From power wheels to friction drive and folding electric bicycles, we explain everything

Authors: Paul Norman, Jamie Beach

Given all the current noise related to electric bicycles, you might want to get some extra boost during riding. However, if you think "this is all good, but I want to keep my existing bike", then the good news is-ol'loyal can use an electric bike modification kit for assembly.

There are many ways to power up your existing bicycle to assist uphill: you can install the front wheel or the rear wheel; you can connect the drive unit to the bottom bracket; you can install a motor above the rear wheel and drive it by friction ; Or, most sneakily, you can hide a motor in the seatpost. (If you choose the latter, it is best not to participate in the competition.)

None of these options are particularly cheap or easy, but they are suitable for most bicycles, whether you are riding a hybrid, mountain bike, road bike, or foldable bike, station wagon, or road bike.

Many can even be installed by a competent home mechanic, if you feel convenient and have an afternoon free time.

A steady stream of conversion kits are launched on platforms like Kickstarter, so if you are willing to take the risk and wait for the release, you may find viable options for early funders at a discounted price. In addition, there are some old favorites that are still on sale online.

So, what are your options? Let's take a look at the best way to convert an ordinary bicycle to an electric bicycle.

For many people, this may be the most practical option: replace an ordinary, unpowered wheel with a wheel with a special hub that contains an electric motor, add a battery and the gears needed to turn it.

It sounds simple, but the main disadvantage is that it adds a spinning mass to your bike, which feels harder to accelerate than a non-spinning mass.

There are a steady stream of front and rear wheel conversion kits on Amazon and eBay. They all look very similar, with a price of around £150, and names you have never heard of. A bicycle is driven by an oversized wheel hub, and there is also a belt-type battery pack. 

But be careful with systems controlled by the throttle (also called "twist-and-go"). Legally speaking, they are classified as electric motorcycles rather than electric bicycles and require taxation and insurance. Please check our e-bike FAQ for more information.

A more refined option is the Copenhagen wheel, which uses technology developed by the Massachusetts Institute of Technology (MIT) and is equipped with a 250-watt or 350-watt motor. After replacing the rear wheel with the rim brake, it has a cruising range of approximately 30 miles/48 kilometers and a weight of 7.6 kg. 

It is controlled via a smartphone app and can be used with single-speed or 7 to 10-speed Shimano transmission systems. It is currently only sold in the United States from superpedestrian.com for $1,749.

Swytch is a British brand that provides front wheel modification kits for 26-inch and 28-inch bicycles. The standard version for the 35 km range weighs 3.5 kg, and the weight for the 50 km range tour is 5 kg. Swytch also offers retrofit kits for Brompton bicycles. The price is to be determined.

The kit from Cytronex, another British supplier, has a 2 kg front wheel hub motor. The battery is installed with a bottle cage bolt on the lower tube, and the total weight is 3.6 kg. It includes a patented single sensor that monitors the rear sprocket, pedal speed and bicycle speed, replacing the three separate sensors normally required to legalize electric bicycles. The claimed range is 25 miles and the price is £995. 

E-Bikes Direct offers some front-wheel modification kits priced at £350, although the cheapest kit currently is Conv-e, priced at £750.

You can choose a wheel size from 20 inches to 700c and a 10Ah battery with a claimed cruising range of 20 to 40 miles. However, it is another throttle-operated "rotary" system.

Then there is the FlyKly smart wheel, which can also be operated through a smartphone app. It comes in three sizes: 28 inches for city bikes, 26 inches for mountain bikes, and 20 inches for folding bikes. 

It claims a cruising range of 25 to 60 miles/40 to 100 kilometers and helps you reach 16 miles/hour/25 kilometers/hour through its 250-watt electric motor.

What is impressive is that it is said to weigh about half of the Copenhagen wheel, 3 kg. The price of flykly.com is 1,199 Euros.

Readers of a certain age may remember an early version from the 1980s/90s: a box mounted on the rear wheel and powered by friction with a rubber flywheel driven by an electric motor.

Unfortunately, we have never installed one for our Raleigh Choppers and Muddy Fox mountain bikes, so we didn't find out if they were any good. 

However, this idea has not disappeared, and it exists in devices such as Rubbee, which promises to provide bolted electric assist for almost all bicycles. 

Rubbee's basic model claims a weight of only 2.8 kilograms, a cruising range of 16 kilometers, and the highest specification 4 kilogram version can be extended to 48 kilometers.

