wire coils are fixed and the magnets
rotate. The brushless motor does not
need brushes (no wear and no dust from
the worn brushes to contaminate the
engine), but it does require controller
circuitry to operate.

Hub motor: A motor that is incorporated into the hub of a wheel and drives
it directly. The hub motor’s axle is held
fixed in either the front or rear dropouts,
and its shell is spun by internal electronics. Most modern electric bikes use hub
motors.

Direct-drive hub motor: Direct-drive
hub motors are the simplest type of
hub motor. The magnets are fixed on
the inside surface of the hub, and the
windings are permanently attached to
the axle. When power is applied, the
hub is made to rotate around the axle.

The advantages of a direct-drive hubmotor include quiet (often silent) opera-tion, few moving parts, and the abilityto regenerate power into the battery(because the magnets are always mov-ing over the coils). However, becausethe motor is always mechanicallyengaged, there is “cogging,” a drag thatcan be felt while coasting. Direct-drivemotors must also be larger (and usuallyheavier) than comparable geared hubmotors to achieve the same perfor-mance.

Regenerative braking: Sometimes
referred to as “regen,”direct-drive hub
motors are capable of recovering a
small amount of energy back into the
battery while the bike is coasting. When
active, the motor’s drag on the wheel
increases markedly.

Geared hub motor: These are hub
motors built with internal planetary
reduction gearing. In contrast to direct-drive motors, they can be smaller, more
efficient and produce more torque.

Geared hub motors are mechanically
disengaged from the bicycle wheel
when not powered, so they avoid the
coasting drag experienced with direct-drive motors. These advantages come
at a price; geared hub motors are more
expensive, can be noisy (for electric,

but still very quiet compared to any
internal combustion system) and have
moving parts that can wear out.

Front drive: A front-drive bike has
the hub motor in the front wheel. This is
rarely used on production e-bikes, but
is quite common for conversion kits.

Rear drive: A rear-drive bike has the
hub motor in the rear wheel. The vast
majority of production e-bikes with hub
motors are rear drive.

Center drive: A center-drive bike
mounts the motor or drive unit in the
center part of the bike’s frame. The
most modern center-drive units supply power to the bicycle chain, so the
motor gains the advantage of any available gear options from the rear cassette
and derailleur.

Controller: The “brain” of an e-bike.
Typically, the controller acts as a smart
connection between the other components on the bike: motor, battery, throttle (if applicable) and the pedal assist.

Pedelec: A chiefly European term
meaning an e-bike with only a pedal-assist function and a speed limit of 25
km/h. ■