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6 Oct 2021

Revealed: the secret to choosing the perfect electric bike

Looking for a cheaper, greener commute? Want to go further on your bike rides? An electric bike might just be the answer
Commuter in suit on electric bike

The recent petrol crisis has caused many of us to rethink how we travel, particularly on shorter journeys and daily commutes. Could an electric bike be the perfect alternative to traditional forms of transport?

With the ability to be 'refueled' from the comfort of your home, a great e-bike can get you to and from work quickly and efficiently, plus give you some exercise. You'll also be able to go further on your bike rides and power up hills in next to no time.

However, with so many e-bikes available, it can be hard to know which is best for you.

The secret is to concentrate on the thing that separates e-bikes from ordinary bikes: the motor and display. Manufacturers such as Bosch, Shimano and Yamaha produce e-bike motors and displays and sell these to e-bike brands to put on their bikes. Consequently, many e-bikes have the same motors.

Once you've identified which is best for you, you can narrow down your search to only those bikes that have your chosen motor and display combination, then test ride the final few to find your perfect e-bike.

Read on to discover our latest motor and display reviews, and the e-bikes that use them.

Best electric bikes - read all our e-bike motor reviews and discover the top e-bikes you can find them on

The latest electric bike motor reviews

Bosch Performance Line CX

Bosch performance line cx e-bike motor

Bosch is one of the most popular e-bike motor manufacturers. It has seven motors in its line-up, with the Performance Line CX being the most powerful.

Bosch says the Performance Line is perfect for both commuting and hilly terrain, but is this fact or fiction? We've tested the Performance Line CX motor with Bosch's Purion and Intuvia displays - the latter having a USB port so you can charge your phone while on the move.

To find out how it scored in our tests, read our full Bosch Performance Line CX review

Bikes with this motor include:

Shimano Steps E5000

Shimano Steps E5000 e-bike motor

Shimano is another big name in cycling, with the company making bike components such as brakes, wheels and gear systems, as well as e-bike motors.

The Steps E5000 motor recently received a software update, increasing its power delivery in 'normal' and 'eco' assistance settings.

It is also Shimano's lightest motor, which the company claims is virtually silent when operating.

We tested it with the SC-E6100 display, which comes with Bluetooth so you can use a third-party display or smartphone app while on your ride.

Does the motor live up to expectations? Read our full Shimano Steps E5000 review to find out

Bikes with this motor:

Giant SyncDrive Core

The SyncDrive Core has a Yamaha motor, paired with Giant sensors and software.

It has a smart assist mode that uses six sensors, including an accelerometer and slope detector, which combine to adjust the power of the motor to suit the terrain.

In practice, this should mean that there is no need to change to a different assistance level while cycling.

We tested the SyncDrive Core motor with the RideControl Charge display.

To discover if this motor is worth the money, read our full Giant SyncDrive Core review

Bikes with this motor:

Elops KM790

Decathlon Elops KM79 e-bike motor and display

The Elops KM790 rear motor is found on cheaper e-bikes sold at Decathlon.

The motor has three levels of assistance, and being a rear motor it pushes you forward, which feels more natural than being pulled forward by a front-hub motor.

We tested it with an Elops KM790 - a basic display with LED lights to show which assistance level you're on and the remaining battery.

But does being more affordable come at the cost of actually delivering the power you need?

Read our full Elops KM790 review

Bike with this motor include:

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How we test electric bikes

cyclist putting battery into e-bike motor

Manufacturers may give a mileage figure to indicate how long the battery on their e-bike will last on a full charge, but they often won't publish the weight of the rider or the conditions they are riding in.

Trying to compare range with another bike based purely on manufacturer specs is therefore almost impossible.

Folding e-bike reviews - we test individual folding e-bikes so you know which one's are easy to fold and light enough to carry

E-bike lab tests

At Which? we test every motor under the exact same conditions in our lab. By testing every e-bike in this way, our reviews are not only accurate but comparable across different brands.

In our lab tests, we keep the following constant:

  • Weight of the cyclist (70kg)
  • Frontal area and air resistance
  • Rolling resistance of the tyres
  • A constant speed of 15.5mph (on a slope of 6% gradient the speed is reduced to 11.2mph)

Each e-bike is tested on a flat road, a shallow hill (1.5% gradient), and a steeper hill (6% gradient), revealing a motor's true performance and range in different riding scenarios.

E-bike test rides

Our lab experts also take each bike out for several test rides and assess the motor using the following criteria:

  • The smoothness with which it delivers power to the pedals - some motors are noticeably juddery when delivering power
  • How well it accelerates from a standing start - some don't deliver power until after a few pedal revolutions, making it more difficult to get up to speed from a standing start
  • Noise - some emit an irritating whine, which can be distracting and ruin your cycling experience

E-bikes: everything you need to know - our expert guide to help you decide the e-bike features that are right for you

Prices last checked 6 October 2021