Bafang BBS02 uncovered: is it worth the time and effort?

E-bike conversion kits remain popular in 2023, and the Bafang BBS02 is still a favourite amongst DIY electric bike enthusiasts. This comprehensive review examines this popular option’s installation, motor performance, and potential problems. All the information in this Bafang BBS02 review has been gathered from 3 years of experience installing, servicing and test riding.

Skip to product specifications

Key features

• 750w nominal power with 1200w peak power (48v battery)
• Compatible with most frames (BSA threaded bottom bracket)
• Kit includes all mounting accessories
• It can be programmed with an optional USB cable and software.

What’s included in the kit?

The Bafang BBS02B comes as a kit with several accessories and fixings. The contents of the kit may vary between suppliers, as some will add extras like a lockring spanner and a gearshift sensor. Below is a list of what is usually included.

• Bafang BBS02B motor
• Display
• Wiring Harness
• Inner and outer lockrings
• Mounting plate
• Allen bolts and spacers
• Speed sensor and wheel magnet
• Brake cut-off sensors

Installation

The Bafang BBS02B will only fit bicycles that use a BSA threaded bottom bracket. These measure 68 mm-73 mm across the frame and have an internal diameter of approximately 33.5mm. If your bike has a press-fit (see below) or another type of BB, then I would seriously consider a compatible donor bike, as it will make installation a lot more straightforward.

I would not attempt to install the BBS02B on a bike with a press-fit 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.

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 that the steep chainstay angle can prevent the motor axle from fitting in the bottom bracket shell. There’s no easy way around this, and I would stick with 135 mm-142 mm rear hub bikes.

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 press-fit bottom bracket or a beefed-up bottom bracket area. This may make installation very tricky. I wouldn’t advise this and would recommend finding a good aluminium framed donor bike.

The Bafang BBS02 is 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 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.

Motor performance

The Bafang BBS02B 750w offers remarkable performance for the price. I’ve yet to come across one person who isn’t impressed by the level of power on offer. Depending on gearing, it’s possible to reach speeds of over 30 mph on the flat with electric assistance. Hill climbing is its forte – the BBS02 will eat 25% hills for breakfast!

The latest Bafang BBS02B is available in three different configurations: 36v 500w / 48v 500w and 48v 750w. The only difference between these variants is the controller (36v / 48v) and firmware settings. 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.

Bafang Model	Battery	Peak Power (Watts)
BBS02 500w 36v	36v (42.2v x 25A)	1055w
BBS02 500w 48v	48v (54.4v x 18A)	864w
BBS02 500w 52v	52v (58.8v x 18A)	1058w
BBS02 750w 48v	48v (54.4v x 25A)	1200w
BBS02 750w 52v	52v (58.8v x 25A)	1470w

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. Below are some key facts to consider.

• A higher maximum voltage equals a bit more peak power.
• You can 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 the start voltage is higher, the performance drop-off isn’t as noticeable as with a 48v.
• Most of the controller failures I experienced were on bikes fitted with a 52v battery.

I would advise sticking with a 48v battery, which is 54.4v fully charged. I rarely had any issues with the motors that used 48v batteries. If you would 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 well.

Bafang BBS02 common problems

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 may be caused by misuse.

Controller failure

This is one of the most common problems I’ve come across with the BBS02B 750w. It may be accompanied by 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 several 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.

1. 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.
2. 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.
3. 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 constantly without pedalling will lead to problems.
4. Try to avoid water. Although the Bafang is water resistant to a point, it’s not waterproof. Any prolonged immersion in water or using a power wash to clean it is asking for trouble (I know this from personal experience). Even leaving it out in heavy rain can cause problems.
5. 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.

Replacement Bafang controllers are available from Amazon

Speed sensor problems

This is another common fault and is usually easy to rectify. You will likely get a 21 error code. Below, I’ve listed some of the causes of issues with the speed sensor.

1. Faulty or damaged sensor. The sensor is quite vulnerable to knocks and can be easily damaged. Replacements are very cheap and easily available.
2. Bad connection. Check the connector plug, it should be screwed in firmly. Make sure the connector pins are not bent.
3. Misalignment. Make sure the wheel magnet lines up with the arrow on the sensor.
4. The gap between the sensor and magnet. Ideally, the gap should be between 2mm and 5mm; any more or less can cause problems.

