The two options of electric motors that we offer on bikes that we sell here at Brevard Bikes are a mid-drive or hub-drive motor.  For the most part, these are the only two options that you will find anywhere.  The basic difference between the two is a hub-drive is in the middle of usually the back wheel (we sell a few bikes with hub-drives in the front and back wheels).  When the hub-drive gets power from the controller it begins to turn and uses the spokes to turn the wheel.

Mid-drive motors are always found in the middle of the bike between the pedals attached to the crank. Mid-drive electric bikes have become very popular in the last 3 or 4 years as they are the newer technology and generally provide a more efficient ride. Mid-drive motors also provide a more balanced ride because of their placement at the middle of the bike.

Comparing a Bafang 750W Mid-Drive to a Bafang 750W Hub-Drive

Torque

Hub Drive rated about 80Nm of torque

Mid Drive rated between 120-160Nm of torque

Gearing

Since a mid-drive motor is at the crank of the bike it can benefit from all of the gears that you might have at the rear of your bike.  Much more efficient way to use a motor.

Hub-Drive is basically a one gear option for your bike.

Speed

Higher top end speed using a mid-drive because of the efficiency of the gears.  Where hub drive basically can use just one gear because it's not as integrated into the drive train as a mid-drive.

Durability

Mid-Drive motors will generally outlast hub drive motors just because it is a more efficient way to use a  motor.  It all goes back to the gear ratio that a mid-drive can take advantage of that a hub drive can’t.  

Reliability

Hub motors don’t require a chain to be able to ride.  So, if your chain breaks you can still ride to where you need to go.  On the other hand, since hub-drive motors are putting lots of pressure on your spokes and rim, you should make certain that you have  very strong and durable spokes and rim.  You will probably find that you are changing spokes somewhat regularly with your hub-drive. motor.

Mid-Drive motors will very infrequently, if ever, break the chain on your electric bike. If you are putting a lot of stress on the chain with climbing, etc, maybe carry an extra chain in your back pack.  A chain just takes a few minutes to swap out. Whereas, spokes and rim repair with your hub-drive is something that you will most likely have to take to your local bike shop to have repaired.

Technology

Hub-Drive motors generally have cadence sensors. These offer the most basic type of pedal assist technology.  Cadence sensors measure how quickly that you are pedaling usually by placing a series of magnets around the crank arms.  The cadence sensor sends specific amounts of power to the motor on your pedaling speed and your selected assist level.

Mid-Drive  motors generally have torque sensors. They measure how hard you are pedaling…or, how much force you are applying to the pedals.  Torque sensors do a much better job of “understanding” if you are on flat terrain, carrying heavy loads, going up a hill, going downhill or starting from a complete stop. With a torque sensor, the motor’s power delivery is much more varied and dynamic than a cadence sensor. A well “tuned” torque sensor will provide you with a more seamless ride.  Whereas, a cadence sensor can be much more “jerky” by comparison.  Torque sensors also help with battery life as they are much more efficient because of their advanced technology.

Maintenance

Hub-drive motors generally require more maintenance than mid-drive motors. It can be difficult to remove the wheel and hub-drive from your electric bike.  Also, if you don’t get it back on correctly the performance of your e-bike can suffer.  So, if you are switching out tires regularly it can be problematic.

Mid-drive are sealed within the crank area and don't require much if any maintenance. Changing out tires is just like changing tires on a non motorized bike.

Price

The higher price for bikes with mid-drive motors generally come from the fact that the bike is specially designed so that the motor fits and responds accordingly within the frame of the bike. Because of this, you will pay more for a similar bike with a mid-drive motor as compared to one with a hub-drive motor.