Bafang BBS02B 350W-750W Mid-Drive E-Bike Conversion Kit (UART, 36-52V)

The Bafang BBS02B mid-drive conversion kit (UART) turns a regular bicycle into a smooth, hill-climbing e-bike. Because it drives through your bike's own gears, a BBS02B climbs better and uses less battery than a hub motor of the same wattage. Choose from four power versions, from a light 350W commuter setup to a 750W kit with 120 Nm of torque.

Approximate top speed: 20 to 28 mph (32 to 45 km/h) depending on version (see table below). Speeds are approximate on flat ground with a 26"-29" wheel and depend on battery, gearing, rider weight and terrain. You can also set a lower speed limit in the display.

Display required: choose your display when you order. The display is priced separately, which keeps the kit price lower and lets you pick the one you want. Need the kit without a display? Contact our sales team and we'll help you check out.

Golden Motor is an authorized Bafang reseller. Every kit is backed by our 1-year warranty and our own support team.

Choose Your Power Version

Not sure which wattage you need? Read our guide: What Wattage Motor Do I Need?

What's in the Box

• Bafang BBS02B mid-drive motor with built-in controller (your choice of version)
• 46T chainring
• Crank arms (pedals not included)
• Thumb throttle
• Speed sensor and magnet
• All cables, wiring, installation hardware and tools

Display, battery and charger are sold separately. Any 36V, 48V or 52V battery that matches your version works. Shop e-bike batteries.

Compatible UART Displays

Bafang 860C | Bafang DPC-18 | Bafang C965 | Bafang C961 | Bafang 600C | EggRider V2 | EggRider C1

Why UART?

UART is Bafang's original communication protocol and the most popular choice for DIY builds. It works with the widest range of displays, and you can fine-tune power, pedal assist levels and speed limit yourself with a UART programming cable. See how to program your Bafang controller.

Important: UART and CAN Bus parts are not interchangeable. Displays, throttles and sensors must match your motor's protocol. For Bafang's newer system, see the BBS02B CAN Bus kit.

Specifications

• Motor type: brushless geared mid-drive, controller built in
• Voltage: 36V, 48V or 52V depending on version
• Rated power: 350W, 500W or 750W
• Max torque: 80 to 120 Nm depending on version
• Max current: 18A to 25A depending on version
• Motor weight: 4.2 kg
• Efficiency: 80% or higher
• Waterproof rating: IP65
• Riding modes: pedal assist (cadence) and throttle
• Bottom bracket fit: 68-73mm. For 100mm or 120mm shells add the BBS02 extension kit. Press-fit frames need an adapter such as the Lekkie BB86/92 or Lekkie PF30.
• Install time: about 1-2 hours with basic tools

Recommended Add-Ons

• Lekkie OneNut or Bafang stabilizer bar to keep the motor tight on the bottom bracket
• 73mm bottom bracket screws or BB spacers for a snug fit
• Chainrings and cranks to fix chainline or change gearing
• Bafang parts and accessories

FAQ

Will a BBS02B fit my bike?
It fits most bikes with a standard 68-73mm threaded bottom bracket. Measure your bottom bracket width before ordering, and see our Bafang fitment guide.

Is it street legal?
The 750W version matches the 750W limit most US states use for e-bikes. See our e-bike law guide for your state's rules.

BBS02B or BBSHD?
The BBS02B is lighter and ideal up to 750W. For 1000W off-road builds, choose the BBSHD.

Installation Videos

Full step-by-step guide: Bafang Mid-Drive Installation.