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Are e-bike conversion kits legal in the UK?

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In short

Yes, a conversion kit is legal for road use in Great Britain if the finished bike meets the EAPC rules: a motor with a maximum continuous rated power of 250 W, assistance that cuts out at 15.5 mph (25 km/h), pedal-assist control with any throttle limited to 6 km/h, and a rider aged 14 or over. Kits rated at 500 W, 1000 W or more, or set up without speed limits, make the bike a motor vehicle in law.

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Converting a bike you already own is a popular way to go electric, and plenty of kits are sold in the UK. The kit itself is not legal or illegal in isolation. What matters is the bike you end up with. This guide explains which kits suit road use, how to set up the controller and throttle, what to put on the plate and what to avoid in online listings. It is general information, not legal advice, so check gov.uk for the rules in force.

The test is the finished bike

UK law looks at the bike as ridden. Once converted, it must meet the same electrically assisted pedal cycle (EAPC) rules as a factory-built e-bike. If it does, you can ride it on roads and cycle paths without a licence, registration, tax or insurance. If it does not, it is treated as a moped or motorcycle.

That means the label on the box matters less than the motor rating, the controller settings and how you use the throttle.

  1. 1Motor wheel or mid-drive unitFits: Front or rear dropouts, or the bottom bracket
  2. 2Battery with mountFits: Down tube bottle bosses or a rear rack
  3. 3ControllerFits: Battery mount or a frame bag
  4. 4Pedal-assist sensorFits: Behind the chainring, on the crank axle
  5. 5Brake levers with cut-offFits: Handlebar, in place of your levers
  6. 6DisplayFits: Handlebar, next to the stem
The parts of a typical conversion kit and where each one fits on the bike.
CheckWithin EAPC rulesOutside EAPC rules
Motor rating250 W continuous350 W, 500 W, 750 W, 1000 W or more
Assist cut-off15.5 mph (25 km/h)Higher limit or no limit
ControlPedal assist sensorThrottle only
ThrottleNone, or limited to 6 km/hFull-speed twist or thumb throttle
PlateMaker, power, voltage or speed shownNo markings
Conversion kit checks for road use in Great Britain

Choosing a kit that can be road legal

Look for kits sold specifically as 250 W for the UK or EU market. Many brands offer the same motor family at several power levels, and only the 250 W version suits road use. A front hub, rear hub or mid-drive can all be legal; the motor position does not change the law. Our hub motor vs mid-drive guide explains how they differ to ride and maintain.

Voltage on its own does not settle the question. Kits run at 36 V or 48 V and both can be legal at 250 W rated power, as explained in our 36 V vs 48 V guide. Be cautious of listings that quote only peak watts, or that describe the kit as off-road only. That phrase is usually a sign the kit is not intended for UK roads.

Setting up the controller and throttle

Most kits use a display with a settings menu. Before riding on the road, check the speed limit setting is 25 km/h, or 15.5 mph if the display uses miles. Some kits ship set to a higher figure for other markets, so do not assume.

If the kit includes a throttle, set it to a walk mode of 6 km/h or less where the controller allows it. If it does not, leave the throttle disconnected. Our throttle rules guide covers this in more detail. Brake levers with motor cut-off switches are not a stated legal requirement but are a sensible safety feature, and most kits include them.

  1. 1

    Check the motor label or paperwork shows 250 W continuous rated power.

  2. 2

    Set the display speed limit to 25 km/h (15.5 mph).

  3. 3

    Fit the pedal assist sensor so the motor only runs while you pedal.

  4. 4

    Limit or disconnect any throttle.

  5. 5

    Fit a plate or durable label with the details listed below.

  6. 6

    Keep the kit paperwork with your bike records.

What to put on the plate

An EAPC should carry a plate showing the manufacturer, the continuous rated power, and either the battery voltage or the maximum assisted speed. With a kit, the motor maker's details and the kit's rated power are the natural starting point. Some kits include a label; if yours does not, a durable engraved or riveted plate fixed to the frame is a common solution. Our EAPC plate markings guide shows where these details usually go.

Is your bike suitable for a kit?

Legal is not the same as safe. A motor adds weight and torque, so the frame, fork, wheels and brakes must be up to the job. Front hub kits need a sturdy steel or aluminium fork, ideally with torque arms where the maker recommends them, and are not suited to carbon forks. Rim brakes in poor condition, cracked frames and old wheels should be fixed before conversion.

If you are not confident about brakes, wheel fitting or wiring, ask a bike shop to fit or check the kit. Our conversion kit vs new e-bike guide helps you decide whether converting makes sense at all.

Note:Lithium batteries need care. Use the charger supplied with the kit, charge where you can keep an eye on it and stop using a battery that is damaged, swollen or unusually hot. Follow the maker's instructions.

Frequently asked questions

Are 1000 W conversion kits legal in the UK? Not for roads or cycle paths. A motor over 250 W rated power takes the bike outside the EAPC rules, so it is treated as a motor vehicle.

Can I fit a conversion kit to any bike? Many steel and aluminium bikes suit a kit, but carbon frames and forks, worn brakes and unusual wheel sizes may not. Check the kit maker's fitting guide.

Do I need to tell anyone I have converted my bike? There is no registration for an EAPC. Your insurer, if you have cycle or home cover, may want to know, so check your policy.

Where can I check the rules? The gov.uk page on electric bike rules sets out the official position. Our UK e-bike law check runs through the main tests.

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