eZee vs MAC? Your thoughts?

Both are geared hub motors for the rear wheel. The eZee 26R would be from Grin, the MAC from EM3ev. Prices are about the same, when all things are equal and including shipping. What would your choice be and why? Is there much difference between them?

Bike will be a full suspension bike with rear hub motor and Grin torque arm. I weigh 196 lb.

Riding speed will be 12 to 20 mph, average will be 12.5 to 14.5 mph. Battery will be 52v, 20Ah carried on seatpost rack or panniers on the side of that rack.

Comfortable ride is important, high speed isn't. Most climbs I do are gentle, under 6% grade, there is one 14% near my home but it's just for fun.

Bike will be used for a bucket list ride on the Moab Slickrock Trail, I expect to walk next to the bike and use throttle walk assist on the steeper climbs.

Well: eZee or MAC 12T?

The MAC is bigger. MAC stator is 22mm wide (135mm diameter).

eZee is 17mm wide stator (130mm diameter)

Both can benefit from ATF cooling, if you don't mind the occasional oil spot.

https://endless-sphere.com/forums/viewtopic.php?f=3&t=4892

Thanks to SpinningMagnets and all those who previously investigated the two hub motors in question and posted info about them. The big hub motor thread is quite a great read and study asset.

There's a lot of information in past posts and links from them. It takes time and study to make sense of all this information. I've gone through it several times and tried to form an accurate picture of what is going on.

Then there is the Grin simulator. Often people run their simulations based on full throttle climbing and flat land riding. I almost never use full throttle, especially when climbing, so that's how I ran my simulations. I also ran walk assist simulations using 30kg for the bike weight, leaving out my pushing of the bike. Battery used for sim runs was 52V, 20Ah.

For 15% grade I used 70 and 80 rpm cadence in 24 chain ring and 34 and 30 tooth cog. I used 100 watts for my power and 260 lb total weight. Resulting speed was 3.7 to 4.9 mph. Both the MAC and eZee do well for this use, overheat times range from 15 to 14 minutes at 3.7 mph. For 4.9 mph, overheat times are more like 10 to 11 min.

Walk assist was used for 20% grade with me providing 0 watts power and bike weight of 66 lb and speed of 1.5 mph. Neither motor overheats. My actual walking speed will probably be about 1 mph but the simulator doesn't like that low a speed.

30% grade was again never overheat, but the simulator allowed me to use 1.1 mph for walk assist speed.

For normal bike path simulation I used 2% grade because that seems to make the numbers come out right. For riding speed average of 12 to 14.5 mph, the numbers for both the MAC and eZee agree closely to my actual ride data and neither overheats. Human power of 75 watts gives motor power a bit more than my observed numbers and using 100 watts human power gives motor power a bit lower than my actual results. So, I'm probably pedaling at about 85 watts, I had guessed 80 watts, so the numbers are pretty close.

Anyway, sim results indicate that either the MAC or the eZee would work well for my everyday use and both would work for the Moab Slickrock Trail bucket list ride.

The posts I read indicate both the MAC and eZee are good and reliable motors. Luna says the MAC weighs 9.5 lb, Grin says the GMAC weighs 8.4 lb, same as the eZee. I'm guessing the eZee is actually a bit lighter, less unsprung weight is a good thing.

Price is pretty much the same for both. So it's Grin or EM3ev, Justin or Paul, and both have great reputations.

Wouldn't it be great to be a decisive person? Agghhhh

PS: I investigated mid drives like the BBSHD, TSDZ2 and Cyclone. The first and last look like they have serious throttle problems and the second one has all sorts of programming options, too many choices for a lazy guy like me. Mid drives sort of seem more like a hobby than transportation. Then there is the possible broken chain miles from the trailhead at Moab. Too many hobbies already and not enough time or emotional commitment for another hobby is a major problem with mid drives.

If they both meet your needs and are therefor a tie, here's a tie breaker: Spare parts availability. When you strip the gears, which one can you get easily parts for?

Both stellar vendors. But if the Mac is a slower wind, it will be better for riding slower, up the steeper bits. Not more power, nor more torque, just more efficient at the less than 15 mph riding, than a 10t mac, or similar wind in the ezee.

If the Ezee comes in slow wind, then its always a no brainer to buy on continent, these days.

You can get the battery and charger from any vendor on your shortlist. If the battery-to-controller connector is different from the kit you would like to get, the plug-and-socket is easy to swap out.

When it comes to the kit, get the motor, controller, and throttle from the same vendor.

I also recommend that you get a spare throttle and a digital multimeter (DMM). I have a $15 DMM from sparkfun, accurate enough for basic troubleshooting.

