Electric Bikes: everything you need to know
By Matthew Knight
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
Electric bikes (e-bikes) are becoming increasingly popular. They can make a hilly or long commute more manageable, get you further afield on leisure rides, or restore a lapsed love for cycling.
There are a few different types, and they each have their pros and cons, so read on for more on what to consider before you buy.
In this article:
- How do electric bikes work?
- Do you still get exercise using an e-bike?
- How heavy are electric bikes?
- How much do e-bikes cost?
- E-bike types explained: front vs mid vs rear hub motors
- Which e-bike battery size do I need?
- Other e-bike features to consider
- Electric bike conversion kits
See our best electric bikes for 2019 for our pick of the best e-bike systems.
Our tests reveal the e-bike systems that will go furthest before you need to recharge them, and have uncovered some that are completely unsuitable for hilly areas.
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.
As you pedal you can ask the motor to 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 and insure it like you would a scooter.
This doesn’t mean that you can’t go faster than this on an e-bike, only that the e-bikes 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 comparatively very quick when going uphill.
Yes. Any time you go out on a bike, e-bike or not, your heart rate will go up, you’ll breathe a little deeper and you’ll be burning calories. How fit you get is up to you.
E-bikes have different assistance levels that vary the amount of oomph the motor provides. If you haven’t ridden a bike for years, and you’re worried you’re too out of shape for cycling, 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 the reassurance of back up, should you need it, on longer rides.
An e-bike can be up to 10kg heavier than a standard bike. This is because of the extra components, particularly the battery, which can be quite large.
- Hybrid bike - approx 15kg
- Hybrid e-bike - approx 25kg
- Folding e-bike - approx 16-18kg
This shouldn't affect you too much while you ride, unless you run out of battery and need to pedal up a hill, but 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.
- Prices vary from £500 to more than £5,000
- Most e-bikes cost between £1,500 and £3,000
Front or rear-hub motor e-bikes tend to be cheaper than e-bikes with a mid-engine motor.
You'll usually pay more for a higher spec battery that gets you further on a single charge, too. We found higher powered batteries don't always translate to more juice though, depending on the motor they're paired with. See our e-bike systems compared page for our top picks.
There are thousands of different e-bikes available to buy in the UK. Mountain bikes, road bikes, town bikes, folding bikes and hybrid bikes all have electric versions.
Regardless of the type of electric bike you are 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.
Mid-hub motors tend to be more expensive, but we think they offer a smoother ride.
Front hub motors
These are positioned on the front wheel hub. They’re common on folding bikes and cheaper touring e-bikes (typically under £1,500).
- The motor doesn’t wear down the chain rings as it is directly powering the wheel, rather than the drivechain
- You can customise the gears to suit your riding style (eg if you prefer more choice of low gears).
- Bike balance can be an issue as 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 wheel pulls you forward, rather than pushing you, which can feel a bit jarring.
Rear hub motors
These are situated on the rear wheel hub. They also tend to cost less than £1,500.
- Rear power feels more natural than front hub power
- The motor shouldn’t wear down the chain as quickly as a central hub motor
- Easy to customise the gears.
- You need a specially designed rear wheel
- Tricky to remove the rear wheel for transportation
- Weight distribution can be a problem, especially if the battery is also located at the back and the bike doesn’t have front suspension. Nearly all of the weight - including the rider - is over the back wheel.
Mid hub motors
E-bikes with a mid-hub, or mid-engine, motor are typically a bit more expensive than other types. They do have some significant advantages though, including better balance and a more natural feel when riding.
- More balanced weight distribution
- 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.
- 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
- Drivechain can wear down more quickly.
Which electric bike motor system is best?
Unquestionably the motor is the most important part of an e-bike.
E-bike manufacturers tend to buy their motors from third-party suppliers. Brands such as Giant, Canon and Raleigh will fit out their e-bikes with motors from motor manufacturers such as Bosch or Yamaha and pair them with a lithium-ion battery and a digital control display.
We’ve tested nearly all of the 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.
Don’t be left with a motor that is completely unsuitable for the type of riding you have planned, head to our e-bike motor reviews to find out which is the best one.
E-bikes come with different sizes of battery, which typically vary between 250W and 500W.
The size of the battery will impact how far you can go on one charge, and how much assistance the motor can give you when you need it.
A 250W battery won't get you as far as a 400W battery on the flat, and it won’t be able to help you as much if the road starts to point upwards either.
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.
Does the bike have a replaceable battery?
Lithium-ion batteries degrade over time, and after a couple 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 warranty length much shorter 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 as well. Some can be almost as expensive as a new bike.
Lithium-ion batteries also degrade faster if they're stored in cold and damp conditions, like in a shed or a garage where a lot of people keep their bikes. An easily removable battery has the added benefit of the ability to easily store it separately to the bike, in a more appropriate location.
Different bikes have slightly different setups, but most will offer an equivalent of low, medium and high assistance modes. These usually equate to the bike matching your input, giving one and a half times your input, or doubling it.
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.
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 just can’t find a comfortable riding position.
Always test ride a bike at your local bike shop before you buy one and check the manufacturer guidelines to find the right frame size for you.
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 come with 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, or 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.
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 from scratch.
Electric bike brands and retailers
All of the major bike retailers in the UK, like 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 Giant, Orbea, Raleigh, Trek, BMC, Cube and Scott also now have an electric bike range. But don't discount some electric bike only brands that you might not be as familiar with, such as Volt, Haibike and Gazelle.
Ready to buy? Discover the best e-bike motor systems.