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Cars & travel.

9 June 2021

Electric bikes: everything you need to know

Electric bikes have a battery and motor to help power you along. Discover the different types and what to be aware of before you buy
Matthew Knight
Ebike-lifestyle5

Electric bikes (e-bikes) have become increasingly popular. They can make a hilly or long commute more manageable, get you further afield on leisure rides, or restore a lapsed love of cycling. 

E-bikes have a few additional features over regular bikes that need to be considered before you buy, such as weight, motor position and battery range. 

In this guide we explain what you need to know to decide whether an e-bike is for you and how to choose the right one.

Our independent e-bike tests also reveal the e-bike systems that will go furthest before you need to recharge them - we've uncovered some that are completely unsuitable for hilly areas. See which motor and battery systems we recommend by heading to our top electric bike motor systems page.

Video: Electric bike buying guide

Watch our video to find out about the pros and cons of different types of e-bike, and decide if one of them might be for you.

How do electric bikes work?

The only difference between an electric bike and an ordinary bicycle is that it has a battery-powered motor to assist you with your riding. 

A small digital display allows you to switch between lower or higher amounts of motor input as you go. These are often called 'assistance levels'. 

So as you pedal you can choose an assistance level to make the motor match - or even double - your level of effort, helping to propel you along. 

How do e-bikes differ from other motorised vehicles?

You have to pedal for the motor to kick in, and electric bikes are restricted by law to go no faster than 15.5mph (25kph). These restrictions mean you don't need a licence or to tax/insure it - as you would with a scooter.

This doesn’t mean that you can’t go faster than 15.5mph on an e-bike, only that the e-bike's motor assistance will cut out at this speed.

If you want to go faster, then you will have to pedal harder  or be going downhill. 15.5mph is a good speed for cruising along on the flat, and will feel very quick when going uphill.

First Look: latest electric bikes - we've taken some newer models for a spin to bring you our first impressions

Do you still get exercise using an e-bike?

Yes. Any time you go out on a bike, e-bike or not, your heart rate will increase, you’ll breathe a little more deeply and you’ll be burning calories.

E-bikes have different assistance levels that vary the amount of support the motor provides. If you haven’t ridden a bike for years, then you can start off using a higher assistance level and build up stamina gradually.

Similarly, if you’re a very keen cyclist but you find yourself running out of puff on longer hills, then an electric bike could give you that extra boost while still giving you a workout.

How heavy are electric bikes?

An e-bike can often be up to 10kg heavier than a similar non-electric bike. A hybrid e-bike typically weighs between 22 and 25kg. A folding e-bike is typically lighter than this - as they are designed to be carried - coming in at around 16 to 18kg. 

The additional weight is due to the motor and battery. While this shouldn't affect you too much while riding, it's worth bearing in mind if you're likely to be transporting it - carrying an e-bike or lifting it into a car requires a bit of muscle.

There are models that weigh considerably less (the Hummingbird Electric weighs only 10kg), but these are usually built from carbon fibre and are much pricier. 

However, if you know you'll be regularly lifting your e-bike into a car, up stairs into a flat, or while hopping on and off public transport, then it may be best to invest in a lighter e-bike to make it more convenient to use. 

How much does an e-bike cost?

Prices for e-bikes vary from £500 to more than £5,000, however most cost between £1,500 and £3,000. Several factors can affect the price of an e-bike:

  • Motor position - e-bikes with a front and rear-hub motor tend to be cheaper than e-bikes with a mid-hub motor.
  • Range - bikes that get you further on a single charge need a battery with a larger capacity, and so cost more. However, we've found in our testing that higher-powered batteries don't always translate to more miles - it also depends on the motor they're paired with. See our e-bike motor reviews for our top picks.
  • Frame material - frames made of a lighter material, such as carbon fibre, cost more.

How to choose the best bike - our advice to help you choose the best bike to suit your lifestyle


E-bike motors explained: front vs mid vs rear-hub motors

Regardless of the type of electric bike you're looking to buy, a key thing to consider is the position of the motor on the bike. This can affect everything from how the bike handles to how easy it is to transport. 

As a general rule of thumb, mid-hub motors tend to be more expensive than front or rear-hub motors, but most people find they offer a smoother ride. 

Of course, the best way to determine which motor feels right for you is to test ride the e-bike for yourself, but the following pros and cons will help you narrow down your choice.

Front-hub motors

Positioned on the front wheel hub, they’re common on folding bikes and cheaper touring e-bikes (typically under £1,500).

Pros:

  • The motor doesn't wear down the chain - the motor is directly powering the wheel, rather than the drive chain 
  • You can customise gears easily.

Cons:

  • The bike can be unbalanced -  the front is heavier than the back 
  • Tricky to remove the front wheel for transportation 
  • Front wheel can slip on steep climbs if you don’t distribute your weight properly
  • The motor pulls you forward, rather than pushing you, which can feel strange.

Rear-hub motors

These are situated on the rear wheel hub. They also tend to cost less than £1,500.

Pros:

  • The motor pushes you forward, which feels more natural to most people than being pulled forward by a front-hub motor
  • The motor should wear down the chain less quickly than a mid-hub motor
  • Easy to customise the gears.

Cons: 

  • You need a specially designed rear wheel
  • Tricky to remove the rear wheel for transportation
  • The bike can be unbalanced - the back is heavier than the front. This issue is exacerbated if the battery is also located at the back and the bike doesn’t have front suspension.

Mid-hub motors

E-bikes with a mid-hub motor (sometimes called a mid-engine motor) are typically more expensive. They do have some significant advantages though.

