Durability geared motors (MAC / GMAC) vs. direct drive (9C, Crystalite...)

Hi,
I wonder if some of you have tested MAc or GMAc motors on very long mileage (> 20'000 kms).
If yes, what is the durability of the components ? Do the gears last long, or do they need a frequent replacement ?
How does it compare with DD durability ?

Would totally depend on the use case.

Heavy weight going up big hills?

Let’s assume both scenarios :
1/ light rider on flat area
2/ heavy rider on hilly area

2 MACs, 10T and 12T.
5,000 + miles each. First time apart. Gears have at least 50% life remaining. Replaced gears and clutch in one because I had spares.

They're mounted on trikes and resides in steep foothills. Safe to say they get a workout (52V 35A).

Thanks for your feedback

On my side I have done ~5000 km with my GMAC 8T, used mainly > 800W (up to 1500) and flat lands, it’s in perfect condition.

Question : I plan to install a temperature sensor on my GMAC. Do you know what is the maximum temperature I should not exceed in order to avoid damaging the magnets and the gears ?

250 F measured inside would keep it cherry. Even 300 not bad. The varnish on the windings is a bit like your pie in the oven. 425 for long enough will blacken that crust.

If you need to change your riding habits to keep your motor from overheating, it is time to buy a bigger one. Temp sensors are more important than a speedometer on ebikes. For me, monitoring battery temp is a must. Motor comes second and should be paired with a controller that handles temp data.

dogman dan said:

250 F measured inside would keep it cherry. Even 300 not bad. The varnish on the windings is a bit like your pie in the oven. 425 for long enough will blacken that crust.

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Noted, thanks !

@Mad Rhino : changing my motor is an option, but I like the light weight of the GMAC, as well as his capabilities at high and very low speed, even in 8T with my 29’’ wheel.

@all : any other feedbacks about gears durability on your Mac/Gmac motors ?

Gears used to get soft, melt and turn into peanut butter gears. That was in 2008, when they used low melting point plastic. That stopped being a problem a long time ago.

Once in a blue moon, people have issues with the gears internal freewheel, or the shear pin, but generally only when really abused. So you don't jump them like you are in the x games. If you do a little pop, get off the throttle when you land so the motor will freewheel on landing. You can melt the motor in a very short time by overloading it. The tests I did for e-bikekit.com showed that total weights under 300 pounds are safe, even while climbing hills of 8% grade. Total weight is the bike, you, the bike, the motor kit, the battery, the water in your bottle, etc. The motor can get quite hot but still be fine. But overload enough, and it can melt inside before you can even feel heat on the outside. So don't put 400 pounds on one, and ride the rocky mountains.

Pretty much the same weight limit for the e-bikekit dd motors. But both types increased the weight limits if the wheel is only 20" rim. This is why I built this bike, after the testing. I never overheated this dd motor, even at 400 pounds weights up the mountain I rode to kill motors in the testing.

We have a pair of MAC 10T's we've been running since 2015 on HPV trikes.
1800 watt peak and they see that often - sometimes sustained for up to about 20 minutes on a climb - battery limited.

After 5000 miles the gears and clutch still have over 60% life left.



So in the reliability race one has more parts to fail, the other has more heat to initiate failure. Not a lot of difference in the long run.

Hi Jil, bonjour (!)

I had a 8t Mac hub motor on my two former setups (58V battery): a diamond frame bike and then a recumbent. The Mac was not very reliable. The Mac clutch failed after 6000 km. I changed it myself. Mac motor is good for 35 mph but get hot after 25 miles, close to 90 C. I cannot climb high gradient (8%) without overheating the motor. It can climb a short 15% gradient but it overheated easily. i had to stop for 10 min.

