Types of electric bike motors.

by Eugene Metreveli November 16, 2015

Lets try to find out which type of motor would be more suitable for different types of electric bikes.

Hub Motors

Hub motors were the first type of drive systems for electric bicycles to be patented and they continue to be popular today. Instead of trying to integrate a motor into the bicycle drivetrain (complimenting the gears and chain that the rider uses) hub motors stay completely separate.
Mass produced hub motors out of China have made a huge impact on the electric bike market. There are a large number of Ebikes available on the market today because of the invention of the electric hub motor. Because of hub motors, Ebike manufacturers are able to use just about any bicycle frame to turn it into an electric bike. For better or worse, almost any company can choose to be an ebike manufacturer thanks to the simplicity of hub motors.

Pros

Hub motors are produced in massive numbers in China, making them affordable.
With a hub motor, you can easily convert almost any bike to an electric bike.
There is a wide range of power options (250 watts to 750 watts and beyond).
Some direct drive rear hub motors provide regenerative braking.
Hub motors are readily available.
Hub motors have few moving parts, so they are quite reliable.
Hub motors are stealthy in their appearance and near-silent operation.

Cons

Hub motors are unsprung weight in the wheel, which doesn’t really make a difference on a city bike with no suspension.
Hub motors are not great mountain climbers. They have a tendency to “bog down” on long steep climbs. See mid drive motors for climbing long and steep hills.
Bikes that have a rear hub motor with a rear rack battery are back heavy and that can affect the handling of the bike.
The higher torque hub motors (generally the more powerful) need larger spokes and sturdy rims.

All-In-One Wheel Motors

Smart wheel The all-in-one electric bike wheels house everything in the hub or wheel; motor, battery, controller, etc.

Pros

In general they are touted as being easy to install or remove because it involves the replacement of either the front or rear wheel along with installation of a few other components.
They keep the looks of the bike pretty clean. Some people may not recognize that it is an electric bike.
Some of these systems have smartphone integration that provide a wide array of features: adjusting the settings, tracking rides, locking the wheel, etc.

Cons

Repairing and/or replacing components of the system may be more difficult when compared to traditional electric bike kits. The wheel may need to be sent back to the company for service.
Some all-in-one systems have just one size of battery pack. Some traditional electric bike kits have the option to increase the battery size for more range.
Housing the battery so close to the motor can expose the battery to excess heat that can affect its range and lifespan.

Mid Drive Motors

Mid drive motor This configuration is closest to the way motorbikes work. A mid drive motor powers through the drivetrain (transmission) of the bike which enables the motor to help with long & steep climbs and power up to high speeds on flat roads.

Pros

Mid drive systems are known for being able to climb long steep hills because they can leverage the lower gears of the bike and keep their rpm’s in an efficient range without getting “bogged down” like a hub motor. This is a good feature if you ride in areas that have consistently long and steep climbs.
These motors can also leverage the higher gears of the drivetrain to cruise along at high speeds on the flat or inclined roads.
Since the motor is at the cranks of the bike it provides for a low and centered weight distribution.
Removing the front or rear wheel is easy because there are no motor wires or hardware to remove (compared to hub motors).
Most mid drive systems use a chain, cogs, and derailleur drivetrain. Some systems are compatible with internally geared hubs and belt drives.
There is the ability for a mid drive system to use a throttle and/or cadence or torque sensor pedal assist.

Cons

Since the power is being transferred through the drivetrain of the bike there can be more wear applied to the drivetrain components (chain, cogs, derailleur, etc.). The higher power systems will add significantly more wear and those components may need to be replaced on a more frequent basis.
To keep the mid drive motor operating efficiently you need to be shifting the gears properly for climbing hills or cruising along the flats. If you are used to shifting the gears properly on a conventional bike then this is nothing new.
Some mid drive systems can sense when you are going to shift the gears and they will reduce the power for a smoother shift. There are some systems that don’t have these sensors and that can lead to abrupt shifts when the motor is applying full power.
A majority of mid drives have a single chainring which limits the gear range to a rear cogset or to the gear range of an internally geared hub. For most riding conditions this is okay because the motor makes up for the gear range that is missing and the gear range of a rear cogset or IGH is pretty wide these days.
Most of the popular mid drives systems are only available on complete e-bikes with specific frame mounts.

Friction Drive Motors

In general these motors have a roller that sits on the bike wheel and uses friction to transfer the power from the roller wheel to the bike wheel.

Pros

A friction drive kit can work on a wide range of conventional bikes and some kits offer quick installation or removal.
These tend to be relatively simple systems that may have the advantage of less things to go wrong.

Cons

Friction drive systems don’t work well in wet weather because the friction element diminishes.
Most systems don’t work well with really knobby off road tires.
Some of the friction drives are not as aesthetically “clean” when compared to other systems.

Conclusions

For city bikes which a meant to be used for every day commutes hub motored ebike would be a best choice.

We would leave Mid Drive motors for specialized and expensive ebikes, like mountain bikes of fat bikes.

All-In-One wheel and friction drive motors are most suitable for DIY enthusiasts how want to have an easy way to convert their conventional bike in to a modern ebike.

Some materials was used from http://electricbikereport.com/