A lot of time and energy has been dedicated by those wanting to “sell” a certain type of drive system for Ebikes. The systems fall into two main categories: mid-drive motors and hub motors (which are further divided into front and rear). In this article, we will attempt to understand and explore the differences without “selling” either or as a solution that is far better than the other because, as in most aspects of life, the merits of each may prove to be more valuable in different situations.
Hub-Motor
The most common of Ebike motors, the hub motor is a very popular choice for Ebike makers and bike modifiers. The hub motor can be placed on the rear or front wheel and takes the place of a conventional bicycle hub.
The primary advantage of the hub motor is simplicity, which translates to cost effectiveness. The hub motor is an entirely contained drive system whether in is located on the front or rear, the motor maintenance requirements are low and replacement is typically as easy as replacing a tire on a conventional bike.
There are two main types of hub motors available:
- Geared hub motors provide torque while reducing speed. They achieve this by a motor running a set of planetary gears (the name comes from the fact that they spin around the main motor shaft like a small set of planets). The possibility of recapturing energy while pedaling is diminished through the losses in the gear train, however, they typically have a higher torque for applications where that is required. They can also be smaller in applications at similar torque to direct drive.
- Direct Drive hub motors are a motor built directly into the hub. The motor shaft is the axle so there is very little loss in the drive-train. They are quieter than the geared motors and considered more durable. This is especially true in applications with higher load and cruising applications where there is no wearing of internal gears to be concerned with, and no gears equals less parts to wear.
Another factor in hub motors is the physical location on the bike. While some specialty boutique bikes, such as hunting bikes or off-road bikes, offer both wheels driven, in most applications you will still need to choose between them.
- Front Hub Motors are mounted directly between the front forks. They provide an excellent weight distribution when applied in an application with a rear battery or a rider position that is farther back. They do represent a problem for traction BECAUSE they are on the lighter part of the bike. They can also represent a physical limitation of size when positioned in the front.
- Rear Hub Motors are the most common type of hub motor. While the weight distribution is better with a front hub, the transferred power and traction of the rear mounted motor typically outweigh the benefit created by weight distribution. Rear motors can create problems with spoke tension when a lot power is applied under a heavier rider.
Mid-Drive Motor
Mid-motors are considered the premium choice for an ebike motor and many of the ultra-high end makers have invested in both the building of the mid-drive system itself as well as incorporating them into ultra-premium product.
