How long does a geared vs direct drive last?

Looking to do my first E-bike conversion...and I've got 2 projects in mind. One is a trike, the other a mountain bike.

I'm having a huge debate over geared or direct drive hub. I really like the geared hubs for 2 reasons. They are light, and they can free wheel. I plan on lots of pedaling without batteries, and don't want the drag.

I've been scared off because of reliability reasons, but I have no real experience other than what I've heard.

I'm looking at a BMC V4 motor at approx 1000W. From what I understand , this is well below the current power capacity, so it should last a lot longer than running it at 2000W?

The BMC V4 has the glass impregnated composite planetary gears right? Why not make them steel? Are they replaceable?

How many miles can I expect to get out of my BMC unit at 1000W power?

Comparing to a direct drive unit, the Crystalyte HS3540, how many miles will it last at 1000W?

Thanks for the info!

By comparison, a geared hub will last only a fraction of the time. But a Direct drive should last nearly forever. Or atleast as long as the bearings hold out, and bearings can last for .. well, your great grand children might decide to replace the bearings to keep the motor running, when they get old. (the great grand kids, not the motor)

So by comparison, the Geared hub will be shorter lived, since gear teeth do wear against each other, a little. But how long can a plastic gear last? I would guess several decades.

Geared hubs are more sensitive to abuse, though (Relitivly). So how long it lasts depends on how you treat it. If you treat it well, I imagine it will last a very long time.

In a geared hub, the gears and clutch are subject to wear.
The BMC and MAC have parts that are easily replaceable and very available though, so it's not like they are trash if those parts wear out.

If you are concerned about money, you should consider a MAC motor. it's almost half the price and the replacement parts cost drastically less $.


Drunkskunk - the gears in the BMC and MAC motors are no longer just plastic/nylon, they're a fancy composite material that is much stronger. I had an earlier motor with the original nylon gears in it, which were fine for a few thousand miles ( and looked brand new the entire time ) until i decided to run 4kW on them, which ended up melting and destroying them.

I couldn't kill them on 2600w peaks. They were pretty dang strong. The new composite gears are even stronger.

Something along this line - are there any DD motors which are about the same size as the mac/bmc motors ?

Running at normal voltages both motors work equally fine. When you start to posh 60+Volts into a geared motor it does not like it much.

That is when a DD shines especially if you do some mods to help it stay cooler.

I am about to the point where I want a DD motor that's around the size of a MAC/BMC , but will take higher volts.

First off, there is very little resistance on the HS3540 motor when you don't use regen. : )

unclejemima said:

I'm looking at a BMC V4 motor at approx 1000W. From what I understand , this is well below the current power capacity, so it should last a lot longer than running it at 2000W?

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Intuitively yes, but I am not 100% positive. It will definitely be easier on the clutch. I think what you should look at is how abusive the roads you will run your motor on is. I notice my clutch lasts longer if the roads are smooth, but then once i hit a lot of cracks, then it all goes to shit pretty fast. You can hear the clutch fail before it actually failing.

unclejemima said:

The BMC V4 has the glass impregnated composite planetary gears right? Why not make them steel? Are they replaceable?

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Don't know about impregnated composite on the gears, but they are not steel probably due to noise and heat. There might more friction due to the steel. I think Illa uses one steel and 2 composite for the best mixture between durability and noise. And yes they are replaceable. It just takes some time. Illa has some video to do so. They say you need clamps to remove it, but I found, I don't really need it.

unclejemima said:

How many miles can I expect to get out of my BMC unit at 1000W power?

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Ideally a lot if you don't run it on broken roads or at least have it on a Full Suspension bike. My first clutch lasts ~2000 miles before dying. It was partly my fault. I was running it on hard tail with 40lbs battery on the rack on the rear wheel. Combine that with broken roads. Well you get the picture. Just grease the clutch every 3K miles or so and run it on smooth roads, and you should be fine for a long time. The second didn't fair too well due to running it with incompatible controller. So make sure the controller is compatible.

unclejemima said:

Comparing to a direct drive unit, the Crystalyte HS3540, how many miles will it last at 1000W?

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I don't have a fair comparison because I run my HS3548 on a Full suspension and have almost no weight on the rear beside me. But 2K miles so far and it's running fine just as the day I got it.

