ebikechoices is supported by its audience. When you purchase through links on our site, we may earn a commission. Learn more
E-Bike conversion kits are still a very popular choice for going down the route of e-assist. If you have an unloved bike sitting in your shed, then it may be worth converting it using a Bafang BBS02 motor kit. In this review, I’ll tell you everything you need to know about one of the best-selling motors of the last seven years.
The information in this article is based on my own personal experience installing over one hundred of these units during a three year period. I really like the Bafang and it’s an excellent motor. But, like all things electric, there are a multitude of gremlins that rear their head from time to time – in this post I will go over the good, the bad and the ugly!
Who makes Bafang motors?
The motors are made by the Bafang Electric (Suzhou) Co., Ltd. The company was founded in 2003, and has grown to become one of the largest manufacturers of e-bike-specific motors on the planet. Their head office, manufacturing, research and development center is located in Suzhou, near Shanghai.
They employ over 1000 staff globally in eight locations – They have sales and service centres in the USA, Netherlands, Germany, Japan and Taiwan. Also, they have recently opened a factory in Poland primarily for the production of mid-drive motor systems for the EU market.
What’s the difference between the BBS02 and BBS02B
The initial ‘A’ version was launched in 2014 and was plagued by reliability issues. Fast forward to 2016 and the ‘B’ model was introduced with an updated controller, improved water resistance and reworked internals. The Bafang has undergone more tweaks since then, and it can be safe to say that any Bafang purchased from an authorised supplier will be the latest model. The ‘A’ model was discontinued years ago.
How does a Bafang motor work?
The Bafang BBS02B works like any other electric motor by converting electrical energy into mechanical energy. This energy is transferred through the bikes drivetrain to the real wheel, and provides an additional boost on top of rider pedalling input. The electric assist on the BBS02B can be activated by pedalling, or independently through a thumb throttle.
What’s the difference between the BBS01 and BBS02?
The Bafang BBS02B has a wider stator and the controller is different. The BBS02B can be used with a 48v battery, whereas the BBS01B is only designed for 36v. Basically, the BBS01 is more suited to urban or commuting applications where pedal assist is mainly used, and the terrain is moderate. Plus, in the EU, UK and Australia where e-bike laws are more restrictive (than the US). The BBS02 is much better suited to more rigorous applications like riding off-road and climbing very steep hills.
Are all BBS02B motors the same?
The only difference between the models are the controller (36v / 48v) and firmware settings. There are currently three different versions usually available, although 250w and 350w versions are also available from some suppliers.
|BBS02 500w 36v||36v (42.2v x 25A)||1055w|
|BBS02 500w 48v||48v (54.4v x 18A)||864w|
|BBS02 500w 48v||52v (58.8v x 18A)||1058w|
|BBS02 750w 48v||48v (54.4v x 25A)||1200w|
|BBS02 750w 48v||52v (58.8v x 25A)||1470w|
The voltage figures in brackets are for a fully-charged battery. Note: As the voltage drops, so will the power.
The latest Bafang BBS02B is available in three different configurations: 36v 500w / 48v 500w and 48v 750w. The 750w version is the most popular as it offers the most bang for your buck! The motor itself is physically the same as the lower powered BBS01 250w / 350w, the only difference being the internals and controller.
Will the Bafang BBS02B fit any bike?
The Bafang BBS02B will only fit bicycles that use a BSA threaded bottom bracket. These measure 68mm-73mm across the frame and have an internal diameter of approximately 33.5mm. If your bike has a pressfit (see below) or other type of BB, then I would seriously consider a compatible donor bike, as it will make installation a lot more straightforward.
Pressfit bottom bracket
As I have said above, I would personally not try to install the BBS02B on a bike with a pressfit bottom bracket. Although, in some cases this may be possible with a bit of ingenuity. A normal reducer shim may not be sufficient as it’s unlikely there would be enough clearance between the motor axle and housing (to clear the BB shell). You would need to machine an eccentric shim for this to be possible.
Boost rear hub spacing
Lots of modern mountain bikes (and some adventure bikes) have boost rear hub spacing (148mm) to accommodate the wider tyres commonly used. The problem with this, is the steep angle of the chainstay can prevent the motor axle from fitting in the bottom bracket shell. There’s no easy way around this, and I would stick with 135mm-142mm rear hub bikes.
