Your BBS02 will give you years of service and love if it is treated properly. The BBS02 loves to eat Watts, but not too many and not too fast. The Pedal Assist system even at its highest setting will only put out around 750 Watts which the BBS02 can eat all day long without overheating or causing problems. The real problems happen when using the throttle at higher power levels.
The throttle on the BBS02 when set to the highest power level can put out more than 1200 Watts. For a tiny fist sized (I have a big fist) motor like the BBS02 that can be just too many watts if used for prolonged periods. The best way to make your BBS02 unhappy is to use too much throttle at too slow of a pedaling cadence speed. The easiest way to tell how fast your motor is spinning is to try to pedal. If the pedaling cadence seems slow then the motor is spinning too slow, if the pedaling cadence is fast, especially if it is too fast to keep up with then the motor speed is fast. Your BBS02 likes to spin fast, especially on steep hills.
Spinning fast puts a lot less strain on every component of the BBS02 drive train system. The easiest way to get the motor to spin faster is to use a smaller chain-ring. For fat-bikes and 29ers that are designed for trail-riding I recommend a 34T or 36T Race Face chainring with a BCD104 chainring adapter. For commuters or trail bikes with smaller diameter wheels you can use the 42T Lekkie chainring which will work even for intermediate trail-riding if you have a large 36T cog granny in the rear. The bigger your chainring is the higher top speed you’ll have, but you are guaranteed to have more problems with the drive unit as everything is under far more load. Using a 52T chainring on a commuter bike will allow you to pedal along comfortably while blasting 35mph+ down the smallest hills, but when going up steep hills you will almost always need to climb in the lowest granny gear to avoid damaging your BBS02.
When coming to a stop make sure to shift into a lower gear as you are coming to a stop. When you start moving again the BBS02 will be much happier that you are in a low gear and will give you more torque, faster acceleration and will produce less strain on the motor.
When you get to prolonged hills that are steep grades it’s important to shift into a low enough gear. The best gear to climb really steep slopes (over 20 percent grade) is the one that spins the motor too fast for you to keep up with pedaling. When you are in this gear then you can safely use the full throttle without risking the motor overheating unless the controller temp is over 130F. If you have the motor spinning slower and are trying to pedal along with the bike then you need to NOT give the motor full throttle or you will likely overheat and blow the mosfets. The controller has a high temp cutout but unfortunately this cutout often does not protect you from blown mosfets. A new controller will run you about $75 and takes about 5 minutes to swap out.
The newer BBS02 750W controllers ship with better mosfets than the older model, but if they are abused they will likely still fail. The easiest way to keep track of your temperature in the controller is to install a $2 aquarium thermometer which takes about 15 minutes and a little silicone. I highly recommend this to all new BBS02 owners, and the BBS02 doesn’t seem to mind much either.
I also recommend installing only one ebrake lever on the left hand side for your front brake. When you are riding singletrack in the woods get in the habit of only using your rear brake. If you touch the front brake you’ll get an annoying 2 second delay before the throttle will work again. When riding on the road with PAS enabled get in the habit of squeezing your front brake when you want to stop, it works better than the rear and you’ll stop a lot faster and the motor will immediately shut off.
If you want to reprogram your controllers you can force your BBS02 to do all kinds of things it was never meant to do. What it also means it that you need to take responsibility for your indiscretion and not go crying back to your vendor when the unit dies. For instructions on teaching your BBS02 new tricks try our Programming Guide.
The primary reduction gear of the BBS02 is built of nylon and can also overheat and ‘peanut butter’. This gear will likely have problems if your chain-ring is too large or if you regularly ride the unit when it is too hot. It costs about $30 to replace the Nylon gear and it takes about 2 hours to do it yourself (unlike the Bosch which you would have to send back to them to fix). I’m sure at some point Bafang will wise up and switch to using composite gears like they did on the Mac motors, but until that happens you’ll need to realize that this gear is one of the main weak points of this design.
The axle of the BBS02 is not tough enough to survive big drops, try to keep your BBS02 within a few feet of the ground, it doesn’t like to fly. The metal casing of your BBS02 is also made of cast aluminum and will not survive repeated bashings on logs. When you approach logs and you’re not sure whether the BBS02 will clear them, come to a stop and gingerly lift your bike over the obstacle. Your BBS02 will thank you for your kindness and consideration and we won’t have to call PETMDU (People for the Ethical Treatment of Mid Drive Units).
When choosing a battery to mate with your BBS02 750W unit make sure that it is at least 48v and the BMS can support 25 Amps continuous output. XT60 or XT90 electrical connectors are recommended but old school Anderson Power Poles also work well at these power levels.
It’s perfectly natural for you to form a bond with your BBS02 drive unit and it is not uncommon to ‘name’ your electric bike and to start treating it like a member of your family. In the wintertime I always bring my bikes inside to keep ice from forming inside the drive unit and the drive-train. Piles of snow or mud on top of the motor can work as an insulator making temps even higher inside the unit. Make sure to keep the top of your unit clean, but don’t wash it with water when it is hot as the metal could get thermally shocked and weaken. Rapidly cooling the unit will also draw moisture inside the unit like a vacuum.
For more instructions on how to get your BBS02 to mate properly with the bike of your choice (68-73mm Bottom Bracket required) look no father than here. If you have a fatbike with 100mm+/- Bottom Bracket then you need a specially modified drive unit or axle kit.
I wrote this article at the request of Eric the owner of electricbike.com and Luna Cycles to include with new BBS02 units he shipped to customers. I am publishing it here because I want everyone to be able to enjoy this article, not just people who purchased a 750W BBS02 from Eric.