Geared hub motors: BMC vs MAC Shanghai

[ebikes-sf]

I've been using BMC geared hub motors for about three years on most custom built ebikes, also been selling (and still am) ebike conversion kits with BMC V2 and V3 motors. I really like geared hubs for their high performance, light weight, small size / stealth, and freewheeling.

I am asked a lot "why should I pay for BMC motor when MAC Shanghai motor costs much less?". So I decided to take two motors apart and compare.

Short history (according to Chandu at BMC). BMC and MAC used to be one company at some point, and produced motors branded MAC-BMC. Then they split off; MAC continued to produce very original V1 geared hub motor without making much changes to it, and BMC has made several improvements (outlined below) and evolved original V1 design to V2 and V3.

Here are my observations:

• * Composite gears on BMC motor are significantly stronger, capable of handling 1000+ Watts. MAC's nylon gear are rated 500 Watts max - #4. MAC's 1000W motor is not any stronger than their 500W, same clutch, same nylon gears, the only difference is that it's wound for higher RPM.

• * BMC has axle seals that prevent dust and moisture from getting inside, I've tested BMC motors in heaviest rains and never had an issue. MAC motors do not have seals - #7 & #9

• * BMC hub is potentially sturdier because it is one solid piece where MAC consists or two pieces - #6 & #7

• * Lastly, my dealings with both BMC and MAC proved outstanding customer service, for US customers BMC is easier to deal with for warranty replacements since they're based in US, Los Angeles (manufactured in India), and MAC is based in China. I heard some complaints about BMC not being very helpful in arranging replacements but that's because warranty replacements must be handled by dealers, BMC has been nice enough to deal with individuals but they don't really have much capacity for that, if a dealer tells customer to deal with BMC directly for warranty related issues, they're not doing their job.

To conclude, in my opinion 2-3 times price difference between two motors is justified, you get what you pay for. MAC motor allows to get a geared hub for a price of direct hub, and it will work fine for recreational riding at lower power levels and can be upgraded with either BMC composite gears, or one metal gear (1 is enough, 3 metal gears will be way too noisy) to handle same power levels ans BMC hubs. I don't have any data on quality of MAC's clutch/one way bearing, but it looks exactly like new once piece BMC V3 clutch, much stronger than pre 2010 BMC 2-piece clutch (pics/details: http://ebikessf.com/V2-vs-V3-clutch. For all weather commuter, I would certainly go for BMC motor because it is water resistant due to axle seals.

 

[GCinDC]

nice pics. can you explain to a hub motor guy how the gears engage, from a riding perspective? is it like having three speeds? i've always been curious. at 3kW, i figured i'd trash the gears, but if the gears get me up to 40mph at $kw?, well, i'm curious...

ps. it looks like significantly more grease on bmc?

 

[snowranger]

Thanks for the informative review Ilia. My V1 BMC produced 2007 is more like the MAC you show with respect to the lightening holes. Thankfully, I replaced the nylon gears and clutch with the V2 ones eons ago, and that hub has done 5000 more miles since. I am not sure mine is sealed or not, but it has not taken on any water after many wet rides.

 

[johnrobholmes]

The stator support shown with lightening holes on the bmc, I broke on my Mac running on 45a and 66v. Certainly a weak point of the MAC design.

 

[litespeed]

I can't compare the BMC to anything else since it's my first e-bike motor but I can tell you it works flawlessly. Ilia really set me up right. Mine is running 18s3p lipo 5000 mah cells pushing my 215 lbs 6'-4" body on an extra large Specialized Crossroads Hybrid sitting upright (it's a comfort bike and I want to be comfortable!!!) at 33.8 mph and the ability to climb every hill I have come across really fast. 35 mile range and a light weight system is a great combo.

