| A city car (or urban car) is a small, moderately powered automobile intended for use in urban areas. It is more substantial and faster than a
neighborhood electric vehicle ("NEV") and has four seats, unlike microcars which are two-seaters; they
are typically between 3400 mm and 3600 mm long. These cars have been sold in Europe since the 1960s, and now are an official car classification. Most mainstream manufacturers have one or even two
city cars in their lineup. Unlike an NEV, the city car's greater speed and occupant protection allow relatively safe operation in mixed traffic environments and in all weather conditions.
Car classification is subjective since many vehicles fall into multiple categories. Not all car types are sold in all countries and names for the same vehicle can differ by region.
battery wiring -
brake lever - the hand lever used to activate the brakes.
brushless motors : generally have 8 wires coming out of them. Three thick wires which are for motor power the windings). Three wires because the motors have 3 sets of windings in them and
hence are called 3 phase motors. The other 5 wires are for the hall effect sensors ( one positive power wire, one negative ground wire and the other three wires are for each phase of windings
which each have a hall effect sensor.)
brushed motors : usually have only two wires, one positive and one negative. They have carbon brushes which contact a rotating segmented drum which switches which coil is receiving current
from the battery.. Brushed motors are generally also 3 phase motor because they have three sets of windings.
commentator : rotating drum made from copper segments which switch the coil in motor which is receiving power at any time.
and hence maintain the revolving of the motor.
brushes carbon graphite) blocks which conduct electricity but are very slippery (low friction) so copper commentator segments will slide along without friction (well very low friction). Type of
brush used can influence efficiency of motor.
controller : The controller is a regulator that supplies power to the motor in accordance
with the throttle setting. The controller is the brain of the system, with connections from all other components (motor, batteries and throttle) connected to it.
current : the flow of electrons through a wire
electrons : very tiny packets of energy which can travel very quickly and easily through metals.
neodymium (rare earth) magnets: quite strong permanent magnets, usually look silver in color.
ceramic magnets: about 1/4 as strong as rare earth magnets, are generally dark colored grey to black. Electromagnetic Fields
: Electric fields are created by differences in voltage: the higher the voltage, the stronger will be the resultant field. Magnetic fields are created when electric current flows: the greater the
current, the stronger the magnetic field. An electric field will exist even when there is no current flowing. If current does flow, the strength of the magnetic field will vary with power
consumption but the electric field strength will be constant. emf : (electro motive force): force current produces as its
induced magnetic field interacts with permanent magnets magnetic field.
inductance: when current is turned off the collapsing current makes a collapsing magnetic field which creates a high voltage spike
back emf : is the current produced in a motor by magnets moving past coils, motor is acting like a generator. When current is applied from batteries it overcomes the back emf, unless motor
is rotating faster than top speed caused by battery current, then back emf is bigger than battery voltage.
Frame Size Frame size generally refers to a measurement of the seat tube. This
is measured from the center of the bottom bracket to somewhere near the top of the seat tube. Unfortunately, manufacturers disagree about where to figure the top of the seat tube, so the same
frame may have as many as 8 different size numbers attached to it, depending on the manufacturer
front fork - it attaches the front wheel to the bicycle.
Fork End - A flat piece of solid metal, with a notch or slot to receive a wheel axle. There is one at the bottom of each fork blade, and another pair
at the junction of the seat stays and chain stays. Lower quality fork ends are stamped from sheet metal; better ones are forged.
hall effect sensors : in brushless motors hall effect sensors replace the commentator. It is a method of switching which phase is being given current at any one time. Usually two phases will
have power at any given time. Hall sensors allow a small current to flow through them. This hall sensors are switched on/off as a north then south pole passes it. This very small current flowing
through them goes to a mosfet which in turn is switched on/off in sync with the hall sensors. The mosfets allow large currents to flow to the motor coils in a very precise pattern determined by
their location near the magnets.
