The propulsion is the heart of an e-bike. In general it is difficult to say which propulsion method/type is the best. In this context there is no „good“ or „bad“. It is rather the question of which requirements do you have on the pedelec.
Basically there are 3 different types of propulsion:
Propulsion concepts primarily differ in the attachment of the engine: on the front wheel, rear wheel or in the region of the bottom bracket bearing behind the crank. Each position of the propulsion has considerable effects on the road behavior of the pedelec. Does the e-bike have to be extremely stable while cycling or do you prefer an extremely maneuverable model? Depending on the position oft he propulsion, it could give you the feeling of beeing pulled or pushed.
No matter what type of propulsion is istalled in a pedelec, it is more important how the engine control is regulated. The sensor registers that you start pedalling and passes the information on to the controller. The controller is the actual control unit. It adjusts the battery and causes that power is provided to the engine by the battery. After power flows the pedal assist of the pedelec is more or less directly activated.
Cheap pedelecs, for example, only register whether you pedal or not. The pedal assist will not be evenly but a „jerky push“. Smarter sensors measure how much power the cyclist himself achieves while pedalling. Thereby the pedal assist adapts to the individual power of the cyclist and it can evenly be rendered. This is rather sensed as a gentle push and not as an uncontrolled „turbo-impetus“. The more exact and faster the sensors of an e-bike react to pedalling, the less delay of the propulsion and all the more pleasant and more harmonious it is to ride a pedelec. The best way to assure oneself of the quality and functionality of that steering is to do a test drive. You should take the opportunity and test several propulsion types so you can feel the differences and find the most suitable option.
The propulsion of bicycles with a mid-engine is located behind the bottom bracket bearing. Through an optimal weight distribution, propulsion block and mostly also the battery are close to the deep center of mass. Thereby the riding qualities of an e-bike are not affected and lead to an enjoyable riding experience. This propulsion type is most likely equal to a „normal“ and natural pedalling. A mid-engine is the most elaborate option. Since the propulsion is integrated in the frame, production costs are higher than those of other models and converting of a normal bicycle is almost impossible. Mid-engines are mid-price products and are often offered at a high price segment.
Advantages of a mid-engine
Disadvantages of a mid-engine
This type of propulsion is a hub engine which is built in on a rear wheel hub.
Most part of the weight is shifted on the rear wheel. The result is a firm hold that allows a sportily way of cycling and is especially advantageous on ascents and in wet conditions. Due to the needed cabling for control and engine, the removal of the rear wheel is a lot more elaborate unlike if you compare other types of propulsion. And actually only pedelecs with derailleur gears or hub gears with 3 gears are offered.
Advantages of a rear wheel drive
Disadvantages of a rear wheel drive
Removal of the rear wheel could be a lot of work
Control and cabling are often complicated
Could be interference-prone due to cable installation (rain, splashing water)
Limitation of type of shifting system (mostly derailleur gears)
Back-pedalling brake is only partly possible
Weight is very „rear heavy“ which could affect the vehicle dynamics
When you buy a bike with front wheel drive – the electric motor is placed on a front wheel hub. Technically speaking a front wheel drive is the easiest to build into a bicycle and it is compatible with any gear shift and back-pedalling. This is why cheap pedelecs are often equipped with a front wheel hub engine. Front wheel acceleration needs some getting used to, though.
Advantages of a front wheel drive
Most affordable option
Altering a standard bicycle is almost always possible
Easy removal of wheels
Any type of gear shift can be used
Free choice of rear wheel brake – back-pedalling brake is possible
Disadvantages of a front wheel drive
Visually thick front wheel hub
Long cable runs are necessary and could also be more interference-prone
Hub engines burden the bicycle frame and could lead to breakage of the frame
Greater engines could affect the steering
Low surface pressure compared to rear wheel – slipping away is more likely
Greater weight on the front wheel – steering could be complicated
Driving needs getting used to because the front wheel rather „pulls“. Cyclist is used to the push from behind.