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Comparison

Conversion kit vs buying a new e-bike

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In short

A conversion kit is worth it if you already own a sound bike that fits you well, has good brakes and a suitable frame, and you are happy to fit and set up the kit or pay a shop to. A new e-bike is the better choice if your bike is old or worn, has weak brakes or a carbon fork, or if you want a single warranty, integrated design and easy resale. Both can be legal 250 W EAPCs in the UK.

Products for this job

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Our verdict

Convert if you own a sound steel or aluminium bike with good brakes that fits you well and you are happy to fit and set up a 250 W kit. Buy a new e-bike if your bike is worn or unsuitable, or if you value integrated design, one warranty and easier resale.

Converting a bike you already love sounds like the best of both worlds: your familiar ride with a motor added. Often it is. But kits add weight in places the bike was not designed for, and the finished result depends on the bike underneath. This guide compares converting with buying new on the points that matter: weight, brakes, frame suitability, fitting, warranty and resale.

Side-by-side comparison

These are general differences. A well-chosen kit on a good bike can match a budget e-bike, while a kit on a tired bike rarely does.

  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.
FactorConversion kitNew e-bike
Fit and familiarityKeeps your current bike and fitNew bike, choose the right size
DesignParts added to a non-electric frameFrame designed around motor and battery
WeightKit adds several kg, often at one endWeight placed by design
BrakesYour existing brakesChosen for e-bike weight and speed
FittingDIY or bike shopReady to ride or minor assembly
WarrantyKit only; bike parts separateOne warranty covering the whole bike
ResaleHarder to value and sellEasier to sell
Legal statusEAPC if set up to 250 W and 15.5 mphEAPC if sold as one and unmodified
Conversion kit vs new e-bike

Is your bike a good candidate?

The bike underneath decides how well a conversion turns out. Good candidates are steel or aluminium hybrids, touring bikes and hardtail mountain bikes that fit you well and are in good condition. Disc brakes or strong, well-adjusted rim brakes are important because the bike will be heavier and you will ride faster on average.

Poor candidates include carbon frames or forks, bikes with worn wheels or cracked frames, very light road bikes and bikes with unusual axle or bottom bracket standards. Our can you make a normal bike electric guide covers frame and fork checks in detail.

  • Frame and fork: steel or aluminium, no cracks or dents.
  • Brakes: disc, or good rim brakes with fresh pads.
  • Wheels: true and sound, with sizes the kit supports.
  • Fit: the bike is comfortable for longer rides.
  • Dropouts and bottom bracket: compatible with the kit's stated sizes.

Weight and handling

Kits add the weight of a motor, battery, controller and wiring. A front hub kit puts motor weight on the front wheel, and a handlebar or rack battery shifts the balance further. That can make steering feel heavier. A mid-drive keeps weight low and central but needs more work to fit. Our hub motor vs mid-drive guide explains the trade-offs.

Factory e-bikes place the battery low on the down tube or in the frame, and pick frame stiffness and brakes for the extra weight, so they usually handle more predictably.

Fitting and set-up

Fitting a hub kit is within reach of a confident home mechanic: swap the wheel, fit the battery mount, pedal sensor, brake levers and display, then tidy the cables. A mid-drive kit means removing the cranks and bottom bracket. Either way, the controller must be set to cut assistance at 15.5 mph and any throttle limited to 6 km/h, as covered in are conversion kits legal in the UK. Our conversion kit fitting guide walks through the steps.

If you are unsure about brakes or wiring, ask a bike shop to fit or check the kit.

Note:Use the charger supplied with the kit's battery and charge where you can keep an eye on it. Make sure brakes are in good condition before riding a converted bike, and have a qualified mechanic check the work if you are unsure.

Warranty, spares and resale

A new e-bike comes with one warranty for frame, motor and battery, and a shop or brand to go back to. With a kit, the kit maker covers the electrical parts, while your bike's frame and components are on their own. If something fails, working out which part is at fault can take longer.

Converted bikes are also harder to sell, because buyers cannot easily judge the fitting quality or legal set-up. A recognised factory e-bike is simpler to value. If resale matters, buying new usually wins.

Which suits you

Convert if you have a good bike you love, want to keep it, and are happy with some fitting work. Buy new if your current bike is tired or unsuitable, you want integrated design and a single warranty, or you plan to sell later. Our electric bikes under 1,000 guide and electric hybrid bikes guide show ready-built 250 W options.

See ready-built e-bikes under 1,000 →

Frequently asked questions

Are e-bike conversion kits any good? A good 250 W kit on a sound, suitable bike can work very well. On a worn or unsuitable bike, results are poorer.

Is a converted bike road legal in the UK? Yes, if it meets the EAPC rules: 250 W rated motor, assist to 15.5 mph, pedal assist and a plate.

Do I need new brakes for a conversion? Not always, but they must be in very good condition. Many people upgrade pads or move to disc brakes.

Can a bike shop fit a kit? Many will. Ask in advance, as some shops only fit kits they sell.

What you need

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