Then for touring on my recumbent I switched to a MXUS 3000W direct drive with a 72V battery (20s) and I added statorade cooling fluid inside the motor . it is really another world ! 42 mph continuously without any issue with 2100 W! I barely reach 45 C after an 80 miles trip. I can climb 8% gradient at 35 mph and I have seen 65 C. I climbed last week a 20% gradient over 1 km after I done a 40 miles trip and reached 75 C. The 12F Nucular controller was maybe overheating (I put it inside a box) when I did a 20% gradient as it reached 105 C but not the hub motor. and I can use regen with a direct drive which is great to stop your bike at 40 mph and when going downhill. No more brake pads to change very 2000 km and so efficient and so safe even in rain. The only drawback is that the direct drive is much heavier than the mac motor but I don’t give a monkey since I don’t have to lift my bike.

Go for a direct drive.

Best regards,
Peterfr12

That is some great info, thanks for sharing.
How much was the total weight on your ebike including your body weight with the mac motor, and was it 26" wheels?

Peterfr12 said:

Hi Jil, bonjour (!)

I had a 8t Mac hub motor on my two former setups (58V battery): a diamond frame bike and then a recumbent. The Mac was not very reliable. The Mac clutch failed after 6000 km. I changed it myself. Mac motor is good for 35 mph but get hot after 25 miles, close to 90 C. I cannot climb high gradient (8%) without overheating the motor. It can climb a short 15% gradient but it overheated easily. i had to stop for 10 min.

Then for touring on my recumbent I switched to a MXUS 3000W direct drive with a 72V battery (20s) and I added statorade cooling fluid inside the motor . it is really another world ! 42 mph continuously without any issue with 2100 W! I barely reach 45 C after an 80 miles trip. I can climb 8% gradient at 35 mph and I have seen 65 C. I climbed last week a 20% gradient over 1 km after I done a 40 miles trip and reached 75 C. The 12F Nucular controller was maybe overheating (I put it inside a box) when I did a 20% gradient as it reached 105 C but not the hub motor. and I can use regen with a direct drive which is great to stop your bike at 40 mph and when going downhill. No more brake pads to change very 2000 km and so efficient and so safe even in rain. The only drawback is that the direct drive is much heavier than the mac motor but I don’t give a monkey since I don’t have to lift my bike.

Go for a direct drive.

Best regards,
Peterfr12

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Hi,

The recumbent with the mac motor was ~35 kg and equipped with 26 inch back wheel and a 24 inch front wheel. The tyres were from Schwalbe marathon and did not have a good lifespan (dead after 3000 km) Battery 58V 27Ah. Everything was purchased from Em3ev. This bike was used to do a 40 km commute one way. It can reach 33 mph but struggle to dissipate the head.


The recumbent with the MXUS motor is ~ 50 kg and equipped with 19 inch back and front motorbike wheel. These are motorbike tyres with 3 inch wide (Heidenau) on the back and 2.25 inch on the front (Heidenau). These tyres are great and look unworn after 1700 km. I can ride on tarmac and sandy road without any issue. Battery is a homemade 82V 48Ah. This bike is designed to do long trip 150 km in a go at 35 mph on the flat without overheating the hub motor; at 43 mph I can cover 110 km. In fact, I can recharge at lunch (2h30 min) and do 200 miles in a day. That is my plan. I will add a fairing on it as I am getting annoyed with the bugs and getting cold too with the amount of air I push at 43 mph. I have not tried the Field weakening to reach higher speed. Honestly 43 mph is enough! I don’t want to have issue with the police. In a village I ride at 25 mph. the MXUS is silent.
My weight : only 64 kg for 6 foot to add to the weight of the bike.


Mac accelerates faster with 30A but if I supplied 60A (or even 80A) to the MXUS acceleration is also excellent. I am not mad about acceleration; I want a bike as comfortable as possible for long trip and reliable (i.e. Harley Davidson).

Best,
Peterfr12

Thanks to all for your feedbacks :thumb:

Peterfr12 said:

The recumbent with the MXUS motor is ~ 50 kg and equipped with 19 inch back and front motorbike wheel.

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Please post updates as this thing evolves. Quite a ride.