Electric Bike Motors Explained

Trek Electric Bike

Electric bikes have really come into their own in the last couple of years thanks to advances in electric bike motors and batteries. A couple of bike manufacturers, most notably Specialized, are making their own electric bike motors but the vast majority of bike companies are using the same motors. So, you will find exactly the same electric motor being used on bikes from different brands and at different price points. In this guide we’ll take you through the main types of electric bike motor and look at the differences between the most commonly used brands.


Electric Bike Hub Motors vs mid-drive Motors

Electric bikes tend to either come with a hub motor or a mid-drive motor. Mid-drive motors sit where the cranks and bottom bracket are on a bike and drive the cranks and chain around. Hub drive motors sit in the middle of the wheel and drive the wheel directly. Hub drive electric bikes are cheaper but less efficient. Most of the electric bikes that we sell use mid-drive motors.


Electric Bike Motor Controls

Most modern electric bikes have motors which will automatically kick in as soon as you start pedalling. There is no throttle or need to press a button, you simply pedal and the motor works automatically.

On hub driven bikes the motor tends to be fairly on or off whereas the mid-drive motors have a more graduated power. With mid-drive motors the harder you pedal the more power the motor will put out. This makes riding the bikes feel very natural and intuitive as the bike will respond instantly to the effort you are putting in.

Although mid-drive electric bike motors will respond to the pressure you put on the pedals they will also normally have settings for the amount of power you want the motor to contribute. Bosch electric motors come with a series of modes from eco, through touring, sport and boost. Each level contributes more power from the motor but in exchange the battery life gets shortened.


Electric Bike Motor Power

All electric bikes in the UK are capped at 25kmph/15.5mph and they are not allowed to have a power output greater than 250 watts. With the maximum speed and power both capped the competition between manufacturers of electric bike motors comes down to how the power is used and the weight of the motor. One of the most useful figures to look at is the torque produced by the motors as this will give you a sense of the acceleration and raw power for climbing hills.


Brands of electric bike motor

The two most common systems found on the electric bikes that we sell come from Bosch and Shimano.

Bosch Electric bike motors – Bosch motors are used by Raleigh, Trek, HaiBike and Cannondale. Bosch currently have 6 different electric bike motors with the main ones being their Active Line motors designed for hybrid and city bikes, and their Performance motors designed for mountain bikes. The major difference is that the Performance motors put out a lot more torque (75nm compared to 40nm in sporty modes) and the Performance motors also have a higher maximum cadence. This means that the Performance motors can accelerate faster and give you more power to get up hills and over obstacles while the Active motors will give you a smoother ride.


Shimano Electric Bike Motors- Shimano are the biggest manufacturer, and best known brand, of standard bike gears and brakes. Their electric bike motors are known as the STEPS system which stands for Shimano Total Electric Power System. Shimano STEPS motors are used by brands including Raleigh, Merida and Whyte.

Like Bosch Shimano make different motors for urban and city use, trekking and mountain biking. As you would expect the Shimano STEPS system is designed to work with wider Shimano gear and brake systems. Their top end Di2 models come with fully automatic gears so your bike can change gear as and when it needs to.


Bosch v Shimano electric bike motors– which is best?

The rider experience on Bosch and Shimano equipped bikes is very similar. Both have motors where the power kicks in automatically and where you can set the level of assistance you want. Battery life is very similar and the top speed and power output are both the same. However, there are some clear differences.

The Shimano motors are the lightest on the market and current models come in around 2.5kg compared to around 3.2kg for the equivalent Bosch model. This is a pretty significant weight saving. However, the maximum torque on the Shimano STEPS motors is 50nm, much lower than the 75nm Bosch motors can achieve so you get less raw power for acceleration and overcoming obstacles. This is one of the reasons why the Shimano motors are more commonly used on hybrid and city bikes rather than mountain bikes.

The Shimano systems do tend to come with less modes. They normally have three modes compared to four or five on the Bosch motors making them less tuneable. Again this tends to mean that the Bosch motors are favoured for mountain biking as riders can tune the power they want to respond to the terrain.