The Difference Between Mid Drive and Hub Drive Motors
Electric bikes are one of the fastest growing modes of transportation and it’s not hard to see why. They help riders go faster, further and longer. Because of their recent popularity, there are a wide range of styles, motor and price points from which riders can choose to suit their needs.
But there might also be some confusion by some of the specs, especially when it comes to motor positioning and how it affects performance. Because of this, it’s important to know the differences between the two main types: hub-drive and mid-drive.
A mid-drive motor is named because it’s located in the middle of a bicycle’s frame near the bottom where the cranks are located. The mechanisms required to coordinate the motor’s power with pedalling and shifting are a bit more complicated than hub systems and therefore it’s more important to be in the correct gear when riding an ebike with a mid-drive motor.
Depending on the programming, the shifting may not feel as smooth as an ebike with a hub motor. For example, if you don’t pedal with a smooth pressure you can experience surging as you ride.
Some people love mid-drive motors and for some circumstances they make sense. For example, avid mountain bikers prefer mid-drive motors for technical riding because the centre of gravity is weighted at the middle of the bike, which they’re used to from riding regular mountain bikes on trails. The ability to better control the motor traction also fits well with the variable terrain encountered when mountain biking.
In most cases, mid-drive motors require a specially designed frame to contain the motor in the centre. Almost in all crank motor options in the market such as Bosch, Shimano, Yamaha or Brose or Bafang, the controller is integrated in the motor, making it simple for OEM electric bike manufacturers. On the other hand, this integration makes the maintenance and repairs more of a challenge for end consumer.
- Pro: Efficient at a wide variety of speeds
- Pro: Can use gearing to alter target speed
- Pro: Can take advantage of gearing for climbs
- Pro: Places weight at the center of the bike
- Con: Produces driveline wear (chain rings and cassettes)
- Con: More complicated installation
- Con: Tend to be more expensive
- Con: More complicated, thus more prone to part failures (sprag clutches, drive gears, drive shafts, etc)
A hub motor is located on the rear hub of the ebike. It is completely sealed and self-contained and requires no additional maintenance.
A hub motor seamlessly delivers power where and when it’s needed, working independently of your pedalling and gear shifting. Overall hub motors end up being a smoother ride because you’re not having to worry about shifting as much and maintaining proper tension.
Hub motors can be activated by turning the pedals or using a throttle. The motor uses either a cadence or a torque sensor. A torque sensor gives you more power if you push harder. The cadence sensor simply detects when you are turning the pedals and the computer smoothly turns the motor on at whatever level of power you have selected. It doesn’t matter as much which gear you are in with the cadence sensor.
- Pro: Simpler to install
- Pro: Lower maintenance
- Pro: Efficient at typical on-road cycling speeds
- Pro: Can recapture energy through regenerative braking
- Con: Smaller hub motors don’t perform well on hills
- Con: Places a lot of weight directly within the rear wheel
- Con: Motor Kv locks you into one target speed range
- Con: Makes changing a flat tire (on the drive wheel) a PITA
Which Conversion Kit Is Better?
The hub-drive motor positioning causes no change to the basic design of the bike, which means a motor can be retrofitted to almost any regular bicycle with a hub motor and battery pack. A hub motor also gives flexibility and is relatively inexpensive. A geared hub motor is the best fit for most riders but there are a few instances where a mid-drive motor might be better, for example if your bicycle thru axles does not allow a hub motor or as mentioned before for rock jumping activities.
Mid-drive complex mechanism makes it more vulnerable against installation, alignment, transmission and usage. For that reason, you never see big brands such as Bosch, Shimano or Yamaha offer a mid-drive motor as a retrofittable conversion kit.
Is A Hub Motors or Mid-Drive Better?
Generally speaking, hub motors have proven to be more reliable and durable on electric bicycles. Even if your hub motor fails, in most cases you still have a regular bicycle to pedal back home; in contrary, failure in mid-drive system or bicycle transmission means you are stuck.
Performance-wise, for the casual rider or urban commuters, it doesn’t really matter, and the differences are relatively subtle. After a month or so, whatever system you are riding you will have adapted to and will be riding without a thought about sensors and motors. We recommend you take both types of motors out for a test drive and see which one you like the best.
The ebike market has changed a lot over the last couple of years. It wasn’t so long ago when hub motors dominated the market. Now, as a matter of mass production of high quality all in one integrated mid-drive motors, the majority of European and North American electric bicycle manufacturers have shifted from hub-drive to mid-drives due to many of the inherent advantages. This is a passage big part of the electric bike industry has selected to focus on their bicycle features and leave electrical challenges to integrated motor system providers.
Looking at North America’s population distribution, not many people would get access to Bosch or Shimano service centers for repair and service of their electric systems. For that reason, to develop our ENVO electric bicycle and conversion kits we preferred a less complex and more reliable geared hub motor system with modular components and external controller for DIY maintenance and repair to brings long term customer satisfaction.
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