A Guide to Electric Bike Motors and Drive Types


There are various types of electric bike motors available on the market. There are two main types, which are hub drive motors and central crank drives. There are significant differences between the hub drive motor and the crank drives.


The crank drive is located in the middle of the bike frame, where the bottom bracket normally sits. Crank drives propel the bike via the chain with the use of the rear wheel gears. It is therefore a very efficient system because it can increase its own torque through the use of wheel’s cassette. To put it simply, it can enable the bicycle to climb up very steep hills.

But the system has some disadvantages as well. The main disadvantages are the added weight of the drive and a lack of a throttle. Crank drives are normally built as a pedelec, which means that the electric assistance works only when the rider keeps pedalling by rotating the cranks (pedals). Crank drive systems are also equipped with a torque sensor, which identifies the effort a rider exerts on the pedals. The higher the rider’s effort on the pedals, the more power is supplied by the motor and the faster the bike goes. To sum up, the crank drive systems are very efficient and are great for hill climbing. Because they work as a pedelec only the rider does need to keep pedalling to make the assistance work.


Hub Drive Motors and derailleur type gears

The hub drive motor is a completely different drive type from the crank central drive type. The motor is located inside the hub, usually the rear, which propels the whole wheel independently from the bike chain or cassette. Hub motor bikes can be powered by both a pedelec mode and a throttle only. When using throttle only no pedalling by the rider is required. This is in contrast to the crank drive systems where pedalling is needed for the electric assistance to work. Hub motors provide a great solution for those who would like to take a break from pedalling but still want their bike to keep moving and for those who want to use electric assistance while pedalling but don’t want to pedal as hard. Hub motors are suitable for different styles of cycling as users can change the mode from throttle only to pedelec mode at any time.

There are different types of hub motors, with the main types being direct drive only, and the ones using an internal gearing system.

Direct drive hub motors

The direct drive hub motors are very reliable and quiet but can be quite large and heavy. The direct drive motors need to be big in order to generate a sufficient amount of torque.

Geared hub motors

The geared hub motors have a different construction. The hub shell is a lot smaller and the motors weigh less, compared to the direct drive ones. The electric motor inside is a lot smaller but it is assisted by the internal gearing system that allows the generation of higher torque levels. Low weight and smaller size are an advantage of the geared hub motors. However it is normal for geared motors to generate some noise. The level of noise can vary, with steel gears motors making more sound than Teflon gears.

Brushed or brushless motor?

There are also two different types of electric motors – brushed and brushless. Generally, brushed motors are less reliable than the brushless ones. They need to be replaced after being used for some time, whereas brushless motors can often run for years without the need for any maintenance. Brushless motors are generally maintenance-free and their failure rates are very low. 


The battery on an electric bike is just as important as the motor. In recent years, new technologies are being used and improved performance through technical advances are now available.


When thinking of buying an electric bicycle, most people are not aware of potential problems associated with batteries, one of them being the high cost if a replacement battery is required. The battery is the most expensive part of an electric bike. Currently replacement batteries can cost between up to £700 for a new battery pack depending on the type, its chemistry, the bike model and other factors.

All batteries will have some degree of memory loss of their capacity over time and the number of recharge cycles. The memory loss will vary in different batteries with some cheaper batteries losing as much as 50% of capacity after just six months of use, where as a better quality one may last up to two years  while only losing a part of their capacity. The majority of high quality e-bike batteries should achieve around 500-800 recharge cycles before they will need to be replaced.

Power delivery is also key to battery types. A good quality battery will provide consistent power throughout it's life. However as it nears the end of useful operation the power to the motor will start to deplete especially on the hills. During climbing the motor normally needs a higher current in order to deliver more power to the motor. It is therefore important to highlight that not every lithium battery is equal. Warranty on the battery is usually a good guide to quality and usually have a two year warranty. The cells used inside the battery should be of a high quality and from a reputable manufacturer. 


BMS battery management system in lithium batteries has a role of a little computer that controls the battery performance. All lithium batteries in electric bikes are built up with a number of cells which are all connected. Because there are many cells in one battery, one central computer needs to control a power delivery between cells, check the cell balancing to make sure that the battery does not overheat and delivers the specified current. Again, it all comes down to the price, with the majority of cheap lithium batteries using poorly designed battery management systems. It is therefore important to ask the seller what type of battery management system is fitted into the battery. 


The controller is the type of computer responsible for power delivery between the battery and the motor. There are various types of controllers, which can be programmed in different ways. Some controllers can be programmed as e bikes  operated by twist and go only or pedelecs, requiring the rider’s input in order to provide assistance. Other controllers are much ‘smarter’ and can operate in both pedelec and e-bike mode.