Most reliable Mid drive motor kit?

C

cwah

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Hello,



I had very bad experience buying few years ago 2 BBS02 kit. They both failed. They can't handle high mileage. They need to be greased as well.



I just can't be bothered to do any maintenance and decided to change to Direct drive.



But I wonder if progress have been made? Ideally I'd like a kit which would be maintenance free for 50k+ miles. And obviously easy to find part for maintenance.



Any idea? Or I stick to Direct drive?



Thank you
 
I've got over 30,000km on my BBS02 now, since I replaced the internal controller with a 25A Grinfineon I haven't had a single issue with it.

I do grease it twice a year, and I think you'll find that all mid drives have gear sets in them that will need their lubricant changed periodically, especially if you want them to be quiet and live a long time.

I'm also pretty kind to it, I don't use PAS, I keep it in the right gear, and use my legs to get myself moving before I give it full throttle.

If they're not abused, the BBS02B seems mechanically to be reasonably solid, and if you do need parts for it I don't think there's another mid drive with better parts availability.

If you truly don't want to perform maintenance, a DD hub is what you want.
 
I worked with some of the early Mid-Drive equipment.
It SUCKED

Looking around now. . . (not at kits but parts on the road)
In Santa Cruz we are converging on 50-50 Ebikes for Standard Bikes (not a joke!!!)

Most are actually mid-drive
High end
Shop Purchased

I would say... 3:1 mid drive around here.

From a longevity standpoint, I am sure all of these will fail the customer as the batteries and individual parts are so specific and so expensive and so unique. Not until things settle on some sort of AutoZone standard will it be worth it to go the route of Mid Drive...

A hub is a hub is a hub
A controller is a controller is a controller
A Pack is a pack is a pack

Unless it is all super-custom built in...

BUT
That is not what you were asking about.

I have no idea what the answer is, but I am quite interested. I would love to see some aftermarket mid-drive kits and would be more than happy to talk the wife into buying one.

-methods
 
Hmm, maybe look into the AFT cyclone 3000 kit? They do a rather extensive rebuild, and redesign of just about everything. It's $$$$$ , but known for its high mileage abilities. They get away from the grease, in exchange for a super lightweight 0w oil with a very high molybdenum content, to help with the hardened nylon gear sets that they use. The oil bath is probably going to be less intrusive to service than a grease system, I would imagine. And it screams too, awesome sound from what few videos there are.
 
I suppose you could custom machine every part in a mid-drive. It's just not possible for them to be more reliable when they have more parts to potentially break. Fifty thousand kilometers with no maintenance is a very unreasonable bar to set.
 
I done all of this . Costom

Once 1 year chage chian and sockets.

I sill have my first cyclone 7 year later.


30k seem good up time

Steel it key. Cheap ez to replace

But pay for good lipo and chages 3 set of batterys

Good lucky
 
I would think a BBSHD kit that would be detuned from the factory max amps of 30A to 20A peak would last a long time. But would still need a re-grease and sprocket&chain maintanance once in a while. Riding it like dustNbone describes riding his BBS02 is best to keep such a mid drive system happy.
 
Folks were doing mid-drive kits with 2 stages and belts a long time ago.
Bought a trike from a guy who was experimenting heavily
Not sure where all that went.

Belts are nice. . .

-methods
 
stay under 1000w bbshd very reliable

nyc cargo ebikes well over +10k miles


stay under 500w bbs02 very reliable


trouble is most users operate bbshd 1500w

or 900-1000w bbs02


not gonna last @ those levels
 
kcuf said:
stay under 1000w bbshd very reliable

nyc cargo ebikes well over +10k miles


stay under 500w bbs02 very reliable


trouble is most users operate bbshd 1500w

or 900-1000w bbs02


not gonna last @ those levels
Click to expand...

I used 2 BBS02 at manufacturer level (although I've set to the max power from the setting), and both failed within a year.
 
bbsxx

stock factory power level

exceeds continuous rating


levels 1-9 enabled

use 6 or below

will not exceed continuous limit
 
I have 2500 miles on my BBHD. No electrical problems.

Did break a tooth off of the pinion shaft but that was abuse. The motor tended to loosen up and I've let tons of people ride my bike. I'm pretty sure everyone mashing the throttle hard from a standstill (like a motorcycle) and causing that motor to rotate up and click hard against the frame killed the pinion gear. Now I instruct people to pedal like a bicycle and once moving then they can play with the throttle.

Since then I saw and copied a solution using a sailboat turnbuckle. Do a Google search for "Bafang sailboat turnbuckle" and then click on images. It keeps the motor up tight against the bottom of the downtube. MUCH more solid feeling.

FWIW when my pinion gear broke I assumed it was the nylon gear that had lost a tooth. It looked perfect and I reinstalled it. I also cleaned everything and regreased it with Mobil 28 grease as suggested here (I think).