head tube The front tube of the frame, through which the steerer passes. The length of the head tube gives a quick visual indication of frame size,
because it varies more, proportionally, with frame size than any of the other tubes
 hub:
central portion of bicycle wheel which spokes attach too.
geared motor: a motor inside the bicycle hub which is separated from the bicycle hub but causes the hub to rotate by use of gears.
resistance : copper wire has a certain resistance to the flow of electrons through it, this resistance is used to determine the number of turns of wire and thickness of wire used in a
motor.
slotted motors : Slotted motors usually have pilars of coils or copper wire wrapped around an iron core. These motors usually have the magnets and coils one inside of the other.
non-slotted (axial motors): these motors usually have an iron backing plate which the copper wire sits on top of in flat coils.
The magnets or the coils may be the stator or the rotor depending on motor design. These motors usually have the magnets and coils lying next too each other.
magnetic field : magnetic fields are created by electrons movements or positioning. Permanent magnet materials are surrounded by a
magnetic field permanently and is due to how the electrons line up inside the material. Temporary magnetic fields are created when electrons flow through a wire.
induced magnetic field: an induced magnetic field is created when electrons flow through a wire.
mosfets The metal-oxide-semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET), is by far the most common field-effect transistor in both digital and
analog circuits. A FET with an oxide coating between gate and channel is called a MOSFET (metal- oxide semiconductor field
effect transistor) The figure below shows the oxide, insulating the gate from the channel. As a result, the MOSFET has very high input resistance, higher than the JFET ; and as with the JFET, the
gate controls the main or channel current, Ids.
The field-effect transistor (FET) controls the current between two points but does so differently than the bipolar transistor. The FET operates by the effects of an electric field on the flow of
electrons through a single type of semiconductor material. This is why the FET is sometimes called a unipolar transistor.
non-geared motor: the outer casing of the hub is an integral part of the motor and usually this outer casing has magnets attached to it (it acts as a rotor)
freewheel: a. Geared hub motors: a mechanical device which allows the hub to rotate freely in one direction without causing the internal motor to rotate. This means pedaling is easy and coasting
has very little resistance.
b. Non-geared hub motors: freewheel refers to how much resistance the bicycle wheel has when rotating with no motor power (since the motor and hub are one and the same if the wheel is
turning the motor is also turning), there is no mechanical freewheel system involved
cogging : applies generally to non-geared motors and is the resistive force acting against rotation of the wheel, it is caused by the reaction of electrons in the iron core of a motor to the
rotating magnetic field of the magnets on the outer rim of the hub.
It will be felt as a small force acting against when you pedal when the motor power is off.
pwm (pulse width modulation): This is a method for regulating the voltage which a motor 'sees' from the batteries. See controller section for detailed explanation.
diodes: the devices allow electric current to only flow in one direction.
resistors: the devices determine how much electricity can flow through a wire..
capacitors: these devise temporarily store electrical energy
rotor: the rotating part of an electric motor
seat tube - the tube that supports the seat post.
seat post - it supports the seat.
SLA sealed lead acid battery
stator: the stationary part of an electric motor
 Throttle : The throttle regulates the amount of power supplied
to the motor via the controller. All the throttles use a linear hall type sensor and magnet inside them.
top tube - the upper tube that attaches the handlebar stem to the seat post.
voltage spike: can be associated with inductance when a current flowing through a motor is switched off. If a power wire to the motor accidentally disconnects or breaks while motor is under
load a large voltage spike may occur and can damage mosfets in controller circuit
saturation: the iron core of a motor can only absorb a certain amount of magnetic field, at a certain point it becomes saturated and this determines the limit of power the motor can produce.
windings : This refers to the copper wire in a motor which is usually wound around an iron core.
coils: coils and windings refer to the same thing, the copper wire in a motor.
iron core: the iron core of a dc motor acts to channel the magnetic field and makes the motor run efficiently. 3phase: most
electric motors are three phase, it is an efficient method for running a motor. It involves having three separate sets of copper windings in the motor. 3 phase effect discovered by Nichola Tesla.
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