I am trying to interest the largest bicycle club in my area (Seattle), he
Cascade Bicycle Club, about the importance and future of electric bikes.
In July I wrote an article about the fun, practicality, and benefits of
e-bikes, and now I would like to provide information that would help them
purchase an e-bike or an e-bike kit. So I want to know if the information
that I give them is accurate. So if you see any errors in the presentation
below, let me know.
Thanks,,
Larry Gales,
Here is the article (limited to 600 words):
======================================================
In July I wrote an article in the "Courier" about the many advantages of
electric bikes, or e-bikes, and how they are becoming a mainstream form of
local transportation throughout Asia and Europe. I hope to encourage
people in this country to acquire e-bikes and so relieve us from the
problems caused by the near exclusive use of automobiles.
There are many aspects to consider when acquiring an e-bike:
o The method of purchase: buy a ready made e-bike or convert an
existing bike with a kit
o The odometer and battery state of charge display
o The power you need (typically 250 to 750 watts)
o The type and size of battery
o The type and location of the motor
o The wheel size compatible with an e-bike kit
o The weight of the e-bike, typically 15-25 lbs more than conventional
bikes, but note that with an e-bike, the weight only matters when
lift or carry it, so you can easily detach the battery, cutting the
additional weight to 8-12 lbs.
o The purchase cost and servicing of e-bikes
Here we consider only the type, control, and placement of the electric
motor in an e-bike.
o There are three main ways to control an e-bike motor:
- Pedelic: this multiplies the power you apply to the pedals,
typically by 25% to 300%. So the motor only operates when you
pedal
- Throttle: the motor starts when you press the throttle. You can
also pedal to add power or extend the range
- Both: many e-bikes provide both options
o There are two main types of e-bike motors:
- Mid-drive motor: this is a geared motor that drives the chain
wheel which in turns powers the chain that powers the rear wheel.
The main advantages are that the motor is isolated from the shock
and vibration of the wheel, and it operates in a way that is most
similar to the way a conventional bike works. However, it
requires frequent gear shifting which must be coordinated with the
motor controls
- Hub motor: this motor fits inside the wheel around the axle, and
is the most common e-bike motor. The main advantages
are that it greatly reduces the wear and tear on the
drive train as it powers the wheel directly, it usually eliminates
the need to shift (if the motor is sufficiently powerful), it
often enables regenerating braking which can restore
10-20% of the battery charge, and adds a 3rd braking option.
Note that hub motors mounted in the front wheel cannot use
pedelic control. There are two main types of hub motors:
* Gearless hub motor: this is powered by a ring of rare earth
magnets that are electronically switched on and off to turn
the wheel. It has no moving parts and lasts longer with less
(usually no) maintenance than geared motors, it is the
quietest of all motors, and enables regenerative braking.
The main disadvantages are that it is larger and
somewhat heavier for the same power as a geared motor, the
torque (needed for hill climbing) is about 20-30% less,
especially at very low speeds, for the same power rating as
a geared motor, and there may be a small amount of drag when
the motor is off.
* Geared hub motor: this uses planetary gears. It does not
cause any drag when the motor is off, has more torque and power
for a given weight than a gearless hub motor, but does not
(currently) allow regenerative braking. It is slightly noisier
than a gearless motor and requires more maintenance because it
has moving parts.
========================================================
--
Larry Gales
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