Steel gears are very noisy and tend to wear out quickly. They may wear the outer ring gear fast too, and that is not easy to replace.
otherDoc

It sounds like you would benefit from a Mac/BMC quite a bit, over a DD. They are significantly lighter and as said, no drag when the motor is unpowered.

I put about 3k miles on my old Mac with nylon gears, mostly at 800-1200watts and they (and the clutch) are not showing any signs of fatigue. A proper matching controller helps a I'm told.

I'd highly recommend buying the Mac 500/1000w kit with eb312 controller from Cellman.

Also, at 1000watts, a geared Mac/BMC will give more performance than a DD on hills and below ~20mph.

docnjoj said:

Steel gears are very noisy and tend to wear out quickly. They may wear the outer ring gear fast too, and that is not easy to replace.
otherDoc

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Yeah you do not want those at all. Those were made before the composite gears came out. I've never seen anyone shred the composite gears. I've seen clutches and stators die way before composite gears die.

Great reply's, thanks guys. 10 out of 10. Keep 'em coming

I only plan on running 1000W 48V on the DD or Geared unit.

On the trike, I don't plan on taking it off road. Smooth roads only...

But the mountain bike is a hard tail...a light weight old-school GT Bravdo Cro-mo. I was only planning on running a mid-frame mounted 10A battery, and perhaps only 750W of power to help on those really long off-road climbs.

Am I going to trash the motor with rough off-road use? Would a DD hold up better?

Is there any direct drive motor similar in size to a DD unit? Anything? Even for 500W levels?

Thanks!

Well, doing more reading...I found this thread...

http://endless-sphere.com/forums/viewtopic.php?f=3&t=11403

the conclusion I got from this thread was that a good DD motor's re-gen will be barely noticeable. The one guy said he coasted down a hill beside a non-EV bike, and was approx 1 bike length behind by the time they got to the bottom. Of course, it all depends on the grade, rider weight, tire pressure, ect, but gave a fairly descriptive comparison for those noobs like me

One guy in that thread said it best "Its about like riding 10 pounds low on a 90 pound tire."

I think I can handle that. A trade off I'm worth considering, especially if I plan on riding off-road, I don't want to keep replacing geared units.

Looks like my only real choice for hub motors is the 9C at about 15lbs. That's still pretty heavy. About x2 of a similar geared unit.

Looking for advice for those who have run a BMC or similar geared unit off-road. Sure the new gears can take the abuse, but is the clutch still going to fail prematurely?

Is it a co-incidence that the Stealth Bomber bike runs a DD hub?
Looking forward to your reply's,

The bomber runs a DD because it's easier to get bursts of really high power out of them without destroying them either by stripping teeth on gears or by damaging things with heat buildup (because it is easier to get rid of heat from the stator/magnets on a DD than a geared hub, as there is one less layer of air and casing between the outside on a DD).

When you say regen, you mean motor drag, right? because those are two different things.

Regen can be so strong that when you hit the eBrake to engage it, you need to put a death grip on the bike to prevent falling off... all the way to more like a badly aligned vBrake.

Hub motor drag varies quite a bit from motor to motor. It's called cogging actually. And a 9C isn't too bad in terms of cogging, but you do notice it.

BMC and MAC motors are virtually identical so all the same issues and power handling level apply to both of them.
Nobody makes a large geared motor, so all the higher power setups are mainly direct drive.

I've found the amount of cogging really varies by controller. Some of them are atrocious, and others are really very good, on the same motor. I use several KU123 cheap BMS battery 48V controllers, and the lack of cogging on a 9C is very good. Noticeable, but way less than some of the other controllers I've tried, either Crystalyte sensored or unsensored or HTB

The way to avoid cogging, drag, or whatever you want to call it with a DD motor is just to set cruise control to about 2mph less than what you want to go and then pedal up to the speed you want. It will be just about the same as with a freewheel and will actually charge the battery

I can vouch for the reliability of the BMC geared motors. I've been using them on my long 70-mile commutes for nearly 3 years now and probably logged over 25 thousand miles on them. I like these motors. I have 5 BMC motors total (two V3's , two V2-speeds, and one V2-torque). I got most of my motors before MAC became a serious geared hub motor source at the beginning of 2011.

If you want reliability out of these motors the biggest thing to know is to keep the continuous power below 1200 watts. I've melted phase wires and blown hall sensors on one of my V3 motors but only because I was putting 1800+ watts continuously while I was riding off-road with it up fairly steep climbs.

