Bafang Motors - the best and the worst

[AHicks]

Nothing to back me but logic. If you've taken out 3 BBSHD motors already, it's pretty clear to me you are doing something wrong. Could be all sorts of things, including your expectations. If you think adapting an Ultra to fit, with no other changes, is going to fix this issue, my bet is you're going to be looking at a 4th disappointment......

Clearly, it's time to take a breather and figure out what you are doing wrong.

Running a 52t gear, it sounds like you're trying to go fast. Maybe you should be looking at a direct drive hub? They're ability to get rid of internal heat makes them MUCH better suited to high speeds than a mid drive or gear driven hub. My opinion anyway.... -Al

 

[theemartymac]

so you suggest I can’t use a 52t front cog? Not even on the ultra?

A 52T on a hub with hills is definitely asking for excess heat buildup. The Ultra could handle it better if you actually use the gears a little.

Always remember that any input power not delivered as RPM is converted to heat. Any time the motor has to push hard (Accelerate/climb) as opposed to cruise (constant speed) it is converting some power to heat. That 52T will work to your advantage once you're up to high speed on the flat, but it's going to seriously hurt efficiency on any hills or stop and go scenarios. I plan to swap out a 50 or 52 on my Ultra bike, but that bike is used primarily for highspeed commuting and long distance rail-to-trail rides above 25kph. My hub bike will keep it's 42T as I have no doubt I would shorten the life of it by trying to squeeze out the extra speed between our hills here.

 

[Mike_V]

[ That's his sales technique ]
so you suggest I can’t use a 52t front cog? Not even on the ultra?

 

[TForan]

I have a 52T on my Ultra and it has worked out so far. With the stock 44, I was always in top gear . That said, I might drop it back to a 48 or 50.

 

[tomjasz]

Not even on the ultra?

I apologize, I can't answer that. I've not done any work on that motor and haven't been following those that have. Doug at California eBike has started acquiring and selling ultra parts. I defer any questions to an employee in California.

 

[Reece123]

can you do that? I thought newer generation Bosch motors will detect a chip and brick the motor/controller?

I’m not sure, they guy at the shop said it could be done, I’ve done it with an evo motor, that i also burnt out 3 of those dodgy motors, motors seem to fail on every bike I ride, yes must be really bad luck or they just can’t take the 50km rides I do daily, I thought that’s what bikes were for, to ride as a form of alternative car transport, but don’t seem up for the task except pedalling to the shops and back

 

[AHicks]

Pretty sure you are going to continue your streak of fried motors until you start giving internal heat build up more of a priority. Gear driven motors buried inside a housing, makes no difference if that's a hub or a mid drive design, can't dissipate enough heat quickly enough to maintain speed of any kind for more than a few minutes....

 

[Reece123]

@TForan Thanks for your feedback, can I ask how many kms or miles have you done using the 52t on your ultra motor? Why are you thinking of dropping back?

 

[Reece123]

Pretty sure you are going to continue your streak of fried motors until you start giving internal heat build up more of a priority. Gear driven motors buried inside a housing, makes no difference if that's a hub or a mid drive design, can't dissipate enough heat quickly enough to maintain speed of any kind for more than a few minutes....

Are you suggesting the 52t cog then is also too large? What is the largest you would recommend and how do I best manage to maintain pedalling motion at higher speeds?

 

[Gionnirocket]

Are you suggesting the 52t cog then is also too large? What is the largest you would recommend and how do I best manage to maintain pedalling motion at higher speeds?

52t is too large if you aren't helping out a bit. Are you riding it as an ebike or a moped? An ebike it is designed to assist you with power, not be the sole source. I easily reach 25+mph using a 44t with13t-28t in the rear with a BBS02B. If you are mashing for high speed and in high gear without pedaling you will continue to fry what ever you ride.

 

[Reece123]

52t is too large if you aren't helping out a bit. Are you riding it as an ebike or a moped? An ebike it is designed to assist you with power, not be the sole source. I easily reach 25+mph using a 44t with13t-28t in the rear with a BBS02B. If you are mashing for high speed and in high gear without pedaling you will continue to fry what ever you ride.

I hardly ever used the throttle, I peddled as much as I could, to assit the motor and get as much distance as possible.... I was used to cruising on flat bike paths at about 30mph, maybe I need to lower my expectations with speed, yet you see many videos with the same motor going much faster than that, some even peddling

 

[Gionnirocket]

I hardly ever used the throttle, I peddled as much as I could, to assit the motor and get as much distance as possible.... I was used to cruising on flat bike paths at about 30mph, maybe I need to lower my expectations with speed, yet you see many videos with the same motor going much faster than that, some even peddling

I don't think your top speed is the issue. With a 46t in the front I can easily do 30mph and with the motor drawing 10 amps. I think it might have to do more with how aggressively you reach 30mph and in what gear ratio. Are you using your full compliment of rear gears?

 

[Reece123]

I don't think your top speed is the issue. With a 46t in the front I can easily do 30mph and with the motor drawing 10 amps. I think it might have to do more with how aggressively you reach 30mph and in what gear ratio. Are you using your full compliment of rear gears?