Carbon fibre frames
I have installed both the BBS02 and BBSHD on carbon fibre frames before without any long-term issues. But, most modern carbon bikes have a pressfit bottom bracket, or a beefed-up bottom bracket area. This may make installation very tricky. Personally, I wouldn’t advise this and would recommend finding a good aluminium framed donor bike.
Is the BBS02 easy to install?
It’s straightforward enough to install if you have the right tools and you’re comfortable working on a bicycle. The hardest part would be to remove the bottom bracket bearing. On older bikes, this can be very hard and you will definitely want a long breaker bar (and a lot of patience).
Once the bottom bracket has been removed, you should thoroughly clean the area, ready for fitting the motor shaft. Providing your bike is compatible, this should be fairly straightforward. You may need to remove the cable guide (if you have one) underneath the BB shell, as this might interfere with motor fitment. Also, in some cases, you may need to file down any burrs where the frame tubes meet the BB shell (internally).
When the motor is in place and the lockrings tightened, then it’s just a case of fitting the display, speed sensor, battery and brake sensors (if needed). Finally, tidying up the excess cabling can take a bit of time, but it’s worth doing to give a professional finish to your e-bike.
For more information on the process, I have included a Bafang BBS02 installation manual in my resources section.
- Weight: 4.6kg
- Top Speed: 28 mph +
- Wheel diameter: 16″ / 20″ / 24″ / 26″ / 27.5″ / 28″ supported
- Power output: 750w continuous
- Voltage: 48v
- Current: 25A
- Torque: 120Nm
- IP rating: IP65
Is the BBS02B legal?
This depends on your country’s local e-bike laws. If you’re not familiar with e-bike law in your country, it’s advisable to check beforehand. In the US, federal law allows for 750w e-bikes. But, in the UK, EU and Australia the maximum continuous power is limited to 250w (peak power can be higher, but it’s the continuous rating that’s important).
A Bafang BBS02B 750w is rated to 750w continuous, with a peak power output of up to 1470w (with a 52v battery fitted). If you are in the UK and planning on using this on private land, that is absolutely fine, but if you are going to use it on public roads then you should be aware of the potential legal implications first. Please read my article on UK/EU electric bike law.
Are Bafang motors reliable?
Bafang motors are generally reliable. But, like any mass-produced electrical item, problems do occur from time to time. I have done Bafang conversions which are still going strong after 4 years and over 5000 miles. The flip side to that, is I’ve also had a fair share of issues.
Below I have listed some of the common faults experienced with the Bafang BBS02 over the last few years. Some of these problems seem to be the result of random manufacturing defects and others maybe caused by misuse.
This is one of the most common problems I’ve come across with the BBS02B 750w. It may be accompanied with an error code (see below). Sometimes the motor will stop working but will still switch on. If you grab the rear wheel and spin it backwards, if there’s significant resistance, this can indicate a blown controller.
Controller failure can happen for a number of reasons and there are things you can do to prevent this from happening. In some instances, there may be a manufacturing defect which has been missed by quality control.
- Never pull away in top gear whilst in full power mode. You should always select a lower power setting, and be in the lowest gear. Treat the same as you would a motorcycle or car and always select a low gear for pulling away.
- Modify controller settings. You can dial back the start current and maximum peak current. I had mine set to 18A with a lower start current and never had a single problem in over 2000 miles of use.
- Don’t use a throttle. A throttle is okay to use when you’re already riding along at a few miles an hour. But, treating it like an electric moped and using the throttle all the time without pedalling will lead to problems.
- Try and avoid water. Although the Bafang is water resistant to a point, it’s definitely not waterproof. Any prolonged immersion in water or using a power wash to clean it, is asking for trouble (in know this from personal experience). Even leaving it out in heavy rain can cause problems.
- Stick with a 48v battery. Fitting a 52v battery does have its benefits. But, most of the controller failures I’ve dealt with were on bikes fitted with a 52v battery.
Speed sensor problems
This is another common fault and is usually easy to rectify. It’s likely you will get a 21 error code. Below, I’ve listed some of the causes of issues with the speed sensor.
- Faulty or damaged sensor. The sensor is quite vulnerable to knocks and can be easily damaged. Replacements are very cheap and easily available.
