Comparison of mid- and rear-engine in E-Bikes

Do you want to buy an e-bike but don't know whether to choose one with a mid-engine or one with the engine in the rear wheel hub? Find out how the two compare by reading the article.

You finally decided to buy your new e-bike but browsing through various websites, Facebook groups and looking through the many offers for sale, you don't know whether to choose it with the central electric motor or with the motor in the rear wheel hub ? What is the best solution for your needs?

To clarify your ideas a little we advise you to read this article where we explain the main features of both categories.

Comparison of mid-engine and rear hub motor

The main differences between the two types of engines are that the central motor is located in the middle of the bicycle frame, near the pedals, and transmits power to the wheels via the chain. È very powerful and offers a great autonomy but is heavy , mainly suitable for the more challenging routes such as mountain trails and off-road riding in general, and it is no coincidence that most electric mountain bikes are designed with this type of motor.

The motor in the rear hub instead is located inside the hub of the rear wheel (the central part of the wheel that acts as the fulcrum of the wheel, allows it to rotate and holds the spokes in place) and transmits power directly to the wheel. È lighter , guarantees great power e autonomy and is suitable for easier and less demanding routes such as the home-office-supermarket journey.

How the mid-engine works in e-bikes

It is located in the centre of the bicycle, in the frame, at the bottom bracket, where two bearings rotate the cranks and pedals, allowing the motor to intervene directly when the pedals are moved.

How does it work? It is very simple, with the mid-engine there is no delay between the movement of the pedals and the delivery of the motor power, which is self-regulating according to the force the rider applies to the pedals.

Bafang mid-engine in the iO InBicy e-bike
The Bafang 250W central motor of the multifunctional cargo bike iO InBicy

When cycling, the torque sensor in the motor detects the speed of the bicycle and the amount of power required to support pedalling. It transmits this information to the speed controller, which in turn adjusts the amount of current sent to the motor to ensure proper pedalling assistance.
It is particularly useful for high-performance e-bike because of its performance and autonomy, and because it offers great efficiency in energy use, avoiding power losses.

Advantages and disadvantages of the mid-engine

I advantages of the mid-engine in e-bikes are:

  • High power The mid-engine is very powerful, acts directly on the drivetrain and provides excellent pedalling assistance on steep climbs or more complex off-road trails.
  • High autonomy : the mid-engine is very efficient in energy utilisation, a medium-sized battery can provide a very high autonomy.
  • Impact resistance: the mid-engine, firmly fixed to the frame, is stable and resists jolts, potholes in the ground and vibrations very well, which makes it ideal for off-road routes.

The disadvantages of the mid-engine in e-bikes are:

  • Greater weight A mid-engine is heavier than a motor in the hub, so the bicycle may be heavier to manoeuvre.
  • More complex repairs The mid-engine is designed with more complex mechanics than a motor in the hub, which results in more demanding and costly repairs.
  • Pedalling resistance With the motor switched off, there is often resistance to normal pedalling, forcing the cyclist to work as hard as in intensive training.

Among our best mid-engine e-bike models: iO InBicy . The revolution Made in Italy of cargo bike .
Find out more!


How the motor in the rear wheel hub works on e-bikes

It is very light , compact e easy to accommodate, In fact, being positioned in the centre of the wheel, it reclaims valuable space in the frame. For these main reasons, the motor in the hub is particularly suitable for e-bikes that focus on lightness and practicality .

Motor in the rear hub of the Ahooga folding e-bike
The motor in the rear hub of the city e-bike Ahooga Folder

This engine category uses a pedalling sensor which allows pedalling without the slightest effort, especially on flat and asphalted routes.
How does it work? The motor is activated by the simple pedal rotation and transmits a constant power directly to the rear wheel without going through the chain as is the case with the mid-engine, allowing you to reach 25 km/h in total relaxation, without having to make any additional effort.
It offers a great thrust power It is less optimised in terms of energy consumption but delivers power directly to the wheel, without wearing out other mechanical components such as the transmission.
It is mainly suitable for urban use and for those who use the bicycle for simple routes such as urban routes, also for trekking.