Pros:

  • More balanced weight distribution, making it easier to lift and carry
  • Best for off-road riding because the centre of gravity is lower compared with front or rear-hub motors
  • You can easily customise, switch or replace wheels
  • Wheels are easy to remove for transportation.

Cons:

  • You can't customise the gear setup as easily. The crankset (pedals and front chain ring) can't be changed, although you can change the cassette (gears) on the rear hub so you're not completely limited
  • Drive chain can wear down more quickly.

Best rechargeable bike lights - find the brightest and lightest to keep you safe on the road

Which electric bike motor system is best?

Unquestionably the motor is the most important part of an e-bike. But with thousands of different e-bikes available to buy in the UK it can be hard to know where to start.

However, a significant number of e-bike manufacturers buy their motor systems from third-party suppliers. This means there are a lot of e-bikes on the market with the same motor, battery and display combinations.

Therefore finding a great electric bike motor system can really narrow down your search.

Brands such as Giant, Canon and Raleigh will fit out their e-bikes with motors from manufacturers such as Bosch, Shimano or Yamaha, then pair them with a lithium-ion battery and a digital control display.

Once you've chosen the motor system for you, you can then test-ride a handful of e-bikes to find the one that is the most comfortable, suitable and easy for you to ride.

We've tested nearly all of the third-party mid-hub e-bike motors available in the UK, and the difference in quality is stark.

  • Some e-bike motors don’t have enough juice to power you up a even a gentle slope.
  • The best e-bike systems can take you twice as far as the worst we've tested.

E-bike motor system reviews - discover our top pick and narrow down your e-bike search

What e-bike battery size do I need?

E-bikes come with different sizes of battery. To know how far it can get you on one charge, look for its capacity, which is measured in Watt hours (Wh). E-bike batteries typically range between 300Wh and 500Wh.

As a general rule of thumb, the larger the capacity the longer the range. 

However, this is also impacted by the motor the battery is connected to: for example, the same 400Wh battery may do 10 miles less if connected to a less efficient motor.

The size of the battery will also affect how much assistance the motor can give you when you need it.

If you live in a hilly area, or you plan on riding your bike on lots of hills, then it's worth opting for a higher-wattage battery to make sure it has enough juice to cope .

Does the bike have a replaceable battery? 

Lithium-ion batteries degrade over time, and after a few of years of heavy use, you might notice that it doesn't last as long, or take you as far, as it used to. In fact, it's common for a battery to have a much shorter warranty length than the rest of the bike. 

Because of this, it's incredibly important to pick an e-bike that has a replaceable battery. Otherwise the clock is ticking on the effective lifetime of your bike the moment you leave the shop. 

Most electric bikes costing over £1,500 have a replaceable battery, but cheaper bikes might not. Make sure you check before you buy, and also check the cost of replacement batteries. A replacement e-bike battery typically costs around £200-£500.

How to maintain an e-bike - our expert advice to make the motor and battery last longer


Other features to consider when buying an e-bike

Assistance levels

Different e-bikes have slightly different setups, but most will offer an equivalent of low, medium and high assistance modes. These usually equate to the motor matching your input, giving one and a half times your input, or doubling your input.

Display unit

The control display usually sits on the handlebars and allows you to adjust the assistance level as you go. In our tests we found some were clearer and easier to use on the go than others.

Frame size

One of the most common bike-buying mistakes is an oversized or undersized frame. It can ruin your enjoyment of a bike if you have to reach too far for the handlebars or you simply can’t find a comfortable riding position. 

Always test-ride a bike at your local bike shop before you buy one, and check manufacturers' guidelines to find the right frame size for you.

Brakes

The increased weight of e-bikes means you need a decent set of brakes. E-bike brakes are no different to the brakes on a regular bike. Depending on the type of bike you’re looking at, it will have one of the following braking systems:

  • V-brakes - common on touring and off-road bikes, they have easily replaceable cartridges.
  • Cantilevers - similar to V-brakes but they only have a cable between them, which means they’re less likely to get clogged with mud. A good option for off-road riders.
  • Caliper brakes - common on road or race bikes, they’re a bit smaller and lighter than V-brakes and cantilever brakes.
  • Disc brakes - increasingly popular in professional cycling, the main advantage of disc brakes is their increased stopping power in wet conditions.

Entry-level e-bikes are likely to have braking systems from brands such as Shimano or Tektro. SRAM and TRP are more commonly, but not exclusively, found on pricier e-bikes.

How to buy the best folding e-bike - tips and advice on what to consider if you want a bike that folds

Electric bike conversion kits

E-bike conversion kits can be purchased at relatively low cost and fitted to a standard bike to convert it into an electric bike. 

Prices start from around £400. Typically you get a front or rear wheel with an electric hub, a battery and a display unit to fit to your existing bike.

They’re relatively complicated to fit yourself, but can be a cheaper option than buying an entirely new bike.

First Look: Swytch e-bike conversion kit - get our first impressions

Electric bike brands and retailers

All of the major bike retailers in the UK, such as Halfords, Evans, Wiggle, Chain Reaction Cycles and Rutland Cycles, stock electric bikes. Any of these retailers or your local bike shop are a great place to start if you want to try different types of electric bike.

The majority of major bike manufacturers, such as BMC, Cube, Giant, Orbea, Raleigh, Scott and Trek, also now have electric bike ranges. There are also some electric-only brands that you might not be as familiar with, such as Cowboy, Gazelle, Haibike and Volt.