- Bad connection. Check the connector plug, it should be screwed in firmly. Make sure the connector pins are not bent.
- Misalignment. Make sure the wheel magnet lines up with the arrow on the sensor.
- Gap between sensor and magnet. Ideally, the gap needs to be between 2mm and 5mm, any more or less can cause problems.
Pedal sensor problems
If the pedal assist isn’t working but throttle is working fine, then that points to a problem with the pedal assist circuit. Unfortunately as the PAS sensor is internal, it usually requires motor disassembly to fix. I have listed some of the possible causes below.
- Controller connector plug. Sometimes the plug that connects the controller to the PAS circuit is not properly connected. You will need to remove the controller and check the connection, and connector pins.
- Faulty PAS circuit board. This may be a manufacturing defect like a poor solder. Replacements are very cheap, but you will need soldering skills.
- Broke PAS sensor magnet ring. Another fairly cheap fix, but you will need to disassemble to motor to do the job.
Hall sensor problems
A hall sensor provides rotor position feedback to the controller. If one or more hall sensors become defective, then it will effect the running of your motor. You may get an error code 08 on your display, and it is usually accompanied by a loss of power and a grumbling sound.
You will need to disassemble the motor to visually inspect the sensors. Sometimes a poor solder can cause the problem, or they can just fail. Either way, you will need to be a competent solderer to repair yourself. The sensors themselves are very cheap and easy to get.
Wiring harness problems
This problem is often accompanied with an error code 30, and can be caused by a poor connection, damaged wiring harness or bent connector pins. It may result in complete loss of power or the malfunction of other components like the display or speed sensor.
Bafang Error Codes
- 05 Throttle abnormality
- 06 Low voltage protection
- 07 High voltage protection
- 08 Hall sensor abnormality
- 09 Phase line abnormality
- 10 Controller overheating
- 11 Temperature sensor abnormality (in controller)
- 12 Current sensor abnormality
- 13 Stator overheating
- 14 Temperature sensor abnormality (in motor)
- 21 Speed sensor abnormality
- 22 Communication abnormality in BMS (battery management system)
- 23 Front light abnormality
- 24 Front light sensor abnormality
- 30 Communication in system abnormality (wiring harness or connections)
Can you use a 52v battery with the BBS02B?
You can use a 52v battery with the Bafang BBS02B. But, there are pros and cons to going down this route. A 52v battery when fully charged is at 58.8v, this is very close to the motor controller’s maximum operating voltage of 60v.
Positives of 52v battery
- Higher maximum voltage equals and bit more peak power.
- You could achieve the same power as a 48v battery but with a low current (amps). This is what I did with my Bafang conversion and I had over 2000 miles of trouble-free use.
- Because start voltage is higher, the performance drop-off isn’t as noticeable as with a 48v.
Negatives of 52v battery
- Most of the controller failures I experienced were on bikes fitted with a 52v battery.
I would personally advise sticking with a 48v battery which is 54.4v fully charged. I very rarely had any issues with the motors that used 48v batteries. If you would still prefer to fit a 52v battery, then I would lower the peak current to 22A. I had mine at 18A and it still went very in full power mode!
BBS02 vs Bosch
If you have been trying to decide whether to go down the route of conversion vs buying an electric bike, then you’ve probably come across the Bosch motor. Although there are similarities between the BBS02 and Bosch motor, they are two very different systems. Below, I have listed some of the pros and cons of the Bosch motor.
- Bosch has torque-sensing pedal assist. Very smooth and intuitive – reacts to your pedalling input and gives you the best riding experience possible.
- Very efficient. Because of the motor design and torque-sensing assist, the Bosch motor will give you a much greater potential battery range.
- Lightweight. The latest Bosch motor range is incredibly lightweight – 2.8kg vs 4.6kg for the Bafang.
- Good reliability. Although the Bosch isn’t immune to faults and problems, general reliability is much better than the Bafang. It’s not uncommon to here of owners getting tens of thousands of miles use from their Bosch e-bikes.
- Warranty. If you buy your Bosch e-bike new from an authorised dealer, you will have a two year warranty. Plus, there are an increasing number of companies who can repair your Bosch motor outside of the warranty.