If you need to swap connectors, I'd recommend a 100W soldering iron, and 63/37 solder, even 60/40 if that's what's available. The lead-free stuff is a real headache. If you need a few pieces of heat-shrink insulation to cover a repaired wire, I recommend 3:1 marine (*for boats).

Used a 25 Amp controller for the following sims.

Ran some sims for MAC 12T and 10T. MAC 12T uses less battery than the 10T when walking the bike up a 20 or 30% grade, but both would get the job done with minimal battery use. This is pretty much a one time or perhaps a few times use at Moab, here in SA there are a few walk ups but my DD front hub did those with no problems. Both the 12 and 10 turn MACs would work for the walk up portions of Slickrock Trail. So would the 250 rpm eZee, which sims about the same as a MAC 10T, at least for my less than full throttle use.

Ran a pedaling 100 watts with electric assist, sim for 15% grade, pedaling 80 rpm in 24 front and 34 rear cog, 100 watts pedal power. The MAC 12T and 10T were very close as was the 250 rpm eZee.

Ran 13 and 16.5 mph pedaling 50, 75 and 100 watts for all three motors, results were pretty much the same.

Ran 25 mph pedaling 100 watts, the MAC 12T could only get to 21.x mph, the MAC 10T and 250 rpm eZee could do 25 and were about the same.

Looks like there is no wrong choice here, I'll probably get a 10T MAC or 250 rpm eZee.

Got a kit from Grin, Justin is a really good explainer of how things work and proper setup. Besides, they are in Vancouver, that's near Seattle and we really like hanging out in Seattle. Got to drive a steam powered launch, the Puffin, at The Center for Wooden Boats in Seattle and really like Canadian candy, like the Big Turk Bar, so might visit Grin sometime. China and Paul would be harder to visit, but you never know, Great Wall of China, Great Mall of China, transparent cliff sky walk, and all that tourist stuff.

OK, got to check into parts availability, like gear sets. Low power riding is an advantage with respect to gear life.

As I see it, the big ebike problem is the desire to learn more and build something new and different. Hmmm, perhaps that's not a problem after all.

Ride on and thanks for all the help.

Mike S

Been riding a MAC 12t converted Rad City for about a year now. Absolutely love it for it's power, low noise (even when compared to a direct drive), and it's efficiency.

I just wanted to add that I'm using a KT controller and display w/12 fet and 35a capacity, but I use it set up with a max output of 1200w. Quiet, smooth starts, and no known issues. Went this way mostly because I know the controller from some previous projects that I've had really good luck with. And they're inexpensive! Note they say it's a square wave (noisey) but in torque simulation mode, it's quiet, like a sine wave would be. I suspect that's because it IS a sine wave.

http://www.pswpower.com/ven.php?cargo.2016-3f-28ym

If you go this route, suggest you buy your accessories here at the same time for plug and play capabilities. Can save you a lot of time.

Interesting, thought the MACs were supposed to be noisy!

i've owned both.. get the mac!
ezee is not worth it for the small weight loss!

Ordered a MAC 12T cassette rear hub with 12FET controller, from EM3ev. It is a slower wind than the eZee, with wider and bit larger stator. Getting a CA3-DPS too.

Sold the ebike I've been using since 2014, it was really hard to part with it. That bike was near perfect for the riding I have been doing, but not well suited for the Moab bucket list ride I want to do. Then there are some canyons to ride in San Diego and the FS bike with slow wind MAC will be far better for those.

Thanks to all who have helped with this decision.

Now to look closely at the rear dropouts. I might make steel plates for both sides, to take the axle torque.

And, now to start saving for the next battery. I had 48v, 14Ah, the next one will be 52v, 20Ah.

Happy Trails guys and thanks again.

Best wishes,

Mike S

That's gonna be a big battery to hang on a seat post rack. Make sure you have a hell of a seat post, and a sturdy rack. Maybe do a custom job?

I had a rack rated for 20lbs with a little 36v 12ah battery on it and it snapped after a couple months. I could only imagine your battery at Moab is going to put a lot of strain on the rack and post.

I've been eyeballing this one. Looks fairly stout, but ymmv.

https://www.blackburndesign.com/p/central-seatpost-rear-bike-rack/

MAC hall replacement, many pics of the internals...

https://endless-sphere.com/forums/viewtopic.php?f=2&t=63771

Rear motor, battery hanging on the back of the seatpost... makes a wobbly front.
Balance your build with proper weight distribution. It will be a much better ride. Hint: you should be able to lift it holding the top tube 4 inch ahead of the seat tube.

I'd absolutely never use a rear rack again. Poor weight distribution, makes you more wheelie prone, induces a countersteering effect.... just no!

