Hub motors - neo-powers.com come in two different types, say, geared and gearless. Gears provide leverage, enabling smaller and lighter weight motors to achieve greater output but also produce friction, noise and wear. Most modern geared hub motors are built very well and should last for many years. It may seem counter intuitive but geared hub motors do not add resistance when coasting. This is because they usually contain a freewheel mechanism that can unlatch from the axle and spin with little to no friction.
Moving on to the next motor type, gearless hub motors deliver smooth, quiet performance and are often considered “bulletproof” by shops due to their simplicity. Gearless hub motors rely purely on electromagnets and may not include a freewheel mechanism, because when the magnets are powered off, there is very little friction or magnetic resistance to overcome. Motors that do not freewheel are called direct drive and this actually enables regeneration.
Not all gearless direct drive hub motors offer regenerative braking or regenerative modes because you don’t tend to recoup much energy this way, although it can help reduce wear on brake pads. It’s a neat feature but it costs more to implement and adds complexity to the system.
Gearless hub motors may require a larger casing, in order to accommodate the magnets, and ultimately weigh more. This is of course a generalization because the technology has evolved to the point where some direct drive hub motors are quite small and lightweight.
So to recap, hub motors operate independently of the rider pedaling, they can be geared or gearless, can fit in the rear wheel, front wheel or even independently from the wheels and they can sometimes generate electricity. Some drawbacks of all hub motors include increased unsprung weight, which can reduce traction, limit efficiency and strain spokes and rims. They usually have just one gear setting that can operate at a faster or slower speed but cannot shift for improved torque or speed. They also tend to make wheels more difficult to service because they add weight to the wheel and require extra cables to deliver electricity and operation signals.