30mph constantly, I'm happy to ride efficiently most of the time. And my commute is actually 15 miles round trip I rounded up to 20 miles for some cushion.

I think the 8T MAC and 20ah EM3ev battery are as much performance as I'm willing to spend at this point so it will have to be enough, I guess my key question is how much less performance/reliability would I see by spending half as much on a lower quality kit from alibaba. I've heard mixed things ranging from them being an incredible value for the price to potential to burn your house down.

The cheap battery is made with generic Chinese cells ("Grade A 18650 cells" is code for that, since they can charge a lot more if they were made with Samsung, Panasonic, Sanyo cells, so they'd list it). I'd go with the EM3EV battery.

The cheap motor kit has an underpowered KT controller for your needs, if it's the one pictured (less than 700 watts continuous, and less than 1600 watts max; 700 watts is a little short for getting you to 30mph). It's sinewave, so that's cool, but it may heat up if you're running over the continuous rating. $75 on a bigger KT controller would solve that, and you'd be able to use the kit display.

Up to you which kit you go with, but don't take a chance on the battery.
 
For what you want, I'd suggest a faster wind, rear, direct drive motor. Why? Because if you want 30 now, you will want more later. The DD hub could go faster on more voltage without melting as quick as any geared hub.

Front might be a good choice, simply because you might have a front fork the same width as the typical bike. Meaning you can buy a rear motor, and it fits the front of fat bikes.

Best advice? DONT even want to go 30 mph on a fat bike. If you want fast, you need a fast tire. Fat bike tire designed to go about 20 mph, and typically 5 mph. Only want a few psi in fat bikes anyway, you can't go 30 mph with squishy tires, they will cook themselves in no time at all, unless you over inflate them, which isn't so smart anyway. What good is a fat bike with a hard tire?

So just get the geared motor, but settle for 25 mph tops, using the 10t. It will climb, and take off from stops better than the 8t, and 25 mph is more than plenty on a fat bike. Anything under 300 pounds total weight, and it will last forever in normal use. So your weight is not an issue. All you need is 1000w, and 52v, on the 10t. Keep an eye on the tires, if they feel hot, you are going too fast for them.

Later on, get a good MTB, and make it go 40 mph. With a rear DD motor. But right now, just settle for a nice 25 mph fat bike.
 
I agree , no fat bike for faster speeds,

For what you want to get a Plus Size wheel bike or a Regular F.S. Mountain bike that can accept up to 2.35 inch wide tires.
and for climbing , yes the slowest speed rear DD hub
or ...
Better yet the CYC X1 pro X2 pro, or GNG 2019 Cyclone 3000 watt mid drive.
or Big or Small Block Drive from Lighting Rod's .
 
MAC 10T for the win for sure.
40A controller and rear drive. 100% great combo have built more than a dozen
 
KarlJ said:
MAC 10T for the win for sure.
40A controller and rear drive. 100% great combo have built more than a dozen

I actually found a big difference between 36V 26A and 36V 35A, that extra kick in juice power helps out tremendously, especially on hills.
 
Again, sane fat tire e bike, perhaps 27 mph top speed out the door, but ride it 20 mph, then mac 10 t for the win. But don't feed it 2000w. Maybe 1500w, but in my climate at least, in summer 2000w would be very likely to melt it, climbing a long hill in 40c 100f temps. You can get away with a lot more of course, in Alberta Canada. I'm more conservative, and recommend what works in the worst climate on earth. He might live there too.

But he wants fast, which is going to mean a 2-2.5 inch tire, and a cheap ass dd motor can do the 40 mph club on 72v, 3000w.
 
Reasonable_Echidna....I am a BIG MAC fan.

You just have to use them appropriately because they can't reject the heat like a Direct Drive motor. Used appropriately, they are great. The MAC planetary reduction gives you a higher magnet speed and that means better efficiency and more power...all others things being equal.

IMO there are three options...

A. A 10T MAC...because it has more torque per amp than an 8T and with a 52v battery and a Schwalbe 27.5x2.8 Super Moto-X tire, it will run 28 mph on flat ground without pedaling. 52v battery because you will actually feel the better throttle response as opposed to a lower voltage even if running the exact same controller and the Schwalbe tire because it is the highest load rated tire that is ECE-R75 certified for 50 kph/31 mph that I have been able to find plus it wears pretty good too.

B. The DD45 Direct Drive motor that Grin Tech offers and a 52v battery. Not quite as much torque below 20 mph as the MAC but a solid Direct Drive Motor. The std winding will do 31 mph on flat ground. The Fst winding will go faster but you'll have less range the faster you go plus less torque per amp when climbing a hill.