Replacement Speed sensors are available from Amazon

Pedal sensor problems

If the pedal assist isn’t working, but the 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.

1. 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.
2. Faulty PAS circuit board. This may be a manufacturing defect like a poor solder. Replacements are very cheap, but you will need soldering skills.
3. Broke PAS sensor magnet ring. It’s another fairly cheap fix, but you will need to disassemble the 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 affect 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 by 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.

Replacement Bafang wiring harness available from Amazon

List of 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 the 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)

Legality

A bike converted to electric using a Bafang BBS02B, may not be legal to use on public roads in some countries. This depends on your local e-bike laws. If you’re not familiar with the 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 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.

Which is the best Bafang display?

When the Bafang BBS02 was first released back in 2015, there were 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 want 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 is 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.

Bafang displays are available from Amazon

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.

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. 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 being 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 off instantly.
• Keep Current (%): This setting reduces the current down to the set percentage of the current PAS level based on your pedalling cadence. You will get 100% at a lower cadence, but as your pedalling rpm increases, the power is backed off to the percentage set (e.g. 70%). I have found that this is set as low as 40% on some motors, 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.

Bafang USB programming cables are available from Amazon

Bafang BBS02 alternatives

For the price, there’s not much out there that can compare with the BBS02 when it comes to the sheer fun factor and versatility. It depends on 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 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.

FAQs

Will the Bafang BBS02 fit any bike?

You can only use the BBS02 on a bike with a 68 mm-73 mm threaded bottom bracket.

Is the Bafang BBS02 waterproof?

It is not 100% waterproof. Riding in the rain is okay, but very heavy rain and deep puddles are best avoided.

How do I choose the right chainring size?

If you are riding off-road, regularly riding up steep hills or towing a trailer, a smaller chainring the better. If you are looking for better top speed, then you will want a larger chainring.

What is the top speed of a Bafang BBS02?

The maximum possible speed will vary depending on your bike’s gearing. Most users report a top-assisted speed of between 28-32 mph.

What battery should I use?

I would personally stick with a 48v, although there are benefits to using a 52v battery.

Can I use a BBS02 conversion off-road?

Yes, the BBS02 is suitable for off-road use, but you will need to watch out for rocks and other potential hazards that could damage the exposed motor.

Does the Bafang BBS02 come with a warranty?

Most re-sellers offer a 12-month warranty with the Bafang BBS02, but warranty claims can often be complicated and not straightforward. This varies greatly between suppliers, and you should always buy from a reputable source (always check customer reviews).

Are mid-drive motors better than hub motors?

No, they have different performance characteristics and may suit certain riding applications better. There are lots of pros and cons of hub motors vs mid-drive motors. It comes down to your budget and needs.

Pros and Cons

Pros

• Great performance
• Smooth and Quiet
• Programmable
• Compatible with most older bikes

Cons

• Installation can be challenging
• Potential long-term reliability issues
• Not road legal in some countries (UK/EU)
• Heavy

Conclusion

Seven years after its launch, the Bafang BBS02B continues to be one of the best e-bike conversion kits available. For the price, there’s nothing to touch it. The nearest competitor is the Tongsheng TSDZ2, and that’s a pussycat in comparison!

You won’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 need that much power?

Despite some reliability problems, Bafang has been constantly making minor tweaks to this motor over the years. It’s possible to get very high mileage from 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 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!

Specifications

• Motor Position: Mid-Mounted (Bottom Bracket)
• Motor Compatibility: 68-73mm BSA Threaded Bottom Bracket
• Rated Motor Power: 500 watts to 750 watts
• Motor Peak Power: 864 watts to 1470 watts
• Max Torque: 120Nm
• Rated Voltage: 36-volt or 48-volt (52v Battery Optional)
• Controller Current: 18-25-amps
• IP Rating: IP65
• Price: $350 – $450

Thanks for reading my Bafang BBS02 review. If you have any questions about 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 an archive of over 300 posts from the last 4-years.