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In this Bafang BBS01 250w review, I will be going over the pros and cons of this popular mid-drive conversion kit – this is the only variant I can recommend for road legal use in the UK, EU and Australia. The more powerful variants of the Bafang motor are covered in separate articles.
The Bafang BBS01 has been with us for a few years now and continues to be popular with DIY e-bike builders the world over. It’s particularly popular in the UK and EU countries, where e-bike laws are more restrictive (than in the US). I have personal experience installing dozens of these motors over 5 years, and I still think it’s one of the best road-legal options for converting your bike to electric assist.
Bafang BBS01B Specs
|Motor Position||Mid-Mounted (Bottom Bracket)|
|Motor Compatibility||68-73mm BSA Threaded Bottom Bracket|
|Rated Motor Power||250-watts to 350-watts|
|Motor Peak Power||540-watts to 648-watts|
|Motor Rated Voltage||36-volt|
|Motor Weight||3.8 kg|
|Price||$350 – $450|
|Availability||Various online retailers|
- Road legal in the UK and EU (if the speed limit is set)
- Plus and play design
- Very smooth and quiet
- Can be programmed (with optional USB lead)
- Good parts availability – easily serviceable
- Lacks the ‘get up and go’ of the more powerful variants
- Only compatible with 68-73mm bottom brackets
- Controllers can be unreliable
- Not completely waterproof
Bafang is currently the global leader in plug-and-play mid-drive electric bike conversion kits and has been for several years. Earlier versions were plagued by reliability issues, and although these can still be an issue, the problem isn’t as bad as it was four or five years ago.
I have personally installed over a hundred of these kits on various bikes, ranging from low-step commuter bikes to full-suspension mountain bikes.
The main criterion for installation is the size of the bike’s bottom bracket. It needs to be a standard 68 mm-73 mm wide bottom bracket with an inside diameter of approximately 33.5mm. It must be noted that these kits are not intended to be installed on bikes that use a pressed-fit bottom bracket, as the dimensions are not compatible with the motor unit. There can be a way around this if a special shim and mounting plate are machined by a professional engineer.
If your bike has an eccentric bottom bracket as fitted to tandems and bikes with internally geared hubs like the Shimano Nexus, installation is still possible but may be problematic.
What’s included in the Bafang BBS01B 250w Kit?
- The motor unit with integrated controller
- LCD Display
- Wiring loom
- Inner and outer lock-nuts
- Chainguard (BBS01 and BBS02)
- Thumb throttle – I do not recommend fitting this, as it is unnecessary and will increase the risk of controller failure if used inappropriately.
- Brake levers with cut-off sensors (only compatible with cable brakes)
- Speed sensor and wheel magnet
- A bag of various Allen bolts and screws
Is the Bafang BBS01B 250w Legal to Ride in the UK and EU?
Unlike the Bafang BBS02B 750w, the 250w version would be perfectly legal to use in the UK, EU (and Australia). But, you will need to check the speed limit is configured out of the box to no more than 25km/h (15.5mph). Some sellers in the UK and EU do this by default, but you will need to check beforehand if you’re concerned about legality.
Most displays have an advanced settings menu which can be accessed via a 4-digit pin code. It is possible to alter the speed limit, but this would render your bike illegal to use – Please consider the laws in your country before changing the speed limit.
Is the Bafang BBS01B Easy to Install?
If you’re looking for a nice and easy conversion to do yourself, but you have little or no experience with bicycle mechanics or using tools, I would recommend getting a friend or bike shop to help with the installation.
Certain aspects of installing the BBS01B can be challenging and it’ll help if you are mechanically minded. See my guide on how to install a Bafang BBS02 This also covers the BBS01 which is physically the same. The installation will need to be carried out by someone who is fairly competent. Removing the bottom bracket can be a right pain, and you will require a lot of patience!
Motor Technical Data
These motors have an internal cadence sensor, and give assist based on pedalling cadence. The controller will reduce the power at any given power level based on pedalling rpm. This is called the keep current, and depending on the way your particular controller is programmed, this can reduce the power by up to 60%. The logic behind this is the higher the cadence, the less help you need, this is somewhat counter-intuitive as electric motors work best when spinning at a high rpm.
