Converting a suitable bicycle to electric power typically costs about £500 to £1,500 in the UK, depending on the motor, battery capacity, component quality and whether you fit the kit yourself. Premium Bafang mid-drive builds and long-range batteries can cost more, while a basic hub-motor conversion may cost less.
This guide breaks down the real costs and shows how to convert a bike to an e-bike without buying incompatible parts.
Typical e-bike conversion costs
- Hub-motor kit: approximately £250–£700 before the battery.
- Bafang mid-drive kit: approximately £450–£900 before the battery.
- Quality battery: approximately £250–£700 depending on voltage, capacity and cell brand.
- Display, sensors and accessories: often included, or £50–£200 separately.
- Professional fitting: commonly £150–£400 depending on complexity.
- Brake and drivetrain upgrades: allow £100–£400 when needed.
The cheapest kit is not always the cheapest finished build. A reliable battery, compatible controller and correctly installed torque arms can prevent expensive failures.
Step 1: Check whether your bike is suitable
Start with a structurally sound frame, wheels in good condition and effective brakes. Check available space for the battery and controller. Measure the wheel diameter, dropout width and bottom-bracket dimensions before ordering.
Carbon frames, unusual bottom brackets and lightweight forks may need specialist advice. Powerful hub motors place extra force on the dropouts, while mid-drive motors increase load on the chain and cassette.
Step 2: Choose a hub motor or mid-drive motor
A front or rear hub motor is usually simpler and more affordable. It suits flatter commutes and riders who want a straightforward conversion. A Bafang mid-drive motor uses the bicycle's gears, which can improve climbing and efficiency on varied terrain.
Mid-drives normally feel more natural and keep wheel removal straightforward, but fitting is more involved and drivetrain wear can be higher. Read our Bafang BBSHD guide for a deeper comparison.
Step 3: Match the battery to the system
Voltage must match the controller and motor system. Amp-hours indicate capacity, while watt-hours provide a better basis for comparing likely range. For example, a 48V 15Ah battery stores about 720Wh.
Choose a battery with a suitable battery-management system, reputable cells and a mounting position that does not compromise handling. Never use an incompatible charger, and do not charge a damaged or swollen battery.
Step 4: Install the kit safely
- Fit the motor according to the manufacturer's torque settings.
- Install torque arms where required for a hub motor.
- Mount the battery securely and protect cables from sharp edges.
- Fit the display, brake cut-offs and pedal-assist sensor.
- Connect colour-coded plugs without forcing them.
- Lift the driven wheel and test at low power before riding.
- Recheck fasteners and cable routing after the first short ride.
For the complete sequence, see our step-by-step e-bike conversion kit tutorial.
UK road-legality considerations
A conversion used as an ordinary cycle on public roads must meet EAPC rules: usable pedals, no more than 250W maximum continuous rated motor power and assistance that cuts off at 15.5mph. A higher-powered build may be intended for private land or may require motorcycle-type approval, registration, insurance and licensing.
Is conversion cheaper than buying an e-bike?
Conversion offers excellent value when you already own a comfortable, suitable bicycle. A complete factory e-bike may be better if your current bike needs new brakes, wheels and drivetrain parts, or if you want an integrated warranty and cleaner cable routing.
Compare e-bike conversion parts and complete electric bikes at E Bike Market.