- Legal. Unlike the Bafang BBS02, the Bosch e-bike motor is compliant with EU and UK e-bike laws. This may be a good or bad thing depending how you feel about the current laws. Bosch motors can be unrestricted, but this invalidates the warranty and any modification is stored on the controller firmware.
- Expensive. The initial purchase cost of a Bosch e-bike is likely to be over £2000 / $2000. Plus, the higher performance CX motor isn’t usually available on e-bikes under £2800.
- Not for the DIY enthusiast. Bosch e-bike motors and batteries are locked in.It’s hard to get parts, and Bosch will not sell parts to private customers (only registered dealers). You will need to take to a dealer to get diagnostics.
- Difficult to fix if they go wrong. If a motor does go wrong outside of the warranty, good luck in fixing it yourself! You will need to either replace the motor completely or go to a repair specialist as parts are notoriously hard to get hold of.
- Limited performance. Because the Bosch is a road legal system, the top speed is limited to 15.5 mph (25 km/h) in the EU and UK. The Bafang on the other hand has a top speed of over 28 mph with the right gearing.
As you can see, there are lots of positives and negatives to owning a Bosch e-bike. I would say if you’re a ‘hands on’ kind of person and you like to tinker and change things, then the Bosch isn’t for you and a Bafang would be a much better option. You could keep a Bafang going indefinitely – spare parts are easy to procure and affordable. Plus, any competent DIY enthusiast can work on a Bafang motor.
If, on the other hand you just want a reliable e-bike you can just get on and ride without having to get your hands dirty. Then I would say a Bosch or similar would be your best bet.
What is the best Bafang display?
When the Bafang BBS02 was first released back in 2015, there was only a couple of displays to choose from. Nowadays you are spoiled for choice. Below, I have listed the 5 best Bafang displays suitable for the BBS02B.
- P850C This colour 3.2″ display has been around for a few years now, but has continued to be a popular option. It has great functionality and is one of the more affordable options.
- 500c If you want a smaller display that can be mounted near the left hand grip, the 500c ticks all the right boxes. It has most of the functionality of the P850c, but in a more compact size.
- SW102 The smallest of the available Bafang displays is ideal for riders who wants a very small but functional display.
- DP-C18 This display is made by Bafang and is used on a lot of factory e-bikes. It’s the most expensive of the bunch, but is very high quality and has added functionality.
- C965 The oldest of the displays here. The C965 has been around since the beginning (2015) and is still quite popular due to its simplicity and minimalist design.
Programming the Bafang BBS02
One of the great things about the BBS02 is the ease by which it can be programmed. This doesn’t mean programming in the classic sense, more like re-configuring the controller parameters to better suit your needs and environment. Most e-bike controllers can be re-programmed, but none are as straightforward as the Bafang.
What do you need?
It doesn’t cost a lot of money to get started. You’ll need a laptop or desktop PC, a USB programming lead and a copy of the free Bafang config tool.
What parameters can you change?
I won’t go into too much detail here as there’s enough info for a separate article. I’ll just cover the basics of what can be done.
- Low Battery Protect (volts): This can be changed if you’re using a 52v battery. It shouldn’t be set too low as although the battery BMS will override this, it’s not worth risking over discharging the battery and potentially damaging the cells.
- Limited Current (amps): On a stock motor this is usually set to 25 amps and cannot be raised any higher. I usually lower this to 18A, which will reduce the peak power, but can improve controller reliability.
- Start Current (%): You should either leave this alone or lower it slightly. If set too high, you run the risk of blowing the controller. Setting this lower is great for a smoother start up and particularly good if you’re using an internally geared hub.
- Slow Start Mode (1-8): This setting determines how quickly the power ramps up on start-up. I would leave this, as set too low can potentially blow the controller and too high results in a jerky pedal assist (when starting pedalling).
- Time of Stop (x10ms): This determines how quickly the motor shuts off after pedalling stops. I sometimes find out of the box, this is set too high (25ms), I usually reduce this to 10ms which means the motor shuts of instantly.
- Keep Current (%): This setting reduces the current down to the set percentage of the current PAS level based on your pedalling cadence. At a lower cadence you will get 100% but as you pedalling rpm increases the power is backed off to the percentage set (e.g.70%). I have found on some motors this is set as low as 40% which is way too low. I usually set this to 70%.
