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How to convert a bike to electric power | Electric bike conversions explained

From powered wheels to friction drives and folding ebikes, we explain all

With all the noise currently being made about electric bikes, you might be tempted to get some extra push on your rides. But if you’re thinking ‘that’s all very well, but I want to keep my existing bike’, there’s good news – ol’ faithful can be rigged up with an ebike conversion kit.

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There are a number of ways to electrify your existing bike for assistance up those hills: you can fit a powered wheel, either front or rear; you can attach a drive unit to the bottom bracket; you can fit a motor above the rear wheel and drive it via friction; or, most sneakily, you can conceal a motor in the seatpost. (If you choose the latter, best you don’t go racing it.)

None of these options are particularly cheap, or easy, but they’re viable with most bikes, whether you ride a hybrid, mountain bike, road bike or even a folder, tourer or road bike.

Many can even be fitted by a competent home mechanic, if you’re feeling handy and have an afternoon spare.

There’s a steady stream of conversion kits launched on the likes of Kickstarter, so if you’re okay with taking a punt and waiting for a launch you might find a viable option at a discount price for early funders. Plus, there are some old favourites still being sold online.

So, what are your options? Let’s take a look at the best ways to convert your normal bike into an electric bike.

Powered ebike wheels

Swytch universal ebike kit
The Swytch is a good example of a readily available universal electric bike conversion kit that uses a motor at the front hub.
Swytch

This is probably the most practical option for many people: swap out one of your normal, non-powered wheels for one with a special hub that contains a motor, adding a battery and the gearing needed to turn it.

Sounds simple, but the main downside is that it adds rotating mass to your bike, which feels harder to accelerate than non-rotating mass.

There’s a steady stream of front and rear wheel conversion kits on Amazon and eBay, all looking suspiciously similar, priced from around £150 and with names you’ve never heard of. An oversized hub drives the bike and there’s a strap-on battery pack. 

Be careful of systems controlled by a throttle (also called “twist-and-go”) though. Legally, they’re classified as electric motorcycles rather than ebikes and need to be taxed and insured. Take a look at our ebike FAQs for more information.

A more polished option is the Copenhagen Wheel, which uses technology developed by MIT (Massachusetts Institute of Technology) and comes with either a 250-watt or 350-watt motor. Replacing a rim brake rear wheel, it has a range of around 30 miles / 48km and weighs 7.6kg. 

It’s controlled via a smartphone app and works with singlespeed or 7- to 10-speed Shimano drivetrains. It’s currently available in the USA only at a price of $1,749 from superpedestrian.com.

Swytch is a UK brand offering a front wheel conversion kit for 26in and 28in bikes. Weighing 3.5kg for the standard version with a 35km range or 5kg for the 50km range Tour. Swytch also offers a conversion kit for Brompton bikes. Prices are TBC.

Another UK-based provider, Cytronex’s kit has a 2kg front hub motor with the battery mounted using bottle cage bolts on the down tube, for a total weight of 3.6kg. It includes a patented single sensor that monitors the rear sprocket, pedalling speed and bike speed, replacing the three separate sensors usually needed to make the ebike legal. Claimed range is 25 miles and price is £995. 

E-Bikes Direct offers a few front wheel conversion kits priced from £350, although the cheapest kit currently available is the Conv-e, priced at £750.

There’s a choice of wheel sizes from 20in up to 700c and a 10Ah battery with a claimed range of 20 to 40 miles. It’s another throttle-operated “twist-and-go” system though.

Then there’s the FlyKly Smart Wheel, which is also operated via a smartphone app. It comes in three sizes: 28in for city bikes, 26in for mountain bikes and 20in for folding bikes. 

It claims a range of 25 to 60 miles / 40 to 100km, and will assist you up to 16mph / 25kph with its 250-watt motor.

Impressively, it’s said to be around half the weight of the Copenhagen Wheel, at 3kg. It costs from €1,199 from flykly.com.

Rear-mounted friction drive ebike conversion kit

The Rubbee is compatible with wheels ranging from 16 to 29in
Friction drive electric bikes are far from a new idea.
Oliver Woodman/Immediate Media

Readers of a certain age may remember earlier incarnations of these in the 1980s/90s: a box that sits on your rear wheel and powers it via friction with a rubber flywheel driven by a motor.

Sadly, we never got to fit one to our Raleigh Choppers and Muddy Fox mountain bikes, so didn’t find out if they were any good. 

The idea hasn’t gone away, though, and lives on in devices such as the Rubbee, which promises bolt-on electric assistance for nearly any bike. 