I have not had sprocket, chain or cassette problems.
 
"But I wonder if progress have been made? Ideally I'd like a kit which would be maintenance free for 50k+ miles. And obviously easy to find part for maintenance."

The service interval for a heavy duty diesel truck is 30.000 miles. One of the limiting factors is the time between lubrication with special grease that can go that long. It would be cheaper to pay someone to service it every now and then than to keep replacing worn out motors. Hub motors put less load on the other driveline parts. So if low maintenance is what you want it's probably the best choice for you.
 
I don't know of any machine on the planet that can go 50K miles or the equivalent hours without maintenance. It's a totally unrealistic expectation that calls into question other choices or actions you may be undertaking.

That being said, I think I have close to 10K km on my BBSHD and I haven't had the motor open since installing it. I plan on doing it before the weather turns and come October it will be 2 years since I installed this kit. I ran 50A the entire time and actually bumped it up to 60A today (I happened to be on ES today looking at the opensource firmware when I saw this thread). I run the a shunt modded controlled and I make my own gaskets. Zero issues with the motor or controller, but I think the throttle may be going. I leave my bike outside all year round and I ride in the rain.

So I'm basically running double the power through this motor all year round and have had to do zero maintenance on it in 2 years. I've broken a couple cogs and I think the drivetrain is on it's way out. My winter tires are good but my summer tires will be done this season. As an engineer I'm impressed with how durable the BBSHD is operating well over it's rated design.

Grease the motor once every 5000km, check the bearings, the free play in the shafts and gears when you do, and then properly seal it back up and there's no reason you can't get 50k miles out of a BBSHD. I've seen a few people breaking rotor shafts and I'm not sure why that is. I personally suspect user error but it could be a manufacturing flaw. Other than that these motors are bulletproof with very little maintenance.
 
Just to add to the knowledge base. I'm at the end of my fourth year on my BBSHD. Just over 6,000 miles. Never opened it. Never an issue. It still runs the same (silent) as the first week I bought it. The only durability change I have made is to limit it to 25 amps (1,200 watts) mostly for the sake of chain and rear sprocket wear on the freewheel. I'm a country cruiser with most my rides in the 40-60 mile range. No one rides the bike but me. Admittedly my BBHSD has had a pretty easy life and my tube of Mobil 28 sits untouched on the shelf.....
 
ebuilder said:
If an owner accelerates their BBSHD in a tall gear ratio at 1000w's or more from a stop, you know how much stress that puts on the nylon helical gear within the motor? Tremendous stress.
Click to expand...

I think this is a big one. I occasionally forget to down shift and when I do I bite the bullet and either pedal out or pull over and lift the wheel and downshift.

With the power I'm running I can very easily get the bike moving in the 10t. It's very tempting to do because sometimes you've got traffic behind you and to be honest it's kind of embarrassing. But I don't because all it takes is one time and you can break stuff.

That's road riding, on trails it's even easier to end up in the wrong gear and power through. No matter what conditions you're geared for you can still wind up in the wrong gear and apply too much torque on the drivetrain with a motor that's +150Nm.

I decided to split my motor open today just to see what's going on. You'd be hard pressed to tell the difference from I had open prior to installing it. The grease is now black instead of grey but the bearings are turning smooth (there's still some of the synthetic grease I added in the housing untouched. The gears themselves are perfectly coated and the grease hasn't migrated away from the contact surfaces). No signs of water ingress in the gears, controller or stator. I haven't opened up the nylon gear yet but I expect it's also in good shape. Technically this servicing was unnecessary and just preventative but I'm glad I did it.
 
That's why I would ask anyone looking for a motor if they like to ride more technical and like a motorcycle, or if they just want to turn the throttle and go. If you just want to turn the throttle and cruise a hub motor is the way to go.

I added Permatex multi-purpose synthetic when it was new and again today. I just clean up the dirty grease the best I can with a q-tip and then grease the contact surfaces. There was no migration towards the nylon gear, the gear still had clear grease on the backside of it. The Permatex synthetic is a PTFE based grease but I can say for sure it maintained viscosity and never got thin enough to flow.

I would agree that greasing the motor properly, even when new is a good idea. But I've also seen people actually packing grease into the outboard case which I personally would not recommend. I added a few grams of grease to where they mesh and that's it. When I opened it up today the grease was on the gears and not all over the place and nothing was dry. If people can obtain Mobil 28 then by all means use it. I'm satisfied with the Permatex and the 85g I have will probably last another 10 years.
 
furcifer said:
I don't know of any machine on the planet that can go 50K miles or the equivalent hours without maintenance. It's a totally unrealistic expectation that calls into question other choices or actions you may be undertaking.

