At E-Ride we sell bicycle conversion kits, as well
as fully assembled electric bicycles. This allows
customers to custom tailor their bikes to suit their
needs and fit their budget. When selecting an electric
bicycle you will want to consider weight at a premium.
Without the wide motorcycle tires and sturdy frames
of our scooters, bicycles are much more cumbersome
vehicles when overloaded. Range and speed are important;
but they come at the expense of greater weight. Start
by considering the distances you will need to cover
on your e-bike, you can minimize the weight while
still reaching a sufficient range. If you do not need
to travel far in your daily commute- or if you enjoy
pedaling and use the motor only as an assist- you
may decide that lead acid batteries are sufficient.
Lead acid batteries are much cheaper but much heavier,
providing less than a third the energy density of
lithium batteries. Once you have decided whether or
not your bike will need lithium batteries, you can
select the rest of the components- the frame, motor,
and controller.
Frame
- A choice that involves both form and function,
the frame you choose will determine the look of the
bike and the quality of the ride. The frame will also
add significantly to the weight of the bike; if you
want to keep your machine as light as possible and
aluminum alloy frame is the best choice. Most bikes,
like our Swift and Kuahara models, are welded frames-
the welds add to the weight and are a potential failure
point. Cast aluminum frames, such as the one on our
Caper model, are stronger and lighter. Almost any
bicycle frame, from road bikes to mountain bikes can
be modified to include an electric motor. One requirement
to keep in mind is there must be enough space between
the front or rear forks to fit the hub motor- usually
four inches is sufficient. To learn more about different
available bike frames contact any local bike dealer.
Motor - There are two basic types of electric
bikes: those with an external motor and those with
a hub motor. External
motor is used in a few bike models, like the Currie,
Lashout and Synergy. The recent trend in the electric
bike industry is toward the much more convenient and
efficient hub motors, so we will disregard all side
mounted motors and discuss further only hub motors.
In the following discussion, therefore, 'motor' means
'hub motor.'
For the purposes of this discussion, we will assume
that the motor, like all of ours, is built with high
precision from quality materials. We will discuss
only variances in hub motor design, specifications
and working characteristics. Since ultimately the
performance of the motor is dependent on a perfectly
matched high performance controller we will also assume
that, like ours, the motor is controlled with such
a controller.
The most common questions
we have been asked are: 'How powerful is the motor
?' and 'Does the motor recharges the battery?'. The
power of the electric
motor is certainly related to the power of the electric
bike. However the power of the hub
electric motor when used for transportation should
not be considered in the same way as the power of
a gas vehicle motor. The power of the electric bike
motor can be a 100% indication how much energy the
motor draws from the battery, but may be 60% indication
on how powerful is the e-bike itself. The most important
feature for electric bikes is the motor torque.
Torque
is very important since you carry a restricted amount
of energy in your batteries and can't afford to increase
the bike performance at the expense of the motor power only (as you can do with the fossil fuel engines).
So for optimized e-bike motor efficiency, the motor
should have maximum possible torque with the minimum
possible power. Greenwit Ltd has introduced Efficiency Index "Ebk" which is the
ratio of the hub motor torque towards the power of
the motor. In other words the higher the "Ebk",
the better the motor efficiency is. The most efficient
motor should have Ebk > 0.1 . How can we increase the "Ebk"? There are
two independent ways: by using strong rare earth magnets
or by increasing its speed and convert the
speed into torque with built in torque
converter. The first way, using strong rare
earth magnets, is used in 90% of the hub motors. The
second way was first used by the Hainzman motors and it is becoming popular for increasing the
"Ebk" value. Because
hub motor torque converters use planetary gears, which
are highly efficient, the increase of the torque
achieved by this method is tens of times bigger than
the losses they introduce. The integrated gearing
inside the motor allows a high torque initial start
because the motor starts at its efficient high speed
range immediately after the bike throttle is cranked.
The integrated gearing also allows the motor to work
more efficiently uphill when the speed of the bike
is low; the hub motor has conserved its high speed
momentum due to its torque converter. Another advantage
of the torque converter is that it allows the size
and the weight of the regular hub motor to reduced
and increases the torque immensely or the same power
consumption.
