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7 October 2021

Best electric bikes for 2021

Our rigorous lab tests reveal the UK's best e-bike motor systems, found on top bike brands like Halfords, Trek and Giant. Find the ones that can truly support you, letting you go further with less effort
SM
Sam Morris
Up-hill-ebiking

Electric bikes (e-bikes) are a fantastic way to rediscover a love for cycling, or extend your enjoyment into your later years. 

They don't come cheap though, and we've found that some will take you much further than others. Some e-bikes won’t even get you up a shallow hill, and will only take you 30 miles on the flat.

The best we've tested will have you climbing hills with ease and power you along a flat road for nearly twice as many miles.

Read on to discover the best motor/display combinations, and some of the top brand bikes that have them.

Why we test electric bike motors

The most important part of an electric bike is it's motor and display. If this performs poorly, then there isn't much point in spending the extra money that an e-bike costs over a traditional bike.  

While there are many electric bike brands, there are only a few manufacturer's that produce motors such as Bosch, Shimano and Yamaha. This means there are many electric bikes out there that use the same motor and display combinations. 

Our independent lab tests focus on this bit of the e-bike, allowing us to let you know which e-bike motors are the best. This will let you then narrow down your search to just those bikes that have the motor/display combo that you want. 

To help, we've suggested a small selection of bikes with each motor review, from the most popular brands amongst e-bike owners1. Most bike retailer sites let you filter your search by the type of motor.

Often the same bike is sold with a different motor at different retailers, so double check the specifications if you find one of the bikes mentioned here at a different retailer.

Like with any new bike, you'll want to try out a few options before you buy, as a bike that is comfortable for some may not be right for someone else.

Not sure if an e-bike is right for you. Our everything you need to know about e-bikes guide has you covered

Best e-bike motors for 2021

Below is a summary table of all the motors we've tested, so you can compare their score and star ratings.

Each one is found in a range of different e-bikes, so you can use these results to narrow down your search. For more detail on a particular motor click to be taken to it's full review, or read on to read the full reviews of all the e-bike motors. 

Only logged-in members can view our recommendations in the table below. If you're not yet a member, sign up to Which? today for instant access to this and all our reviews.

Motor & Display
Overall score
Display unit
Acceleration
Flat terrain support
Hill Support
Range on flat terrain
Last updated September 2021

Display unit how clear, easy to use, and functional is the display unit. Acceleration how powerful is the motors acceleration. Low rating is weak, motor may struggle is starting on a hill. High rating is powerful, motor will accelerate the bike even when starting on a hill. Flat terrain support how much support the motor provides when travelling at 15.5mph on flat terrain. The more it provides the higher the star rating. Hill support how much support the motor provides when travelling at 11.2mph on a 6% slope. The more it provides the higher the star rating.

Bosch Active Line with Purion display (400Wh battery)

Bikes with this motor includeRaleigh Felix Step-through Electric Hybrid (£1,900 at Halfords), Cube Export Town Hybrid One 400 (£1,699 at Pure Electric), Trek District+ 1 (from £2,200 at Evans Cycles), Kalkhoff Agattu 1.B Move (£2,299.99 at Rutland Cycling)

Bosch claim their Active Line e-bike motor is quiet, with smooth power delivery and perfect for an urban commute. It is also the recipient of the Red Dot Design Award 2017. Coupled with the minimalist Purion display, a bike with this combo looks brilliant on paper.

But is this true in practise? We put the motor through our rigorous lab tests and in-field test rides. To find out how the Bosch Active performs log in or join which? today.

Bosch Active Line Plus with Intuvia display (400Wh battery)

Bikes with this motor includeRaleigh Felix+ Nexus Hub Step-through Electric Hybrid (£2,250 at Halfords), Trek District+ 6 (£3,050 at Trek Bikes), Kalkoff Image 5.B Move 2021 (£2,899.99 at Rutland Cycling)

The Active Line Plus offers a higher torque than the Active Line form Bosch. In theory this means the motor should have greater acceleration and be able to support better on more demanding terrain. Bosch claims the Intuvia display can be read under all lighting conditions, and it comes with a separate control unit so you can keep your hands firmly on the handlebars while riding. 