It is suitable for any wheel diameter between 16 inches and 29 inches and has an integrated handle and clamps on and under the seatpost. Pre-order prices start from 499 Euros.

Another tendency of this idea comes from the 3.2 kg go-e ONwheel, which hangs under the bicycle and presses a power roller onto the rear wheel. The power level can be selected through the control unit installed on the handlebar or the smartphone app. 

The default setting provides up to 250 watts of assistance, a top speed of 25 kilometers per hour, and a cruising range of up to 60 kilometers.

In legal cases, performance can be increased through the app to 600 watts of auxiliary and up to 45kph-the manufacturer says: "It is your responsibility to set the maximum limit in the app according to local speed and power limits." go-e ONwheel is priced at 749 Euros from go-e.bike.

Now we use a low-key way to do this-hide a motor in your bike so that no one knows where it is. 

Vivax Assist is the most well-known device: the kit including installation costs about 2,999 Euros and includes a small 200-watt motor located in the bicycle seat tube and driven by a bevel gear and a battery to drive the crankshaft in the bottle cage. 

According to Vivax, it can provide assistance for at least 60 minutes of riding, and has a switch mounted on the handlebar to start the motor. According to the manufacturer, the entire kit weighs only 1.8 kg, but it must be installed by an expert.

Femke Van den Driessche, a Belgian cross-country professional athlete, used this system in 2016 to power her to win the home championship. She was found in a subsequent game, suspended for six years and withdrew from the game.

Many commercially available electric bicycles are powered by motors mounted around the bottom bracket, close to the pedals.

These have the advantage of putting weight on the bike-making it more stable-but be aware that they can be damaged by hitting rocks, curbs and other obstacles, so the suspension is too low.

However, this is not just a ready-made option, you can also purchase an after-sales conversion kit with a mid-drive unit. 

Bafang is a brand that is increasingly focusing on complete electric bicycles, but it also offers mid-drive conversion kits and in-wheel motors on Amazon. 

Starting at £360, Bafang says that this conversion is easy to install, "with a few tools" you can remove the bottom bracket and install the drive on the front of the down tube.

As mentioned above, please note that it will not pass the UK electric bicycle regulations and will be legally regarded as a throttle control kit for mopeds. 

You can also find other mid-motor systems on Amazon, such as the system from Tongsheng, which is said to fit 95% of the standard bicycle frame and is 30% lighter than the Bafang device.

It uses a torque sensor, so it should belong to ebike regs, and the price is about £300-although the battery is not included.

The price of the mid-drive system of the German brand Pendix ranges from 999 Euros to 2,190 Euros, and the weight within 28 kilometers is 5.4 kg. It replaces the BSA bottom bracket and can be installed on folding bicycles and various ordinary machines.

So, if you have a folding bike and want to join the electric revolution, what else can you do? 

If you have Brompton, the good news is-there are many electric bike conversion kits available. They usually work with the power hub in the front wheel and the battery carried in the front bag.

Swytch has a Brompton kit that sells for £999, but sometimes the website offers discounts of up to 50%.

Like other systems, there is a front wheel hub motor, a clip-on power pack and a bottom bracket torque sensor. The quotation range can be up to 50 kilometers.

Swytch will also make wheels for folders with other wheel sizes and different fork blade widths, such as Dahon's model.

The British company Nano Electric Bikes offers a kit priced at £835, which runs on a lightweight 2kg motor. You can choose to use the twist handle throttle or the thumb throttle, and despite the pedal sensor, the company says its kit complies with UK and EU regulations. 

It is said that the cruising range can reach 40 miles/64 kilometers, and the maximum assist speed is 25 miles/hour/40 kilometers/hour. It also provides fitting services at various locations in England.

The Israeli company Electric Concepts also provides rear-wheel Brompton kits. The rear triangle is replaced by a titanium or steel unit with a built-in battery and weighs approximately 14 kg. It is said that the range is from 30 kilometers to 90 kilometers. Converted into pounds, the price is approximately 1,350 pounds.

Paul has been cycling since he was a teenager and has been writing about bicycle technology for nearly a decade. Before it was invented, he liked gravel, riding a cross-country bike through the south hills, and along a muddy path through Chiltern. He also dabbled in cross-country mountain biking, and then returned to cycling.

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