Geared hub motors: BMC vs MAC Shanghai

[Spacey]

I've done that lot's of times..... you need the large washer to go between the wheel and the freewheel.

[jonescg]

Ahah! Thanks for that Spacey!!

[cell_man]

Hey Paul,

The motor we bought for Katherine's e-bike is a direct drive, but when I tried to thread a Shimano 7-speed freewheel onto it did OK until the last bit where it tightened up but now it won't freewheel Hope I haven't stuffed it...

CHRIS

Hey Chris,

That's a bit strange, nobody else has reported any issues like that and I've sold a few of them. Best to send me a PM or email if you have an issue as this thread is not related to the direct drive motor. I'll try to take a look at 1 of the motors with a freewheel and see if I can see anything amiss.

cheers
Paul

[jonescg]

No worries.

Cheers,
CHRIS

[USMC7578]

Good Morning. I have the V2 I lost power to the rear wheel. The motor is running but no power to the wheel. I have it apart to the 3 green gears. I believe they may be worn (although I see no signs of plastic in the hub). Are those gears replacable?

Mike

[neptronix]

usmc; the gears are replaceable.

[ebikes-sf]

Good Morning. I have the V2 I lost power to the rear wheel. The motor is running but no power to the wheel. I have it apart to the 3 green gears. I believe they may be worn (although I see no signs of plastic in the hub). Are those gears replacable?

Mike

Gears are rarely a problem, it sounds like a separated V2 clutch:
http://ebikessf.com/V2-vs-V3-clutch

It can be fixed by welding two pieces together - very carefully though, to avoid overheating. Something I can do for $20. Or new V3 one-piece clutch and gears is $110.

ilia

[IIIHorseman]

There is another benefit of the BMC motor vs the MAC that has not yet been mentioned. The clearance and fitment of the BMC motor is superior. If you look at the motor case of each of the motors, you can clearly see that the BMC version is not as elevated and actually is contracted by the case screws. On my MAC motor, the stock disc caliper rubbed up against the casing; and even when I took off the disc brake, it was still rubbing up against the motor screws. I had to eventually buy another caliper and slightly modify it to get it to work. There also doesn't appear to be enough room to add a 8 speed freewheel (even with a spacer), short of bending the frame. If I knew this before hand, the added expense for the adjustments pretty much off-set the cost to prefer the BMC. The BMC axle and connectors also appear to be of better quality. Fortunately Ilia, from EbikesSF, is one of the few vendors that have both options to choose from.

[Spacey]

Gotta say, I've never really had a problem fitting the Mac motors with disc brakes. You've just got to get the right amount of spaces on the right side of the axle. Have done about 4 Mac builds so far.

[neptronix]

Kinda sad that the main difference, functionally, is rear disc brake fitment.
Supposedly they have better water seals? i have not seen pictures of these seals..

Is that worth $200 to you, is the question!

I didn't have problems with the disc brake caliper rubbing against the cover. But i agree that disc brake fitment is a little on the painful side. These are pretty wide motors after all.

[ohzee]

I noticed that the BMC motor has holes on the cover between stator and gears. .Does anything think drilling similar holes
in the MAC would be beneficial for cooling ? Running my mac near the limits I am trying to figure out some way other then
filling it with oil to help keep it cooler or reduce cooling times between runs.

[neptronix]

I noticed that the BMC motor has holes on the cover between stator and gears. .Does anything think drilling similar holes
in the MAC would be beneficial for cooling ? Running my mac near the limits I am trying to figure out some way other then
filling it with oil to help keep it cooler or reduce cooling times between runs.

The new magnet assembly in the MACs has these holes.
It might help, but it also opens up the possibility of getting grease on the stator.
You also end up shedding stator heat towards the gears.

I don't know if it's really beneficial at all. The benefit might be more in shedding weight from the motor.

[ohzee]

Good point that the heat will go the wrong way. I just liked how BMC had the holes there.

Leaves me with drilling holes in the covers then. Mine is a mid kit so at least it's a bit safer from road debris.

[cal3thousand]

All this talk makes me itch for the new 7T that's (hopefully) on the way soon from cellman

[neptronix]

Prepare to have to do regular oil changes if you do that .. the grease inside will get dirty over time due to dust and other stuff in the air.

cell_man seems to be working on producing a larger MAC motor soon, FYI.

[RyanTo]

Any truth to the BMC being better in the rain. Is the Mac that bad? I live in the PNW but I have covered parking at work and at home. Still, sometimes it will be raining on the way. I was thinking about buying a MAC..

[teklektik]

Talk to Ilia at Ebikes SF - he now sells both.

[MalcyW]

Has anybody been able to compare the noise levels between a BMC and a MAC?? Are they much noisier than direct Drive hubs?

[DAND214]

My MAC"S are as quiet as most of my DD's since they have a growl under load.
They also seem to quiet down after a feww hundred miles or less.
Both are 8t in 26" wheels running 15s LiPo's great power for such a light motor.

Dan

[veloman]

My Mac hubs are quieter than my 9c hubs. There is a slight 'whine' with the Macs, but it's less noticable than the DD noise - which is still very quiet. They are worlds quieter than that gear reduction Currie motor I used years ago