C. The Grin Tech GMAC...same as "A." above but with regen capability so you can extend your range.

IMO you should buy from Grin just because they provide awesome support to the ebike community but I do like EM3ev for batteries since that is their specialty :D . Just FYI, Grin provides this forum and both the Motor/Trip Simulators.

All of the posters above make valid points...as others have recommended, run the motors, wheels, batteries, and controllers you like through the Grin Tech Trip Simulator and then you can make a decision based on some good data as opposed to what we recommend :D .
 
amberwolf said:
markz said:
Do not do front hub motor with that kind of power, its just not wise.
why? there's no reason to worry about it, with good torque arms and mounting.

my 2wd crazybike2, among others, used 2kw+ on the front wheel, with various crappy forks and any trouble i had along the way was poor mounting and torque arms; once those were fixed it wasn't an issue, even with hard regen braking.

A Surly Pugsley has a pretty normal length wheelbase. Depending on the rider’s height, battery location, and motor output torque, there could be a lot of front wheel slip (especially when climbing). My front Leaf 6T motor with 35A controller in a 29er MTB with a rear rack battery spins the wheel from a stop almost every time I use full throttle. I have learned that powered front wheel slip is relatively controllable, because the wheel still tends to pull in the direction it’s pointing.

I’m guessing your crazybike 2 had more weight on the front wheel than a normally proportioned bike, and less pronounced weight shift on acceleration due to its recumbent layout.

I agree with dogman dan that 30mph on 4” fat tires is a bad idea. If you use 65mm wide rims like the Pugsley was designed for, you can use a tire like the 26 x 2.5” Maxxis Hookworm, which measures about 3” wide on that size rim and is a good choice for higher speeds. But you can go faster with less wattage and less weight and less expense by using a more conventional mountain bike.

Note that the Pugsley uses a 135mm rear wheel that is offset 17.5mm to one side. You aren’t going to find ready-to-roll fatbike rear hub motor wheels like that. So that’s a good reason to consider using a front hub motor wheel. However, a Pugsley offset 135mm front fork will have the very same problem. There are two other kinds of non-offset Pugsley forks, but I don’t know whether they were original equipment on any Pugsley bikes.
 
Reasonable_Echidna...your battery comment...ANY battery can catch on fire if you over charge enough including the ancient lead acid :D .

The 18650 based batteries from a reputable supplier like EM3ev are fairly safe...as long as you don't over charge them. Just use a good charger that does not exceed 4.2 volts per cell and shuts off automatically. The Satiator from Grin Tech is the best charger BUT it is a little pricey :wink: .

LiPos on the other hand are much more prone to problems...especially if you over charge them or damage them.

If you are just starting out, I'd go with an 18650 based battery and I'd recommend a 14s/52v as opposed to a 13s/48v. For the same number of "p" (parallel) cells, you'll have more capacity and the 52v battery will also give you better throttle response. Adjust the number of "p" cells in the battery you buy to get the capacity you want and can afford. Just FYI, a 14s6p battery is 14 cells in series which gives you 58.8v hot off the charger and the 6p means you have 6 parallel strings of batteries (with 14 cells in each string). So a total of 14x6 = 84 18650 batteries in the pack.

I personally run a 26x4.8" Maxxis FBR on the rear of my bike now...BUT I wouldn't pair it with a MAC because the increased rolling resistance will tend to overheat the MAC in the long run. If you really want to run a fat tire (4.0 or wider) and go 30+ mph, your best option is a Direct Drive Hub Motor like the DD45 or equivalent. Drop the requirements down to about 28 mph and a 2.8" tire and a 10T MAC or a BBSHD will work. You don't have to run a fat tire on the Pugsley...I ran a Schwalbe 27.5x2.8" Super Moto-X as well as a 29x3.00 Maxxis DHR II on my Mongoose Hitch for a while but I did have to lace up different rims.
 
amberwolf said:
for giggles i ran the mac10t in 26" wheel (default), mtb aero(default), 220lbs (default), 52v20ah battery, 4110 40a controller, and with or without 100w human pedalling, on flat roads, it only gives about 27mph at full throttle.

the 8t gives 31mph with no pedalling, otherwise the same; 1400w battery, 1200w motor, 42wh/mile.
...
btw, i didn't read the overheating time / final temperature notations, but i saw a red (motor has overheated) number in at least some of the above scenarios. that would be a worse problem than running out of battery as it can permanently damage a motor if it's hot enough.