I just got my cruise control from Ilia on Saturday and man is this thing cool. Set it and forget it. I have so much torque available that cruising at 25 mph on flats and hills and only the largest hills slow me down a tiny bit. Most places it stays about perfect keeping my speed the same. Tom gives Ilia and BMC 2 thumbs up. My build, http://endless-sphere.com/forums/viewtopic.php?f=6&t=21516

[youtube] http://www.youtube.com/watch?v=izPaTBKjjAc [/youtube]

Tom

 

[knoxie]

nice pics. can you explain to a hub motor guy how the gears engage, from a riding perspective? is it like having three speeds? i've always been curious. at 3kW, i figured i'd trash the gears, but if the gears get me up to 40mph at $kw?, well, i'm curious...

ps. it looks like significantly more grease on bmc?

Hi G

No the gears are there just to reduce the rotors rpm they are still all single speed (multiple gear changing would be amazing though) they are great motors very light and powerful however they wont stand up to the sort of power you push through your motor for extended periods without breaking, the gears and the clutch are the weak point, if you keep the power levels down to 1.5KW or so they work great, they climb hills very well.

 

[biohazardman]

If you don't look closely there doesn't seem to be allot of difference. If you do then the extra screws, thicker metal and better bearing on the cover plate, balancing holes and lightening cut outs in the magnet pan as well as the stronger composit gears with a bit more grease shine through. The lightening holes show that they did just that little bit extra to make things a bit better. BMC has just enough to make it a better motor. Now if they would just pay a bit more attention to the way the axles are machined I would appreciate it. Thanks for the comparison pics.
Oops almost missed the spring around the wires exiting the motor to prevent chafing.

 

[cell_man]

No offence Ilia but that is hardly a review. The thing that made you lose credibility in my eyes was when you stated

• * 2 lbs weight difference. BMC weighs 10 lbs, MAC 12lbs. BMC motor weighs less due to less metal on rotor and stator, see #4 & #5.

Here's a picture, clearing showing a 500W Mac weighs 4.27kg or 9.4lb:



I can understand you have got to protect your primary product, but a lot of the stuff you said is no more than an opinion and just comes across as a largely ungrounded dig at a competitors product. I know that if you do a search on BMC motors on ES there are lots of folks who had problems with BMC and what was it someone was saying recently.... something along the lines of the BMC is temperamental like an Italian sports car or some BS like that. There is also a fair bit of critism around because the MAC is too cheap. Well the only reason they are available as cheap as they are is because I bought a fairly large quantity at a pretty good price and I sell them at a low margin. The other place they are available at a good price is BMS battery and anyone can see that a lot of their prices have very little margin. I know I can buy a rather popular DD hub motor in a rim for only about 60% of the price I had to pay for a bare 500W MAC. The only reason the MACs are available at DD prices is because they are available at a price much closer to the factory price. I know of a few suppliers that are selling MAC motors at BMC prices or even a bit more, they sell them too and without problems or complaints.

The only thing the BMC has really got over a MAC is that the Green gears are likely a bit stronger than the White nylon gears the MAC has been using. You advise that the BMC should not be run at over 1500W peak but the folks that are breaking MAC gears are generally running peaks above 2000W. When MAC have solved those gears issues and they will be solved soon, there will not be any real advantage of the BMC over a MAC. MAC claim 500W rated output, BMC claim 600W for basically the same performance motor. The BMC 1000W is no more than a faster wind of their 600W but it costs more than their 600W?? MAC don't claim a seperate 1000W model that costs extra, they generally just state that the motor will deliver 1000W OUTPUT power when run at 48V instead of the rated 36V where it will deliver 500W rated OUTPUT power.

 

[full-throttle]

cell-man is right - there are a few updates, but the only substantial one is the gear material

its up to the user to decide if the upgrades are really worth the extra pennies

personally I've contacted both companies and found that MAC has superb customer service

 

[NeezyDeezy]

Is anybody selling MAC hubs pre-built into a wheel?

 

[full-throttle]

http://endless-sphere.com/forums/viewtopic.php?f=31&t=19971&start=105#p330951

 

[whatever]

what happened re: the issue of wires burning out inside the axle, due to axle hole diameter not allowing for thick wires to
the motor? I dont think that has been resolved.