You can also set pedal assist speed and current for each possible assist level (up to nine). Plus, there are many more settings you can change. For more information, I can highly recommend the electricbike-blog for the most in-depth Bafang programming guide online.
Riding a Bafang BBS02B powered Electric Bike
The first time you ride a Bafang BBS02 powered e-bike, is going to be a memorable experience. This motor will transform your humble bicycle into a high performance e-bike.
For me it was the beginning of a long journey back to fitness, and it ultimately helped me rediscover my love of cycling. At the time, I was out of shape and was really struggling with my fitness. My Bafang-converted Ridgeback hybrid gave me a new lease of life. After that first ride I was hooked! In the months that followed, I was out on it most days and it gave me the confidence to tackle more challenging routes with steeper hills.
After nearly a year and over 2000 miles of regular riding, I made the transition to a regular bike and haven’t looked back since. But, the Bafang BBS02 isn’t just a great motivational tool – it’s a great motor for day to day riding and especially commuting. To maintain 20 mph+ on a regular bike requires a certain degree of fitness. And, if you want to get to work in good time without turning up in pools of sweat, the Bafang is an ideal solution. Plus, you’ll save a packet on fuel.
Bafang BBS02 alternatives
For the price, there’s not much out there that can compare with the BBS02 when it comes to sheer fun factor and versatility. It really depends what you’re looking for in an e-bike motor.
If you want an electric bike system that’s going to take you up the steepest hill, and push you along at a swift pace without fuss, then the BBS02 is for you. If, however you want a motor that’s going to amplify your own effort and give you a bit of a workout at the same time. Then the Tongsheng TSDZ2 is going to be a better option. Read the BBS02 vs TSDZ2 comparison article.
If you need a motor for real heavy-duty applications like carrying cargo or trailers, then it would be worth paying the extra and buying a BBSHD. It’s a real beast of a motor and is reliable to boot! More reliability, robust internals and bags of torque. Read my BBS02 vs BBSHD article.
Seven years after its launch, the Bafang BBS02B continues to be one of the best selling e-bike conversion kits globally. For the price, there’s nothing to touch it really. The nearest competitor is the Tongsheng TSDZ2, and that’s a pussycat in comparison!
You just can’t find this much torque, power and versatility in any other conversion kit for the price. Sure, if you can stump up an extra couple of hundred, then I’d seriously consider the BBSHD. But, do you really need that much power?
Despite some reliability problems, Bafang have been constantly making minor tweaks to this motor over the years. It’s possible to get very high mileages out of the BBS02 with sensible use and periodic maintenance.
Apart from some of the electrical issues, my only other complaint would be the pedal assist. This can be fine-tuned using the software, but out of the box, it can have a very on/off feel to it. It’s a real shame Bafang didn’t make an upgraded version with a torque-sensor as that would have taken the BBS02 to another level. To date, this feature is only available on their ‘M’ models which require a special frame for fitment.
All in all, I still love the Bafang BBS02, and in 2022 / 2023 it’s still one of the best e-bike conversion options available and highly recommended!
Bafang BBS02B Pros and Cons
- Great performance – best bang for your buck!
- Smooth and quiet motor
- Plug and play
- Good parts availability
- Easy to service and maintain
- Performance can be fine-tuned using the optional USB lead and software
- PAS has a very on/off feel to it
- Controller failure
- Not 100% waterproof
- Increased wear on drivetrain
- Limited compatability – will only fit 68-73mm BSA bottom brakets
- Not road legal in some countries
Where to buy the Bafang BBS02B
The Bafang BBS02B 750w is the best selling mid-drive e-bike conversion kit in the world, and is easily available in most countries. The cheapest place to buy is usually Aliexpress. Although, some people find the returns process can be difficult. If you’re concerned about potential problems and want peace of mind, then I’d be inclined to try Amazon or eBay. You will pay more, but returning a faulty motor is usually more straightforward. Below I’ve provided links to the Bafang motor sellers with good feedback in most regions.
Thanks for reading my Bafang BBS02 review. If you have any questions relating to the Bafang motor, please feel free to leave a message in the comments section below. Or head on over to my BBS02 Forum, where there’s over 300 posts from the last 4 years.