Many people want to know which is better, a hub drive motor or a mid drive motor? The answer is the same as most questions: it depends! Each has pros and cons see below to help you make the best decision.
Hub Motor Pros
The biggest benefit to hub motors is unseen and psychological (See Psychology 101 below). Riding while assisted with a hub motor makes you feel like you are being pushed from behind, riding downhill, or riding with a tail wind. The ride is much more enjoyable.
Hub Motor Cons
The biggest downside to hub motors is their potential to overheat. If you are riding uphill for an extended amount of time or constantly going up and down hills, they will generate a lot of heat. They are definitely capable of handling hills, but this is why electric mountain bikes (designed specifically for rough mountain bike terrain) are mid drive motors.
Mid Drive Pros
Utilizing the gearing of the rear cassette, the mid drive motor can allow for a little more acceleration and top speed with a smaller motor. This will reduce the overall weight and improve the handling of the bike.
Mid Drive Cons
Besides the increased price, shifting and maintenance are a big problem. The torque of the motor eats away at the cassette and chain and you cannot shift under load. It is not possible to use a high powered mid drive motor without turning the motor off while shifting. Similar to using a clutch with a manual transmission car this makes riding more tedious and less enjoyable.
Because a mid drive motor accelerates the front chainring, it pulls the pedals away from your feet. Because of this it makes you feel like the bike is driving you, you are not driving the bike. With a hub motor the acceleration is independent of the pedals which is why you get the sensation of riding downhill. Bicycle traditionalists prefer hub motors for this reason as you still feel like you are actually riding a bicycle.