 

[ebikes-sf]

No offence Ilia but that is hardly a review. The thing that made you lose credibility in my eyes was when you stated "2 lbs weight difference..."

cell_man, you're right, my apologies, this was simply wrong, all I can say in my defense is it was unintentional. I removed this comment and added new photo showing MAC and BMC actually weight amost the same (all other facts are true though).

I can understand you have got to protect your primary product, but a lot of the stuff you said is no more than an opinion and just comes across as a largely ungrounded dig at a competitors product.

My intention was not to demote MAC motors but rather to address frequently asked question "why should I pay more for BMC motor", and as I stated above, the facts I presented are my obseravations/opinion. I would very much like to see MAC motors improve and create direct competition to BMC so they would drop the cost.

I know that if you do a search on BMC motors on ES there are lots of folks who had problems with BMC...

No doubt about that. Besides quality issues, geared motors in general are much less tolerant to abuse than direct drives and good portion of reported failures comes due to overpowering. Let me share some common BMC failures I encountered in the past:

FACTORY DEFECTS:
- key between axle and freewheel not inserted correctly and slips out usually during first 100 miles, may cause gear damage. The issue was very common till recently, I haven't encountered it in a few months.
- stator is incorrectly placed on the axle and eventually starts damaging windings, not very common, I only seen it a couple of times.
- two piece clutch starts separating, this was actually the most common failure till BMC started using once piece clutch (http://ebikessf.com/V2-vs-V3-clutch). Most of the time it was caused by overpowering, but often the center piece was not pressed far enough in to the gear ring and would start separating after a few hundred miles. No longer an issue on recent BMC V2 and V3 motors, MAC clutch is one piece as well.

WEAR AND TEAR:
- hall sensor failure, usually caused to overheating, more common on V2T motors since they take more amps at lower rpms.
- clutch stops freewheeling, not very common.
- clutch starts slipping, not very common
- stripped gears, rarely an issue on new motors
- stripped axle key groove, often caused by overpowering or by controllers with rough start / stutter effect

 

[cell_man]

No worries Illia.

As I said, the only thing I really feel that BMC has over the MAC is they have a stronger gear material. Pretty much the rest of the differences are fairly insignificant in my opinion. MAC have been playing with some new gear materials but haven't released these yet.

- Is it better to have only 1 removable side cover? Yes it is but not because of the additional strength IMO. It's more the possibilities that this design opens up.
- Is a hub with 2 removable covers strong enough? Yes most definitely IMO.
- Is 12 bolts securing the side cover stronger than 6 bolts? Yes I would have thought so.
- Is 6 bolts strong enough? Yes most defititely, they are only supporting the forces generated by the disk or freewheel, the motor output is coupled directly to the spokes, not through the side covers and I've never heard of a failure.
- MACs latest design uses a stainless steel insert for the freewheel and this was done prior to your comments. That picture you posted looks like a stainless insert as well to be honest, rather than Aluminium. I never had any reported problem with the Aluminium until very recenly and it turned out to due to the way they had been machined in the recent batches.
- MAC use vents on the rotor on most of their other motors and may also use them on this hub motor in the future, but they said they wouldn't go as far as BMC have gone with removing material. It's not a particularly expensive additional process to do this.

I haven't personally had so many issues with the MAC other than they can be a bit difficult to drive with some controllers and the gears can break occasionally, but I really don't have so many people complaining of broken gears. I had 1 case of the freewheel thread breaking off and that was 1 of the new batch with a black case. Mark has complained that the posts for the planet gears come loose, but I've never heard of this issue from anyone else. I know that the keyway can become a little deformed with hard use but the motor is with a freewheel so I can't see how a small deformation or a little play in the keyway will cause an issue, but that's just my thoughts. I don't recommend they are used for off-road use. I'm doing over 30kms a day commuting on a 500W MAC running about 2000W peak and it's standing up fine, gives me about 50kph max speed on 16S A123.

Cheers
Paul

 

[jonescg]

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

 

[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.