Original price was: £443.30.£399.20Current price is: £399.20.
Bafang BBS01B 250W mid drive conversion kit, available in UART and CAN-BUS versions. Road-legal in the UK, 80Nm max torque, 36V system. For frames with a bottom bracket wider than 73mm, please contact us.
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12 months warranty from date of purchase.
The Bafang BBS01B 250W mid drive kit is available in both UART and CAN-BUS versions — choose your version under “Model” when you order. 80Nm max torque · 36V system · 68–73mm bottom bracket · Geared mid-drive with freewheel · DZ41 or 850C display options · 12-month warranty
The single most important advantage of this motor over any hub motor system is where it sits. Mounted at the bottom bracket — the lowest, most central point of the bicycle frame — the mid drive configuration keeps the centre of gravity low and centred between both wheels. The result is handling that feels natural and balanced rather than rear-heavy or sluggish: sharper cornering, more stable weight distribution under acceleration, a bike that steers like a bicycle rather than a motorised vehicle dragging a heavy rear wheel.
This geometry advantage is compounded because this kit drives through the bicycle’s existing drivetrain. The motor spins the crank, the crank drives the chain, the chain runs through your existing cassette and derailleur — so the motor benefits from every gear ratio on your bike, low gears for steep climbs and high gears for fast flat riding. A hub motor has one effective gear ratio. This motor has as many as your bike does.
We sell the Bafang BBS01B 250W mid drive kit in two versions: 250W UART and 250W CAN-BUS. Both use the same 250W motor, the same 80Nm of torque and the same 68–73mm bottom bracket fitment, and both are road-legal in the UK. The only difference is the communication protocol — how the motor controller talks to the display and the rest of the system. Pick your version from the “Model” option when you order.
UART is Bafang’s original communication standard. It works with the widest range of displays, programming cables and configuration software. With a USB programming cable and the Bafang configuration tool you can adjust assist levels, PAS sensitivity and wheel size settings yourself. Choose UART if you like to set up your own motor, or if you want to use displays and accessories you already own.
CAN-BUS is Bafang’s newer protocol. The controller, display and battery exchange data in both directions in real time, which gives more accurate live information and better error reporting and diagnostics. CAN-BUS systems are set up through Bafang’s own software rather than the open configuration tool used on UART motors. Choose CAN-BUS if you want a more integrated system with clearer fault reporting, or if you’re matching other CAN-BUS components.
The display, controller and wiring must all use the same protocol. A UART display won’t work on a CAN-BUS motor, and the reverse is also true. If you buy spares later, check which version your kit is first.
The headline specification that separates this 250W mid drive kit from everything in the hub motor category is torque. At 80Nm maximum effective torque, this motor produces more rotational force at the crank than most 1000W direct-drive hub motors produce at the wheel — a 250W motor that climbs hills better, responds more immediately to pedal input, and maintains usable power at lower speeds where hub motors typically struggle.
The geared mid drive architecture multiplies motor torque through the reduction ratio — 1:21.9 in the BBS01B — before it even reaches the chainring, producing wheel torque figures the raw wattage rating doesn’t suggest.
This BBS01B is designed for bottom brackets with a shell width of 68–73mm and an internal diameter of 33.5mm — covering the JIS/BSA threaded standard used on the vast majority of road bikes, mountain bikes, hybrid frames and city bikes. The 33.5mm axle diameter is specific to the BAFANG BBS mid drive family and isn’t compatible with press-fit or proprietary bottom bracket standards without adaptation.
This kit is available with two display options depending on your build requirements. The DZ41 is a clean, functional LCD unit delivering speed, battery level, assist mode and trip data in a compact, handlebar-mounted format. The 850C is a full-colour backlit display with a larger screen, richer data presentation and a more premium interface — the preferred choice for builds where rider information and display quality are a priority. On the UART version, both displays connect directly to the BBS01B controller with no adapter required. Whichever version you choose, the display must use the same protocol as the motor — UART or CAN-BUS.
This motor is a 36V system, and matching battery packs are available in three capacities when ordering: 36V 15Ah, 36V 20Ah and 36V 35Ah — all in downtube format for a clean, integrated appearance. Higher capacity means longer range per charge with no change to the motor’s performance output.
For the full range of 36V compatible packs and other battery options, visit the Batteries category page.
Prefer a pack in a custom capacity? Use our Custom Battery Builder to build a 36V battery to your exact spec and get an instant price.
Unlike direct drive hub motors, this motor uses an internal gearbox — a reduction gear set that steps the motor’s high-RPM output down to a useful crank speed. This gearing does two things: it lets the motor operate within its most efficient RPM range regardless of riding speed, keeping thermal load low and energy consumption efficient, and it enables the motor to freewheel when not under power — an internal clutch disengages the motor from the drivetrain during unpowered riding, eliminating the drag that makes direct drive hub motors exhausting to pedal without assistance.
At 3.8kg, this motor adds minimal weight to the bicycle, positioned optimally at the bottom bracket.
The BBS01B uses a cadence-based pedal assist sensor that detects pedalling motion and applies motor assistance proportionally. As you pedal, the motor assists; stop pedalling and it cuts out. The result feels intuitive and natural — particularly effective for commuting and touring, where consistent, low-effort cruising is the priority. E-brake support is integrated, cutting motor output instantly when either brake lever is applied.
The BBS01B 250W is the entry point to the BAFANG mid drive family — the most compact, lightest and most efficient unit in the range. For builders who need more power for heavier loads, steeper terrain or faster riding, the BAFANG mid drive 750W UART delivers triple the rated output on the same mid drive platform, and the BAFANG mid drive 750W CAN-BUS offers the same power on the CAN-BUS protocol. For maximum performance at the top of the range, the BAFANG BBSHD 1000W is the benchmark high-power mid drive unit, also available in UART and CAN-BUS. Note that the 750W and 1000W kits are for off-road and private-land use only.
For the complete overview of all conversion options available, visit the Conversion Kit category page.
Every BAFANG Mid Drive 250W kit purchased from All4eBikes, UART or CAN-BUS, is covered by a 12-month warranty against manufacturing defects in the motor and all included components, alongside a 30-day return window for complete purchase confidence.
Yes. We sell the Bafang BBS01B 250W mid drive kit in a CAN-BUS version and a UART version. Choose the one you want under “Model” when you order.
Yes. The UART version of the 250W kit is available on this page. It’s the version to choose if you want to set up the motor yourself with the Bafang configuration tool.
Yes. Both versions are the same 250W motor, so both stay within the UK’s 250W / 15.5mph EAPC limit. The protocol changes how the components communicate, not the motor’s power.
No. UART and CAN-BUS components are not cross-compatible. The display and controller must use the same protocol as the motor version you buy.
We’ll help you choose UART or CAN-BUS and confirm BB width, display choice and battery options before you order. Get in touch on WhatsApp.
📍 2 Beresford Road Lane, Roath, Cardiff CF24 1QU | 📞 07920 781 258
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