But does the motor really deliver? To find out how the Bosch Active Plus performs log in or join which? today.

Bosch Performance Line with Intuvia display (500Wh battery)

Bikes with this motor includeTrek District+ 9 (£4,000 at Trek Bikes), Cube Touring Hybrid Pro 625 2022 (£2,899.99 at Rutland Cycling), Kalkhoff Image 5.B Move+ 2021 (£3,099.99 at Rutland Cycling)

Bosch says the Performance Line motor is their most versatile system, perfect for commuting, a fast countryside ride or traversing hilly terrain. Paired with an Intuvia display, which Bosch says can be read under all lighting conditions, this motor and display combination looks amazing on paper.

But did it deliver when we put it through our rigorous testing? Find out how the Bosch Performance Line motor performed by logging in or join Which? today. 

Bosch Performance Line with Purion display (500Wh battery)

Bosch performance line e-bike motor and purion display

Bikes with this motor includeKalkhoff Endeavour 1.B Move (£2,099.99 at Rutland Cycling), Cube Nature Hybrid EXC 625 (£2,599 at Pure Electric), Haibike HardNine 4 2021 (£1,999.99 at Rutland Cycling)

Bosch says the Performance Line motor is their most versatile system, perfect for commuting, a fast countryside ride or traversing hilly terrain. Coupled with the minimalist Purion display, a bike with this motor and display should be easy to use, with great hill support.

But did it deliver when we put it through our rigorous testing? Find out how the Bosch Performance Line motor performed by logging in or join Which? today. 

Bosch Performance Line CX with Intuvia display (400Wh battery)

Bikes with this motor includeTrek Rail 5 SX 500 (display not given) (£4,500 at Evans Cycles), Trek Powerfly 5 2022 (purion display) (£3,850 at Trek Bikes)

The Bosch Performance Line CX motor is designed for electric mountain bikes, with high torque to allow for powerful acceleration even while on a steep hill. Bosch claims the Intuvia display can be read under all lighting conditions, and it comes with a separate control unit so you can keep your hands firmly on the handlebars while riding. 

A bike with this motor and display should be easy to use, with great hill support.

But is this true? We put the motor through our rigorous lab tests and in-field test rides. To find out how the Bosch Performance Line CX faired log in or join Which? today. 

Bosch Performance Line CX with Purion display (600Wh battery)

Bikes with this motor includeScott Aspect eRIDE 920 (£2,999 at Pure Electric), Cube Reaction Hybrid Pro 500 2022 (£2,699.99 at Rutland Cycling)

The Bosch Performance Line CX motor is designed for electric mountain bikes, with high torque to allow for powerful acceleration even while on a steep hill. Coupled with the minimalist Purion display, a bike with this motor and display should be easy to use, with great hill support.

But is this true? We put the motor through our rigorous lab tests and in-field test rides. To find out how the Bosch Performance Line CX faired log in or join Which? today.

Elops KM790 with Decathlon Elops KM790 display (300Wh battery)

Bikes with this motor includeElectric City Bike Elops 120E (£749.99 at Decathlon)

The Elops KM790 rear motor is found on the city bike Elops 120E at Decathlon. It offers three levels of assistance, and the display lets you control the bikes lights.

Being attached to a sub-£1,000 electric bike makes this motor a tempting offer. But will it give you the assistance you’d expect form an electric bike?

To find out how the Elops KM790 motor performs log in or join Which? today.

Giant SyncDrive Core with RideControl Charge display (500Wh battery)

Bikes with this motor includeGiant Entour E+ 2 GTS 2021 (£2,399.99 at Rutland Cycling), Giant Entour E+ 3 Low Step Through (£2,199 at Pure Electric)

Giant’s SyncDrive Core may be a Yamaha e-bike motor, but it is paired with Giant sensors and firmware so in practice operates completely differently.

The motor has a smart assist mode which uses six sensors, including an accelerometer and slope detector, to deliver the power you want – no need to change to a different assistance level. The RideControl Charge has a micro-USB port for charging your phone, and offers five support modes. 

But will this motor/display combo give you the smooth ride you’re hoping for? To find out how the SyncDrive Core motor performs log in or join Which? today.

