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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 a 5-year period, and I still think it’s one of the best road-legal options for converting your bike to electric assist.

Bafang BBS01B Specs

Motor PositionMid-Mounted (Bottom Bracket)
Motor Compatibility68-73mm BSA Threaded Bottom Bracket
Rated Motor Power250-watts to 350-watts
Motor Peak Power540-watts to 648-watts
Max Torque120Nm
Motor Rated Voltage36-volt
Controller Current 15-18-amps
IP RatingIP65
Motor Weight3.8 kg
Price $350 – $450
AvailabilityVarious online retailers


  • Road legal in the UK and EU (if speed limit is set)
  • Plus and play design
  • Very smooth and quiet
  • Can be programmed (with optional USB lead)
  • Efficient
  • 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 are currently the global leader in plug and play mid-drive electric bike conversion kits, and has been for a number of 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 to various bikes, ranging from low-step commuter bikes through to full-suspension mountain bikes.

bafang bbs01b 250w fitted to mountain bike
Bafang BBS01B installed on a Carrera MTB

The main criteria for installation is the size of the bike’s bottom bracket. It needs to be a standard 68mm-73mm 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 bike’s 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
  • Chainring
  • 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
bafang bbs01b 36v 250w electric bike kit

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 definitely 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 in 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 works 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.

bafang bbs01 250w review
A Bafang BBS01B 250w installed on a hybrid bike with Shimano Nexus 8 geared hub

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 a number of things to consider.

  • Controller failure is rare on this model nowadays, especially since Bafang upgraded the MOSFET’s 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 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 step 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 really 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 offer a 44t, 46t and 48t option. 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 Verdict

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 end result will be a bike that looks more like a factory produced e-bike.

bafang bbs01 250w fitted to a ladies mountain bike
Bafang BBS01B 250w installed on an Orbea MTB

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 out performed 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 personal recommendation would be eBay or Amazon as the returns process is usually more straightforward, although the initial purchase price will be slightly higher.

Compare Latest Prices on ebikepricecomparison.com
Links to the Bafang BBS02B 750w

Thanks for reading, if you have any questions please leave a comment below – I usually reply within 24hrs.


Passionate E-Bike advocate and enthusiast since 2016. Riding an electric bike helped me to lose weight, get fit and reignite my passion for cycling!

Tony has 238 posts and counting. See all posts by Tony

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