My favorite and mostly used BMC motor is the V2-speed because it has smooth and powerful response thru the speed range I spend most of the time at (0 - 32mph) and for my uses it is the most efficient. The V3 motor is only more efficient at 30+ mph, but it's also responds noticably more twitchy at low speeds.

I've been keeping up on the improvements of these BMC motors over the years and from what I understand the V4 motor you're looking into is actually the V2 with more heavy duty wiring, better/smoother (1-peice clutch) and improved composite planetary gears. That's why the V4 is rated at 1000 watts and V2 motors are only rated at 600 watts. Yet I've never had a clutch or planetary gear go bad on any of my V2s. I've actually had a bearing (on the side cover) wear out and grind on me at around 12,000 miles (I eventually replaced it) but clutch and planetary gears were still going strong.

unclejemima said:

Looking to do my first E-bike conversion...and I've got 2 projects in mind. One is a trike, the other a mountain bike.

I'm having a huge debate over geared or direct drive hub. I really like the geared hubs for 2 reasons. They are light, and they can free wheel. I plan on lots of pedaling without batteries, and don't want the drag.

I've been scared off because of reliability reasons, but I have no real experience other than what I've heard.

I'm looking at a BMC V4 motor at approx 1000W. From what I understand , this is well below the current power capacity, so it should last a lot longer than running it at 2000W?

The BMC V4 has the glass impregnated composite planetary gears right? Why not make them steel? Are they replaceable?

How many miles can I expect to get out of my BMC unit at 1000W power?

Comparing to a direct drive unit, the Crystalyte HS3540, how many miles will it last at 1000W?

Thanks for the info!

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Holy crap Sacman! That's some serious commute mileage! Really impressive.

Your results show how long lasting stuff can be in "normal use". Trouble with many of us is, we don't use them normal. Safe enough to say that few hubmotors are designed with tough trail riding in mind, both the shocks and the extra steep hill climbs.

Bottom line, for street use on terrain less than 10% grades, pick the motor you like the best for your reasons. Freewheeling motors can be great, but it's true, only a tiny trickle of power is needed to eliminate motor cogging if you want to hypermile and pedal a lot. Either type should last as long as your bike does.

But if you plan on trail riding, then you need to expect more wear and tear and less lifespan. Clutches may wear, and if the riding is tough, either type of motor can melt easily. Generally, if you have steep trails to ride, you will want, if not actually need, at least 1200-1500w of power or more. Any less is a joke on a 15% grade.

wesnewell said:

The way to avoid cogging, drag, or whatever you want to call it with a DD motor is just to set cruise control to about 2mph less than what you want to go and then pedal up to the speed you want. It will be just about the same as with a freewheel and will actually charge the battery

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It won't charge the battery in that situation. Thats False. Setting the motor at 2mph less than your target speed, you're using mostly motor power. Follow Dogman's advice to reduce cogging, or you can unplug the motor from the controller and reduce the cogging to a great extent.

Thanks again guys.

Sacman, did you ever consider running auto tranny fluid in your BMC's? I've heard guys do this to dissipate heat and improve gear life. Don't know why they don't offer this as a factory option if it works so good?

With so many miles on your BMC's, how often have you had to replace the planetary gears?

How much off-road riding did you do with yours? Hard tail or Full Suspension?

Yes, the V4 motor is actually the V2 with more heavy duty wiring, better/smoother (1-peice clutch) and improved composite planetary gears...or at least this is what I've been told. With these improvements in the V4, perhaps I can get 5-10K miles on it with 50/50 commuting and off-road use.

The guys at High Power Cycles are running a V4C (custom version of the V4 with different wires I think) and are saying 2000W is the perfect mix of performance and power. I think I will still stay at 1000W and stay safe. I'm only 150lbs, and I respect the motor by not working it to hard.

I know I really should go with the 9C, but I just don't like the added weight and visual dis-appeal of the large hub motor.

Does ebikes.ca sell BMC motors, or where is the best place in Canada to get the BMC units?

wesnewell said:

The way to avoid cogging, drag, or whatever you want to call it with a DD motor is just to set cruise control to about 2mph less than what you want to go and then pedal up to the speed you want. It will be just about the same as with a freewheel and will actually charge the battery

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I don't understand this statement. If you are charging the battery via the motor (via any method I am aware of) you will always have drag on the bike, and probably cogging as well (though the latter depends on the design of the motor and controller).