There's very good reasons why a motorcycle carries the majority of it's weight in it's center. Emulate that design at any opportunity you have.

Good advice, thanks.

Rear rack battery worked great on my front wheel DD ebike because of the weight of the 25 pound front wheel. Weight distribution was pretty well neutral just behind the bottom bracket. Battery was a 48v, 14Ah Shark type.

My wife had problems with the weight of her 36v, 10Ah battery on the rear rack. Her hub motor is a Bafang G311 front hub, it's small and light. We moved her battery to the bottom of a pannier mounted on the rear rack. This works a lot better for her.

My FS bike doesn't have an open triangle like a GT LTS 2 does. The battery can probably be mounted on top of the top tube, since that tube is dog legged downward in the middle. If I can find one of those GTs I'll get it if finances allow. That way the battery can be mounted in the center triangle.

Riding the motorcycle, I don't play motocross, instead I chug along in first gear, picking my way through the terrain. Riding is about looking around and seeing stuff for me, like geology, terrain, plants, trees and animals. I used to play road racer but still walk funny from those days. Moab is about stopping a lot and looking around, no high speed desired. Same thing last summer when driving Hell's Revenge, it was all about being there and marveling at the place. For this type slickrock riding the MAC 12T will probably get the job done. Back home it should do well on the creek side trails, there's not a lot of vertical ... unless you seek it out and the downhill guys certainly use the steep vertical. I'm amazed by their riding and the bikes they use.

Well as usual I am a little late to the party :lol: .

As far as your motor selection, IMO you made the correct choice as long as you plan to pedal some, walk the steep trails (like you said), and you don't hit any rocks or obstacles on the trail extremely hard.

The springs in your clutch will get knocked out of place if you hammer over obstacles...happened to me riding over roots and rocks. The failure mode I experience was my clutch would not freewheel but it still transmitted power just fine. No guarantee on the failure mode others might experience.

Why you need to pedal and walk the bike up steep hills...if you push the MAC too hard, it will over heat. Set your CA to start reducing the power at about 130C and to shut down if the motor reaches 140C...those are maximums, you may want to go a little lower. The MAC can easily handle 40A/112A battery/motor current for relatively short periods of time. I have gone well beyond that just make sure your controller and your battery are capable as well.

A smaller diameter rear tire will help a little bit...it effectively gears the motor a little lower.

Batteries...you may have already decided but I like the 14s6p pack that EM3ev sells and mounting it in the triangle bag that comes with it reduces some of the shock loading as you go over bumps...I used some of the packing that came with the battery to cut and make custom pads inside the triangle bag. The triangle bag may not be feasible with your full suspension. Somebody mentioned weight distribution and I agree 100%...attempt to get everything as low as possible and have 50/50 front/rear or as close as you can get. Your bike will handle a LOT better.

If you experience a lot of overheating with your MAC...three options:
A. Add about five ounces of distilled water and Motul MoCool (at the appropriate percentage) through one of the brake rotor bolt holes...after you open the motor and remove as much of the grease as possible.
B. Add about five ounces of low visosity ATF after removing the grease as best you can.
C. Go to a BBSHD and gear it with a 28T front and a 22T rear White Industries 72 points of engagement freewheel. Your top speed with a 52v battery will be about 19-20 mph with a 27.5x3.00 Maxxis High Roller tire. The BBSHD puts out more torque with the 28/22 gearing than the MAC and doesn't over heat as easily.

If you pedal some (I did not) and walk up the steep trails...you'll probably be fine :wink: .

If you haven't put the grease on the gears yet...buy some Mobil SHC 100 and use it instead of the grease packet that EM3ev supplies. I use just enough to cover the teeth on the ring gear. The engineers at Mobil recommended it to me. If you already have your motor together it is not worth the extra effort to remove the motor and clean out the current grease...it will work just fine.

Please don't misunderstand...I am a huge MAC fan. If used appropriately...you will enjoy it and it will last a looong time .

Battery mounting...I mounted my 14s4p battery on the bottom side of my downtube on my Diamondback Catch 1.

I mounted the slider to the two bottle bracket mounting points on the bottom of the downtube and then used two large hose clamps I bought from McMaster Carr to hold the battery against the downtube. Just don't over tighten the hose clamps or you'll crack your battery case. I used pieces of inner tube between the hose clamps and the battery case.

Grin Tech has what they call Bottle Bobs if you don't have mounts on the bottom of your downtube. They come in several different configurations.

Here is a link to the hose clamps: https://www.mcmaster.com/catalog/126/334/

Just make sure your front tire won't hit your battery when the suspension fully compresses.

spinningmagnets said:

The MAC is bigger. MAC stator is 22mm wide (135mm diameter).

eZee is 17mm wide stator (130mm diameter)

Both can benefit from ATF cooling, if you don't mind the occasional oil spot.

https://endless-sphere.com/forums/viewtopic.php?f=3&t=4892

Click to expand...