One great thing about these motors is they can be programmed with a Bafang programming cable and software (which you can download for free here). I will be writing a separate post about programming the Bafang. PLEASE NOTE: Reprogramming the 250w motor to any higher than 15A and 15.5mph (25km/h) would make it illegal for road use in the UK / EU / AU.
The motor itself works through a series of gears and drives the rear wheel directly through a single front chainring. The benefit of this is the motor is using the bike’s gear ratios for maximum efficiency and torque. The downside of this is you have to make sure you are in the right gear when hill climbing as excess load on the motor can cause controller failure.
The 250w motor is very quiet and smooth, and you have up to 9 levels of pedal assist to choose from.
Is the Bafang BBS01B 250w reliable?
As with all things electric, problems can and do occur from time to time. I have installed many BBS01B 250w Bafang motors and to date, have only had a handful of issues reported – these are mainly confined to the more powerful variants. Having said that there are several things to consider.
- Controller failure is rare on this model nowadays, especially since Bafang upgraded the MOSFETs in the controller.
- You will need a Bafang lock-ring spanner – these motors do sometimes need to be re-tightened periodically.
- The speed sensor can be easily knocked out of alignment with the wheel magnet – this will throw up an error code and the pedal assist will stop working.
- In my experience, the C965 display is the most reliable but has limited functionality. The available colour displays are great but I have had the occasional fault with these in the past.
- Increased wear and tear on the bike chain and gear components – this can be mitigated by fitting a Bafang gearshift sensor.
Riding a Bafang-Powered Electric Bike
The 250w motor is very quiet and smooth, and you have up to 9 levels of pedal assist to choose from, so you really can fine-tune the power output to suit your needs. When climbing steep hills you will need to make sure you are in a low gear (as you would be in a car or on a motorcycle) this is especially important as trying to climb a hill in a high gear will put the motor under excess load and could overheat, causing controller failure.
The pedal assist is responsive, and works well, although, on some of the older units, there was always a slight over-run noticeable when pedalling stopped. This was down to one of the controller programming parameters being set too high. I always reprogrammed the unit to stop this issue.
The main downside, in my opinion is the extra pedalling resistance this motor has when the power is on ‘0’ or the motor is switched off altogether. It is not too bad on the flat, but it is noticeable when going up a slight gradient. This is the main reason, I tend to prefer small geared hub motors.
If your bike has a double or triple front chainset, then you will be sacrificing that for a single steel chainring. Bafang only offers 44t, 46t and 48t options. This in my opinion is high gearing, especially if you are climbing lots of steep hills. There are however a couple of alternatives – you could fit a 104BCD chainring adaptor or buy one of the many aftermarket chainrings available.
If you want to fit the brake levers with cut-off sensors, then bare in mind these are only suitable for cable-operated brakes. If your bike has hydraulic brakes, you may want to purchase hydraulic brake cut-off sensors or completely new hydraulic brakes with the sensors already built in.
The Bafang mid-drive motor is not for everyone. Installation can be challenging and the motor will need periodic maintenance. It is nonetheless an excellent option, and the result will be a bike that looks more like a factory-produced e-bike.
For a 250w motor it produces a lot of torque, I have done a side-by-side hill climb comparison of the Bafang 250w vs a 1000w hub motor and the Bafang outperformed the larger, more powerful hub motor. The large direct drive hub motor was only rated at 35Nm of torque compared to the Bafang’s 80Nm.
If you are comfortable with your ability to install it, and you have an appropriate donor bike, then as long as you can live with some of the compromises, this is still one of the best electric bike kits available.
Where can I buy the Bafang BBS01B 250w?
The Bafang BBS01B 250w is available globally through e-commerce websites like eBay, Amazon and Aliexpress. The latter is usually cheaper, but returning a faulty item isn’t always so straightforward. My recommendation would be eBay or Amazon as the returns process is usually more straightforward, although the initial purchase price will be slightly higher.
Thanks for reading, if you have any questions please leave a comment below – I usually reply within 24hrs.