Advantages and disadvantages of the motor in the rear hub

I advantages of the motor in the rear hub on e-bikes are:

  • Great performance It instantly applies force to give thrust to the wheel.
  • Less maintenance In contrast to a mid-engine, the engine in the hub wears out the mechanical parts much less.
  • Lower weight The motor in the rear hub is lighter than a mid-mounted motor, which means the bike is easier to manoeuvre. Perfect for ultralight e-bikes.
  • Simplicity of construction The motor in the rear hub is simpler than a central motor, which means that repairs are simpler and less expensive.
  • It's like a muscle bike When the engine is switched off, the ebike behaves like a normal muscle bike, without offering any pedalling resistance.

The disadvantages of the motor in the rear hub on e-bikes are:

  • Lower power The motor in the rear hub is less powerful than a mid-mounted motor, and can provide less pedalling assistance on climbs or very demanding routes.
  • Lower autonomy The motor in the rear hub is less efficient in using energy than a mid-mounted motor, a medium-sized battery can provide a shorter range, but this does not detract from the fact that some models achieve a range of over 70 km.
  • Difficulties in removing the rear wheel In the event of a puncture of the tyre or the inner tube of the rear wheel, difficulties may arise when replacing the tyre, especially if you are out of town or in the middle of a suburban route. Kits exist to facilitate this task.

Among the best performing and ultra-lightest e-bikes with a motor in the rear wheel hub: Ahooga Modular the cargo city e-bike designed for urban commuting.


Cadence motor or torque sensor motor?

A further difference between e-bike motors, whether they are central or in the rear wheel hub, concerns the engine power management which takes place through speed sensors .

There are two types of speed sensors, the cadence sensors ei torque sensors both with their own characteristics, pros and cons.

Let's see together what their peculiarities are and what they are best suited for.

Torque sensor

The torque sensor, also called an effort sensor or torque transducer, transmits to the system's control unit an immediate estimate of the thrust the cyclist exerts on the pedals.
What does it mean? Simple, the more you pedal, the more power is delivered, obviously depending on the selected pedalling assistance programme, therefore requires more effort than a cadence motor.

This type is preferred by the more sporty who wish to experience with their e-bike the experience of a muscular bicycle and only use pedalling assistance to eliminate excess fatigue, while still using the strength of one's own muscles to a great extent.

It is certainly very training, and is the preferred system for those who enjoy long rides and wish to contribute their own effort to the pedalling, without just being dragged along by the bike.

Cadence sensor

The cadence sensor however, unlike the torque sensor, once you start pedalling with your own leg power, delivers power in accordance with the assistance level graduation of pedal assistance.

The sensors transmit the movement impulse to the motor, which starts to deliver power according to the chosen setting: there are usually between 4 and 7 levels of pedalling assistance, and each one delivers more or less energy. No matter how much you pedal, it always delivers the same amount of energy as indicated by the assistance level.

This technology has the great advantage that the motor wears out very little, as it is subjected to less stress and is stressed in a measured manner, and it is also very suitable for those who do not want to work too hard and use the bicycle as an everyday means of transport.

Which solution to choose?

Both the mid-engine and the engine in the rear wheel hub are good, high-performance solutionsEach has its own specific characteristics and its own advantages and disadvantages, so the ideal is to choose the type of e-bike to buy according to the use you want to make of it. Simple and urban routes? The motor in the hub is the most suitable. Off-road and demanding routes? Middle engine.

The central engine is performant in many respects, suitable for both everyday and extreme situations; the motor in the rear hub is the perfect solution for e-bikes that make lightness their strong point and for everyday use for simpler, mainly urban routes, it is also excellent for leisurely rides in the countryside and out of town.

And for you, which is the best solution? Central motor or motor in the rear wheel hub?

If you have any doubts and would like to discuss them with a bicycle expert, please do not hesitate to contact us!


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