Shimano Steps E5000 with SC-E6100 display (500Wh battery)

Bikes with this motor include:  Gazelle Citygo C7 HMS 2021 (display not given) (£1,899.99 at Rutland Cycling), Ridgeback X2 (SC-E5000 display) (£2,699.99 at Ridgeback)

The Shimano Steps E-5000 is a centre-motor and received a software update in 2021. It is Shimano’s lightest motor, which it claims is virtually silent when operating.

The SC-E6100 display is large and offers wireless Bluetooth communication so you can use a third-party display or smartphone app.

But can this motor offer the support on flat and steep terrain, and provide the range you need?

To find out how the Steps E5000 performed log in or join Which? today.

Shimano Steps E6100 with SC-E6100 display (500Wh battery)

Bikes with this motor includeKalkhoff Image 5.S Advance 2020 (£3,099.99 at Rutland Cycling), Volt Regent OUT OF STOCK (£2,499 book test ride at Volt), Volt Infinity (£2,799 book test ride at Volt)

The Steps E6100 is a premium e-bike system from Shimano. They claim it is their most versatile system, saving 20% more energy compared to their E6000 motor.  The SC-E6100 display is large and offers wireless Bluetooth communication so you can use a 3rd party display or smartphone app. 

But did this motor system go all the way in our lab testing? To find out how the Steps E6100 performed log in or join Which? today.

Shimano Steps E8000 with SC-E8000 display (300Wh battery)

Designed for mountain biking, this motor claims to tackle steep trails, with a stable and smooth power delivery. The SC-E8000 display is compact with dynamic visuals. 

But is the display all style and no substance? Does the motor actually deliver when put to the test?

To find out how the Steps E8000 performed log in or join Which? today.

Suntour R250HP with Suntour ATS display (400Wh battery)

Bikes with this motor includeCarrera Subway E Mens (£1,099 at Halfords), Carrera Subway E Womens (£1,099 at Halfords), Carrera Crossfire Womens (£1,399 at Halfords), Carrera Crossfire E Mens (£1,399 at Halfords), Raleigh Array Crossbar 2022 (£1,595 at Pure Electric)

This rear hub motor from Suntour offers 60Nm of torque. In theory this means it should offer good acceleration. Plus the ATS display offers four levels of assistance and allows you to view data such as speed, mileage and battery level while riding.  

This motor is often found on more affordable e-bikes, but does that mean the motor is up to standard? Find out how the Suntour motor performs log in or join Which? today.

Folding Electric Bike Reviews - find a great e-bike for commuting

How we test electric bikes


All of the e-bike motor systems we test are set up on a rolling road in a lab and put through an array of tough tests designed to simulate real-life use. We use the same setup to test all the different systems, so that you can easily see how they compare.

How we calculate electric bike range 

Manufacturers may give a mileage figure on their electric bikes, 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 is therefore almost impossible. 

For our range 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 is maintained when the bike is up to speed
  • When the bike is on a slope of 6% that speed is reduced to 11.2mph

You won't find range figures for e-bikes that are truly comparable anywhere else.

Assistance levels

We conduct our range and incline tests on three separate power assistance settings:

  • 100% assistance - motor is putting in the same effort as the rider
  • 150% assistance - motor is putting in more effort than the rider
  • 200% assistance - motor is putting in twice as much effort as the rider

Different cycling terrain

Each e-bike system is tested on a flat road, a shallow hill (1.5% gradient), and a steeper hill (6% gradient). 

Many of the motor systems we've tested can not provide all of the levels of assistance described above on even a shallow hill, making them unsuitable for hilly areas.

Expert riding assessments

Each e-bike motor system is assessed for 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 systems don't deliver power until after a few pedal revolutions, making it more difficult and less safe for a rider setting off and getting up to speed.
  • Noise - some motors emit an irritating whine, which could be distracting and ruin your afternoon jaunt through the countryside.

Display unit

The display unit is rated for how easy it is to use, for example switching between assistance levels, and the visibility of the data it displays in various light conditions.


Prices last checked 07 October 2021

1 March 2021 Which? survey of 697 electric bike owners.