I may have not gotten the parameters exactly the same, but for me, that second configuration with the 8T overheats in less than 14 miles on the 5% grade.

For me, 30 mph is an electric motorcycle. It has nothing to do with pedaling, you can pedal as hard as you can and it won't make a noticeable difference. Your stopping power, suspension, rubber etc. has to be motorcycle grade.
 
Balmorhea said:
I agree with dogman dan that 30mph on 4” fat tires is a bad idea. If you use 65mm wide rims like the Pugsley was designed for, you can use a tire like the 26 x 2.5” Maxxis Hookworm, which measures about 3” wide on that size rim and is a good choice for higher speeds. But you can go faster with less wattage and less weight and less expense by using a more conventional mountain bike.

What if the user went with motorcycle rims and tires for 30mph on 4" tires ?
Balmorhea, your not a fan because of the heavy weight it adds (compared to bicycle rims and tires) but its an option to obtain 30mph on 4" tires that is rightfully said to be a bad idea. Lots of 4" tires available in motorcycle tires then there are for moped 2-3". I found a few options for 2.25 and 2.50" available at your local motorcycle store. Online there is TreadlandTV (television) for moped sizes, 2/2.25/2.50/2.75/3.00.

I'd look at the terrain you are riding. Fat tires are great for the fluffy/compact/crusty snow, mud, sand, rocky riverbanks and you might get better traction aired down on ice then a normal mtb size tire or +tire.
 
Simplest, easiest, cheapest, and safest way to go 31 mph on an ebike may be to take an 8T MAC and run it in a 27.5" wheel with a Schwalbe 27.5x2.8" Super Moto-X tire which is ECE-R75 certified for 31 mph, and run a 48v battery. That will give you 31.3 mph at 0% incline and you can climb a 1.4% steady state without overheating. 1.4% is actually what I use when doing runs with the simulator because it matches the real world temperatures I get when riding. Below is the Grin Tech Motor Simulator run I did to get the data :D . Just FYI, the ECE-R75 certification is for bike tires what speed ratings are for motorcycle tires.

Picture1.png
 
You can do a side by side comparison for various parameters for the same motor or different motor.

Very useful tool.


Default setting paramaters, NOT MAC
sxs.jpg






sxs1.jpg
 
I just installed a Mac 8T cassette version with 700c wheel from Eunorau, and yikes it is fast - actually hit 36 mph with a tail wind on my test ride (haven't attempted that again). Acceleration is choppy starting out, but from what I've read that's common with more basic controllers - mine is an unbranded, apparently 9x 4110 infineon/clone. Motor cable is side-exit with the L1019 connector, which facilitates a future upgrade to the Base/Phaserunner. I'm holding out for the promised bluetooth accessory to run a phone-based dash.

The part I didn't expect - there's significant drag when unpowered. I think this is actually a clutch-less (or borked) MAC! The possibility occurred to me when I started pedaling with the rear wheel up and noticed that my inline power meter turned on (battery was switched off, and there's no independent power supply) and started reporting voltage. Poor man's GMAC?
 
colsaunders2 said:
I just installed a Mac 8T cassette version with 700c wheel from Eunorau, and yikes it is fast - actually hit 36 mph with a tail wind on my test ride (haven't attempted that again). Acceleration is choppy starting out, but from what I've read that's common with more basic controllers - mine is an unbranded, apparently 9x 4110 infineon/clone. Motor cable is side-exit with the L1019 connector, which facilitates a future upgrade to the Base/Phaserunner. I'm holding out for the promised bluetooth accessory to run a phone-based dash.

The part I didn't expect - there's significant drag when unpowered. I think this is actually a clutch-less (or borked) MAC! The possibility occurred to me when I started pedaling with the rear wheel up and noticed that my inline power meter turned on (battery was switched off, and there's no independent power supply) and started reporting voltage. Poor man's GMAC?

Hmmmmm, I asked EM3ev not long ago if a side exit (wiring) rear MAC was available and they said no. EM3ev is pretty tight with the MAC factory...they were once co-located :wink: . Only version I know about that is a rear motor and has a side exit is the GMAC. Based on the drag you mentioned, I wonder if you have a GMAC, GMAC clone, or at least GMAC internals????? My 12T MAC has no drag whatsoever when the power is off. MAC does offer a solid plate that can be used to replace the clutch...i.e. create your own GMAC. Just bought one from EM3ev but haven't installed it yet so not 100% sure it fits correctly :lol: .
 
Hand turn your motor forward, then back. If it feels the same both ways your clutch is not working, or you don't have one.
 
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