22mm MAC is bigger, which means better.

neptronix said:

i've owned both.. get the mac!
ezee is not worth it for the small weight loss!

Click to expand...

I'd take his word for it!

I'd add some Ferrofluid / Statorade
https://www.ebikes.ca/shop/electric-bicycle-parts/motor-hardware/cooling-mods/statorade.html

This is a good guide on the MAC motor, with measurements of the physicality. Might as well copy it here for prosperity reasons.
https://electricbike.com/forum/forum/knowledge-base/motors-and-kits/new-channel/55334-asi-mac-motor-documentation-and-purchase-guide

You might be able to find those large stainless steel clamps at your local auto parts stores. That's where I found mine. Placing the battery on the bottom of the down tubes vs on the top where the water bottle would go is a sound idea. It would lower the weight distribution.

The MAC, controller, etc. came in. Now I'm planning the torque arm or arms. The Grin rear torque arm I bought probably won't work.

The battery has not come in yet, so mounting it is a future project. It's a 14s, 6p battery. Perhaps it will fit on the underside of the downtube, I hope so.

Grin Tech Rev 4 Rear Torque Arm works great on my MAC.

Bought the MAC motor and the torque arms from EM3ev and I used two torque arms...required removing the six pin plug temporarily to install the arm on the left side.

After running it a couple years...IMO one torque arm would be sufficient and I run 40A/112A (battery/phase) current to my 12T MAC.

The Grin Tech torque arms are a little pricey but they work great.

Battery installation....what shape is your battery? Using two hose clamps worked great for my rectangular shaped battery when mounting it on the bottom side of the down tube. I used pieces of inner tube between the hose clamps and the battery and between the hose clamps and the frame...just to give it a little cushion. Be careful not to over tighten the hose clamps...you can crack the plastic battery case and/or dent the frame tubing if you really crank down on them.

Just in case I haven't mentioned it, the MAC will produce more torque per amp than any motor currently available which means better acceleration than any motor available :wink: ...that is why I am a huge MAC fan.

For a 14s6p battery, I don't think you can accelerate any faster than with a 12T MAC . If you go to a 72v battery and a high amperage controller, you can get higher acceleration but your overall weight is going to be much higher as well.

Did I mention I am a huge MAC fan :lol: .

Bullfrog said:

Just in case I haven't mentioned it, the MAC will produce more torque per amp than any motor currently available which means better acceleration than any motor available :wink: ...that is why I am a huge MAC fan.

Click to expand...

Sure. torque per amp will be very high on any very slow winding motor. An equivalently wound DD will outdo the MAC handily though, as a newer MAC maxes out at something like 85% efficiency, whereas DDs designed for ebikes can hit 92% peak. More power inputted will = more power outputted, the more efficient the motor design is.

A fully saturated MAC isn't all that fast. I know, i ran 4kW into one back in 2011. A 35mm leafmotor at 4kW will absolutely dust it, and also not melt within 5 minutes - it'll throw the front wheel in the air instantly and wonder why you aren't beating on it harder, and that's on a super fast 4T winding :lol:

What a MAC does very well is create a lot of power per pound and is also still the most efficient geared motor on the market. However, it's very poor at shedding heat, so it can't output that lovely high torque for very long.

..of course, if you want ultimate power density ( usually at the expense of even more efficiency, sadly ), a mid drive is the way to go, for sure..

I disagree...here is an example: An 8T MAC has almost the exact same top speed as a Cromo if both are run on 52v...using a 60A/160A controller for both, the MAC produces a peak torque of 143 NM and the Cromo 129 NM. The MAC takes 54A to produce the 143 NM where the Cromo takes 60A to produce 129 NM. So the MAC produces 2.6 NM per battery amp and the Cromo produces 2.1 NM per battery amp.

All of the data above is using the Grin Tech Simulator.

Two reasons the MAC produces high torque per battery amp...high number of poles and the 5:1 torque multiplication you get with the planetary gear train.

Now the MAC may overheat if you need the high torque for very long but you can't beat a MAC for Torque per battery amp. The MAC will make it to the same top speed quicker plus the amps drop off as you go faster as opposed to WOT at very slow speeds/high load. Want to go over about 30 mph...the MAC is NOT the motor for you...it will overheat, a DD is the way to go. Want to ride below about 20 mph...a mid drive is the way to go and the BBSHD would be my choice . Want to ride on pavement between 20 and 30 mph and get to the top speed quickly...the MAC is the way to go :wink: . All my opinion of course but there is data to back me up :wink: .