Rubbee’s base model has a claimed weight of just 2.8kg, with a 16km range that can be extended up to 48km with the top-spec, 4kg version.

It works with any wheel diameter between 16in and 29in, has an integrated carrying handle and clips on and off your seatpost. Pre-order prices start from €499.

One more slant on this idea comes from the 3.2kg go-e ONwheel, which hangs beneath the bike and presses a powered roller against the rear wheel. Power level can be selected either via a handlebar mounted control unit or a smartphone app. 

The default setting provides up to 250 watts of assistance and a maximum speed of 25kph, with a range of up to 60km.

Where legal, performance can be increased to 600 watts of assistance and up to 45kph via the app – the makers say: “It is your responsibility to set the maximal limits in the app according to local speed and power limits”. The go-e ONwheel costs from €749 from go-e.bike.

Concealed ebike conversion kit

Vivax Assist ebike drive system
The Vivax Assist hides a motor in the seat tube of the frame and applies power directly to the axle of the crank.
Vivax

Now we come to the low-key way to do it – hiding a motor inside your bike so no one knows it’s there. 

The Vivax Assist is the best-known device for doing this: a kit can be bought for around €2,999 including installation and includes a small 200-watt motor that sits inside a bike’s seat tube and drives the crankshaft via a bevel gear and a battery that goes in a bottle cage. 

It provides assistance for at least 60 minutes of riding, according to Vivax, and there’s a handlebar-mounted switch for activating the motor. The makers say the whole kit weighs just 1.8kg, but it must be fitted by a specialist.

It’s the system that was used by Belgian cyclocross pro Femke Van den Driessche in 2016 to power her way to victory in her home championships. She was found out at a subsequent race, got a six-year ban and quit racing.

Mid-drive ebike conversion kit

TongSheng Mid drive motor system
eBay and Amazon are inundated with mid-drive motor conversions like this one from TongSheng.
TongSheng

Many commercially available ebikes are powered with motors mounted around the bottom bracket, near the pedals.

These have the advantage of placing the weight low down on the bike – making it more stable – but be warned, they can get damaged hitting rocks, kerbs and other obstacles, being so low-slung.

This isn’t just a ready-made option though, you can also buy aftermarket conversion kits with mid-drive units. 

Bafang is a brand that is increasingly focusing on complete ebikes, but it also offers a mid-drive conversion kit on Amazon, as well as wheel hub motors. 

Priced from £360, Bafang says that the conversion is easy to install using “only a few tools” to remove the bottom bracket and fit the drive on the front of the down tube.

As above, be careful of throttle-controlled kits that won’t pass the UK ebike regulations and will legally be considered a moped. 

You’ll find other mid-motor systems on Amazon too, such as that from TongSheng, which is claimed to fit 95 per cent of standard bike frames and be 30 per cent lighter than a Bafang unit.

It uses a torque sensor, so should fall within the ebike regs, and is priced from around £300 – although that doesn’t include a battery.

And German brand Pendix has a mid-drive system priced from €999 to €2,190 that weighs from 5.4kg for a 28km range. It replaces a BSA bottom bracket and can be fitted to folding bikes as well as a wide range of normal machines.

Folding ebike conversion kit

Electric Concepts Brompton conversion kit
The Brompton electric conversion from Electric Concepts is one of many kits available to electrify an existing Brompton.
Electric Concepts

So what else can you do if you’ve got a folding bike and want to join the electric revolution? 

Well there’s good news if you’ve got a Brompton – a number of ebike conversion kits are available. They generally work with a powered hub in the front wheel and a battery carried in a bag mounted on the front.

Swytch has a Brompton kit priced at £999, although discounts of up to 50 per cent are sometimes available on the site.

As with its other systems, there’s a front wheel hub motor, a clip-on power pack and a bottom bracket torque sensor. Quoted range is up to 50km.

Swytch will also build wheels for folders with other wheel sizes and different fork blade widths, such as Dahon’s models.

UK firm Nano Electric Bikes offers kits costing from £835, running on a lightweight 2kg motor. You’ve got the option of using a twist-grip throttle or thumb throttle, although with a pedal sensor, the company says that its kits comply with UK and EU regs. 

Range is claimed to be up to 40 miles / 64km with a top assisted-speed of 25mph / 40kph. It also offers a fitting service at several sites in England.

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There’s also a rear wheel Brompton kit available from Israeli firm Electric Concepts. The rear triangle is swapped out for a titanium or steel unit, with an internal battery and a quoted weight around 14kg. Range is said to be from 30km up to 90km. Converted into GBP, the price is around £1,350.