That being said, I think I have close to 10K km on my BBSHD and I haven't had the motor open since installing it. I plan on doing it before the weather turns and come October it will be 2 years since I installed this kit. I ran 50A the entire time and actually bumped it up to 60A today (I happened to be on ES today looking at the opensource firmware when I saw this thread). I run the a shunt modded controlled and I make my own gaskets. Zero issues with the motor or controller, but I think the throttle may be going. I leave my bike outside all year round and I ride in the rain.

So I'm basically running double the power through this motor all year round and have had to do zero maintenance on it in 2 years. I've broken a couple cogs and I think the drivetrain is on it's way out. My winter tires are good but my summer tires will be done this season. As an engineer I'm impressed with how durable the BBSHD is operating well over it's rated design.

Grease the motor once every 5000km, check the bearings, the free play in the shafts and gears when you do, and then properly seal it back up and there's no reason you can't get 50k miles out of a BBSHD. I've seen a few people breaking rotor shafts and I'm not sure why that is. I personally suspect user error but it could be a manufacturing flaw. Other than that these motors are bulletproof with very little maintenance.
Click to expand...
" I've seen a few people breaking rotor shafts and I'm not sure why that is. I personally suspect user error but it could be a manufacturing flaw. Other than that these motors are bulletproof with very little maintenance."

The early BBSHD rotors known as A version have a couple design flaws that are all in the same place on the rotor. shaft. The B version has 4 changes made at that location.
The B version also has a bigger shaft and bigger bearing, so the end cover is different too. Usually the whole motor is replaced as a unit. My A version went 4 years of hard street riding, and finally broke testing a very heavy duty chain guide idler setup. This involved wheels up launches in low gear. It actually broke from fatigue cracking under lighter load later on and not while testing the chain guide. The A version has the pinion gear square cut all the way up to the rotor, The B version has a bigger 9mm shaft and a radiused gap between the rotor and the Pinion. The B version would be much preferred for the shunt mod. Just the shaft size =26% more cross section area. The other design changes are to prevent a crack from starting there. The keyway was also cut right up to the pinion providing a notch at the stress riser there for a crack to start.
 
I looked around for the math on the shaft size increase. All of the formulas for motor shafts required torque and load values which are great stuff for actual engineers, but not needed for a simple comparison. I looked up the formula for torsion bars and found what was needed. Using 9mm, and 8mm diameters the formula is 9mm to the 4th power, divided by 8mm to the 4th power. This gives 6561/4096=1.60 or a 60% stiffer shaft.
The exponent of 4 makes sense because the exponent for cross section area is 2, (increased in 2 dimensions) and the exponent for leverage (due to increased radius) is also 2 because it changes leverage (-force), and distance moved (+deformation).
This is the formula used to compare torsion bar sizes for automotive suspensions.
The other design changes will help prevent the start of a crack by gradually distributing the load over a longer section of shaft if you reach the strength limit of the material (which I obviously did) instead of concentrating it all in one area. This can have a huge influence on the durability of the part.
The A rotor is a perfectly good at rated power and normal use. The B rotor is the one you want for hard use, or modifying one of these motors.
The same goes for the white nylon gear. PEEK, or metal parts for modders.
 
Last edited:
Retrorockit said:
" I've seen a few people breaking rotor shafts and I'm not sure why that is. I personally suspect user error but it could be a manufacturing flaw. Other than that these motors are bulletproof with very little maintenance."

The early BBSHD rotors known as A version have a couple design flaws that are all in the same place on the rotor. shaft. The B version has 4 changes made at that location.
The B version also has a bigger shaft and bigger bearing, so the end cover is different too. Usually the whole motor is replaced as a unit. My A version went 4 years of hard street riding, and finally broke testing a very heavy duty chain guide idler setup. This involved wheels up launches in low gear. It actually broke from fatigue cracking under lighter load later on and not while testing the chain guide. The A version has the pinion gear square cut all the way up to the rotor, The B version has a bigger 9mm shaft and a radiused gap between the rotor and the Pinion. The B version would be much preferred for the shunt mod. Just the shaft size =26% more cross section area. The other design changes are to prevent a crack from starting there. The keyway was also cut right up to the pinion providing a notch at the stress riser there for a crack to start.
Click to expand...
We sold hundreds of BBSxx series kits while doing support at California eBike. I've ridden two 36V BBS01a since 2014. The second version BBSHD is a beast. I dumbed mine down and I would expect it to outlive me. Very minor chores like greasing and insuring no moisture ingress is happening and a two wheel conversion ought to get 10's of thousands of miles. The number of pedicabs running the BBSHD is good testament to their reliability. That said, a thoughtful builder and good rider ought to see nearly the same reliability with the 01 and 02 versions.
 
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