If there were no drag on the bike, you are getting free energy...and we all know that's not possible.

So cogging is only with DD motors, right?

Any non-freewheeling motor, or any freewheeling motor being run in reverse by backing the bike up, for instance.

Drunkskunk said:

wesnewell said:

The way to avoid cogging, drag, or whatever you want to call it with a DD motor is just to set cruise control to about 2mph less than what you want to go and then pedal up to the speed you want. It will be just about the same as with a freewheel and will actually charge the battery

Click to expand...

It won't charge the battery in that situation. Thats False. Setting the motor at 2mph less than your target speed, you're using mostly motor power. Follow Dogman's advice to reduce cogging, or you can unplug the motor from the controller and reduce the cogging to a great extent.

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You're mistaken. I do it every day. Once you get the rpm past the no load speed of the motor, current reverses and charges the battery. I can watch the pack voltage go up. Of course you need a meter that measures in tenths to see it.

wesnewell said:

You're mistaken. I do it every day. Once you get the rpm past the no load speed of the motor, current reverses and charges the battery. I can watch the pack voltage go up. Of course you need a meter that measures in tenths to see it.

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Are you sure about that? It sounds like the small increase in pack voltage (that you percieve as "charging the battery") is actually a reduction in pack voltage sag because once you start pedaling you're putting a lighter load on the battery. Don't you notice your watts decrease too when you start pedalling? It's got nothing to do with reducing/elliminating cogging. BTW the CA does measure down to 10ths of a volt.

Unclejemima,

I thought it would just easier to answer all your questions in a different color (red) below.

unclejemima said:

Thanks again guys.

Sacman, did you ever consider running auto tranny fluid in your BMC's? I've heard guys do this to dissipate heat and improve gear life. Don't know why they don't offer this as a factory option if it works so good?

Never tried ATM fluid because I never felt the need to and also because I don't know if it's safe. Isn't ATM fluid for metal gears? Is it even safe chemistry for composite gears? It won't slowly eat 'em away will it? The only lubrication I put on the gears is what the manufacturer puts on them... Mobilgrease 28. It's a synthetic aircraft grease with clay thickeners.



How much off-road riding did you do with yours? Hard tail or Full Suspension? Untill the past 6 months I've not done any off-road with my ebikes. They were all purpose built for just commuting on streets, bike trails, or unpaved hard pack trails. I did recently built an off-road downhill bike but I put a 9C motor in that.



With so many miles on your BMC's, how often have you had to replace the planetary gears? I've never had to replace any of my planetary gears. They all seem to still run smooth and quiet. I can actually attibute a lot of long motor longevity to the fact that I've learned not to hammer down on my motors too hard while I'm commuting. I've got many miles between home and office and I hate breaking down. Put it this way... cars made today can easily do 120mph right? But how often do you drive it near 120mph continuously ... and how long do you think it will last if you keep driving it that way?



Yes, the V4 motor is actually the V2 with more heavy duty wiring, better/smoother (1-peice clutch) and improved composite planetary gears...or at least this is what I've been told. With these improvements in the V4, perhaps I can get 5-10K miles on it with 50/50 commuting and off-road use.



The guys at High Power Cycles are running a V4C (custom version of the V4 with different wires I think) and are saying 2000W is the perfect mix of performance and power. I think I will still stay at 1000W and stay safe. I'm only 150lbs, and I respect the motor by not working it to hard. I straight up just don't trust HPC and I recommend you don't buy from them. Lot of the folks on this forum would agree. HPC has a track record of advertising that their products have superior performance than others but rarely can or do they back it up with hard technical data and tests.



I know I really should go with the 9C, but I just don't like the added weight and visual dis-appeal of the large hub motor.
The 9C has been fantastic on my off-road DH bike. So far I think it's a pretty awesome motor as well. One more thing to consider is motor noise an issue for you? Because geared motors like BMC or MAC will always be slightly louder than DD motors like the 9C. Not by much but definitely noticably louder.



Does ebikes.ca sell BMC motors, or where is the best place in Canada to get the BMC units? ebikes.ca does not sell BMC... I don't know any BMC vendors in Canada. But I can definitely recommend ebikes-sf.com That's illia in San Francisco. He's the best.

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Thanks guys.

Can the 9C accept a 8speed cog-set?

Where is the best place to buy the 9C? Any dealers in Canada?

Thanks!