How many gears do you need? Ive usually used a 10 speed with a rear cog of 11 to 36t. I note some are suggesting using a 3 speed internal rear hubs for example, which seems like a good idea, are less gears better? but I’m concerned the motor would just chew through that as well.

So what’s the ideal safest set up with an ultra motor to get the best top speed with usually using pedal assist?

 

[Gionnirocket]

How many gears do you need? Ive usually used a 10 speed with a rear cog of 11 to 36t. I note some are suggesting using a 3 speed internal rear hubs for example, which seems like a good idea, are less gears better? but I’m concerned the motor would just chew through that as well.

So what’s the ideal safest set up with an ultra motor to get the best top speed with usually using pedal assist?

It sounds like you are doing it more than well enough.. and I only have experience with the BBS02B which is less powerful than both the BBSHD and Ultra.
I don't know why you are burning through motors... The HD should be more than capable.

 

[AHicks]

I hardly ever used the throttle, I peddled as much as I could, to assit the motor and get as much distance as possible.... I was used to cruising on flat bike paths at about 30mph, maybe I need to lower my expectations with speed, yet you see many videos with the same motor going much faster than that, some even peddling

It's about not getting that motor hot to the point you smoke it. I'm sure you've seen the Ultra's doing 30mph or more, but generally that's a sprint, not 50km. You can get it hot, but you need to let it cool afterward.

It's about how many watts you are pulling. You need to figure out what size gear you need/use while monitoring that number. Max gear size will be all over the ball park. Examples of some factors will be your weight, your size, tire size (fatty vs. road tire for instance), tire inflation, head wind for that particular day, etc.

Your 52t may be fine for occasional use if you drop back to a lower gear in back the rest of the time.

I can't give you a max wattage that's guaranteed not to smoke your motor. I generally don't ride much over 15mph tops, and my butt's only good for 20 miles max, so no idea of the maximum I can get away with for the distance you're running. I can tell you that your idea of dropping your speed expectations for a long ride like that is probably a real good idea. Another one might be to get off the bike and feel the motor to see if it feels hot.

Last, my understanding is there's a thermal switch buried in the windings of the Ultra, designed to shut the motor down prior to it destroying itself. Having that happen once or twice should be cause for an immediate change of riding habits....

 

[TForan]

@TForan Thanks for your feedback, can I ask how many kms or miles have you done using the 52t on your ultra motor? Why are you thinking of dropping back?

With the stock chainring, I was in top gear all the time. Now, I 'm able to use about five gears but it just seems a little too much. I would recommend a 48T.

 

[FlatSix911]

Mid drive? Rear hub? What price range.

I can only speak to their mid drives (no experience with their hub drives but they are fairly well regarded). The best IMO would be the Bafang Ultra with aftermarket X1 controller (offered by Watt Wagons). The worst? I'm not sure there are any bad motors. The BBSXX have decent power. The BBS01 and BBS02 are very quiet. But none of he BBSXX have torque sensing. The M600 and Ultra have torque sensing but not the smoothest power delivery. The M600 can't be programmed by the user and is loud unless you opt for aftermarket nylon reduction gear. The reason to go with a Bafang mid drive is if you want more power than the euro spec mid-drive offerings.

Good to know.
Does anyone have an opinion on the Bafang M800 mid-drive that is designed as a fast/light 28mph motor?
I am looking at a road bike with this drive system for light assist on climbs and would like feedback on M800.

 

[Reece123]

It's about not getting that motor hot to the point you smoke it. I'm sure you've seen the Ultra's doing 30mph or more, but generally that's a sprint, not 50km. You can get it hot, but you need to let it cool afterward.

It's about how many watts you are pulling. You need to figure out what size gear you need/use while monitoring that number. Max gear size will be all over the ball park. Examples of some factors will be your weight, your size, tire size (fatty vs. road tire for instance), tire inflation, head wind for that particular day, etc.

Your 52t may be fine for occasional use if you drop back to a lower gear in back the rest of the time.

I can't give you a max wattage that's guaranteed not to smoke your motor. I generally don't ride much over 15mph tops, and my butt's only good for 20 miles max, so no idea of the maximum I can get away with for the distance you're running. I can tell you that your idea of dropping your speed expectations for a long ride like that is probably a real good idea. Another one might be to get off the bike and feel the motor to see if it feels hot.

Last, my understanding is there's a thermal switch buried in the windings of the Ultra, designed to shut the motor down prior to it destroying itself. Having that happen once or twice should be cause for an immediate change of riding habits....

I usually do 15 miles to work, then 7 hour brake, then 15 miles home, largely on flat ground, though often against a head wind and can get hot where I live, on 47 700cc tires. If the ultra is designed to shut down if it heats up that would obviously help me, then I go to a 48t front cog might be a plan, be it somewhat further expense. (ps plu I also cracked my bike frame just under the seat post because I had it too high and a seat suspen post with a backward pushing spring system forcing the seat post backwards not helping matters, I’ve had a terrible run of bad luck!) I love ridimg so much I don’t won’t to let it beat me, but one more series set of failures could be the death nail.

 

[ElevenAD]

Reece123?

well there's yur problem right there!

 

[Reece123]

Reece123?
View attachment 77211
well there's yur problem right there!

Haha, I wish, then I wouldn’t need a motor