UK-legal e-bike conversion: pick a kit that won't get you nicked (or set your house on fire)

Most kits sold online are too powerful for UK roads. Check yours, then find the right type for your bike, hills and budget.
Some links are affiliate links. Facts checked 24 Oct 2026. Not legal advice: check GOV.UK before you ride.
1. Is this kit road-legal?
2. Which kit suits you?
Your pick
Front hub kit
Cheapest and easiest to fit: swap the front wheel, add battery and sensor. Good for flat and rolling roads. Needs a steel or strong alloy fork with torque arms; never a carbon fork.
250W front hub e-bike conversion kits →ADE-bike torque arms →ADYose Power kits (check it's the 250W one) →ADRear hub kit
Better grip and feels more natural than a front kit. Harder to fit because of the gears on the back wheel. Works with carbon or suspension forks.
250W rear hub e-bike conversion kits →ADMid-drive kit
Best on steep hills because the motor drives through your gears. Hardest fit and dearer. Buy the 250W version only (e.g. Bafang BBS01B 250W); the BBS02 and other 500-1000W versions are not road-legal.
Bafang BBS01B 250W mid-drive kits →ADGet it fitted
No tools? A bike shop can fit a kit for you. Fitted kits such as Boost cost about £690. Ask the shop to confirm it's 250W, 15.5mph cut-off, no throttle.
Read about Boost fitted kits →250W front hub e-bike conversion kits →AD3. Battery safety: the bit that matters most
Battery fires from e-bikes and e-scooters have killed at least 18 people in the UK since 2019. Coroners traced fatal cases to cheap replacement batteries bought online and fitted to converted bikes.
- Buy the battery and charger together from the kit maker. Never mix chargers.
- Avoid no-name replacement batteries from marketplaces.
- Charge while you're awake and home, not overnight, and never by your front door or on the stairs.
- Fit a working smoke alarm where you charge.
- Stop using a battery that's swollen, hot, smells or has been dropped hard.
The UK rules in one go
- Motor: 250W continuous rated power max.
- Assist cuts out at 15.5mph.
- No throttle that drives the bike without pedalling, unless the bike is approved.
- Rider 14+.
- Break any of these and it's a moped: register, tax, licence, insurance, motorbike helmet. Police can seize it.
- The 500W and throttle plans were dropped in January 2025. Nothing has changed in 2026.
4. Rather buy one ready-made?
A whole e-bike costs more than a kit (roughly £700 to £2,500) but there's no fitting and it comes legal out of the box. Look for 250W, 15.5mph and an EN 15194 sticker.
250W UK-legal commuter e-bikes →ADEMOKO C99: 250W, 25km/h UK-legal fat-tyre commuter →AD250W folding e-bikes →ADSold Secure Gold bike locks →AD