The other feature of the electric motor that we are
continuously asked is if the motor recharges the battery,
i.e., 'does it regenerate?' An electric motor 'regenerates'
by creating electricity when the motor spins in response
to an external force. If there is a load attached
to the motor this generation causes a big resistance
on the motor shaft. This resistance is a very useful
feature of electric bike motors and it is used for
electric braking.This regeneration as a power supply
for battery recharging is not very efficient and cannot
be relied on for recharging the battery. The regeneration
efficiency of an electric bike is 20-40% which means
that to fully recharge a discharged battery, one would
have to go downhill 3 or 4 times longer han it would
take to recharging a battery using a plugged-in charger.
This means that the rider would have to go continuously
downhill for 15 - 20 hrs for a full battery recharge.
More realistically, if the route your ride your bike
on has 20% downhill riding, you will generate enough
electricity for 3.3% of the whole battery capacity.
What is the disadvantage of the geared motors? Since
there is a gearing inside the motor, there is a free
wheel or roller clutch which eliminates the gear resistance
of the bike when coasting. This prevents the possibility
of the hub motor to be used for regenerative braking.
(This however applies for the current geared hub motors
available on the market, but doesn't eliminates the
possibility of combining the gearing with regenerative
braking). Considering the fact however that regenerative
braking for the e-bikes is mainly used for braking
rather than battery recharge because of its low efficiency,
the power, you will save from the geared motor is
much more than the power you gain from regeneration
1) Brushed motor
without gears.
Motors of this type have the lowest torque
compared to the other motors of the same power and
voltage . For 250 - 350W motors the torque ranges between 12-15Nm which is suitable for
hills up to a 4 degrees grade.
The advantage of these hub motors is that they
are very quiet (which some people would prefer). They're
also extremely durable and have the lowest cost. As
a general rule the higher the voltage of the power
supply, the higher the motor torque, and the higher
the speed. Their disadvantages can be partially offset
by using these motors on small wheels or powering
them with an at least 36V power supply. These motors are ideal for people who are not in a great hurry
and who travel over mostly flat terrain with moderate
hills. The power consumption of the brushed motors
is 10-30% higher than the brushless motors.
2) Brushed
geared hub motor
These motors have high torque and long life span.
The torque of 250-350W motors can reach 15 - 25Nm.
This is enough torque for handling of 8 -10 degree
inclines. Their torque depends on motor speed (Motor
RPM) and the gear
ratio of the built in planetary torque converter.
Ideal torque can be achieved with the fastest motors
and the lowest transmission ratio. If a high speed
motor and low gearing torque converter is used their
torque can reach 30Nm and their efficiency index Ebk
can be greater than 0.1 (Ebk > 0.1)
3) Brushless hub
motor without gears
This motor has higher torque
and higher Ebk than brushed gearless motors.
There output is similar tothat of the brushed geared
motors. For a 250-350W motor, the torque is 18-25Nm.
Compared to the brushed motors, there are no parts
to contact inside the motor, except its bearings.
With fewre parts to wear out, brushless motors therefore
last much longer. The most efficient brushless motors
have rare earth magnets inside. These motors come
as 36V or 48V. Usually 48V are used when more power
is required, like in the electric scooters. This lowers
the amount of electric current in the controller and
alleviates its cooling.
4) Brushless planetary
geared hub motor
Planetary gears spread out the load over the gears
and are well balanced. They
also provide the highest torque compare to all other
motors and have a long life span. Their efficiency
index is greater than 0.1 (Ebk > 0.1). Their torque can reach 30 - 35Nm for
250 - 350W motor. These type motors are excellent
energy savers and they are a new trend in the electric
bikes where the light weight is a main priority. They
can provide the same torque as a motor twice more
powerful and have the same range witha battery twice
assmall. Our Caper,
Uno
and Swift
electric bikes have all geared motors which
increases their torque and
reduces the battery drainage.
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