Journal of Transportation Technologies, 2012, 2, 1-12 Published Online January 2012 (
Campus Mobility for the Future: The Electric Bicycle
Ian Vince McLoughlin, I. Komang Narendra, Leong Hai Koh, Quang Huy Nguyen,
Bharath Seshadri, Wei Zeng, Chang Yao
School of Computer Engineering & Energy Research Institute, Nanyang Technological University, Singapore
Received September 19, 2011; revised October 16, 2011; accepted November 6, 2011
Sustainable and practical personal mobility solutions for campus environments have traditionally revolved around the
use of bicycles, or provision of pedestrian facilities. However many campus environments also experience traffic con-
gestion, parking difficulties and pollution from fossil-fuelled vehicles. It appears that pedal power alone has not been
sufficient to supplant the use of petrol and diesel vehicles to date, and therefore it is opportune to investigate both the
reasons behind the continual use of environmentally unfriendly transport, and consider potential solutions. This paper
presents the results from a year-long study into electric bicycle effectiveness for a large tropical campus, identifying
barriers to bicycle use that can be overcome through the availability of public use electric bicycles.
Keywords: Electric Bicycle; E-Bike; Campus Transport; Personal Mobility
1. Introduction
The campus environment, especially that of the more
established universities, has entered the public consci-
ousness as being a haven for bicycle use [1]: not neces-
sarily for reasons of their environmental credentials, but
because their low cost suits the student budget. However
many university campuses are notorious for parking pro-
blems [2], and it may also be asserted that the fossil-fuel-
led vehicles affordable to students are likely to be among
the most polluting of their kind. Much research world-
wide has been conducted on electro-mobility solutions,
especially during recent years of increased awareness of
CO2 emissions and the environmental consequences of
profligate consumption of fossil fuels. However, the co-
mmon term “electric vehicles” has become almost syn-
onymous with “electric cars,” apart from some prominent
niche examples which will be explored. In fact, cars are
only one example of practical electric transportation.
Unfortunately electric cars tend to be expensive, mai-
nly due to the cost of the battery assembly. A four seater
electric car being used to transport a single person is also
wasteful of energy, although perhaps less so than with a
petrol engined vehicle. Electric cars require parking
spaces just like existing vehicles, and thus will not solve
campus parking problems. These vehicles are also costly
in terms of insurance (especially for younger drivers),
require road tax payments (or equivalent in different
countries), and usually require drivers to posses a valid
license. By contrast, bicycles do not require insurance,
attract no road tax and typically do not require a license
to ride in most countries. Furthermore, they are efficient,
environmentally friendly, and far more dense, when par-
ked and driven, than the equivalent rows of cars.
From experience, we know that at current oil prices,
fossil fuelled vehicles are more attractive than bicycles
for most users, but that bicycles are significantly cheaper.
Thus barriers must exist to the use of bicycles for many
potential riders. The premise of this paper is that many of
these barriers can be overcome by technological means,
at minimal cost, to create a usable form of transport for
campus use. It should be noted that the emphasis here is
on short journeys taken around a campus area, and per-
haps short commutes from home to campus. Longer dis-
tance travel presents a different problem: petrol and die-
sel vehicles tend to become more efficient and less pol-
luting per kilometre as distance increases [3], and a dif-
ferent set of alternative transport solutions should be
considered. Short journeys by petrol-engined cars are
especially polluting (particularly until the catalytic con-
verter reaches full operating temperature), and are a good
target for replacement by bicycle.
Apart from usage barriers, Section 2 presents other
studies related to campus bicycle use and electrical-po-
wer assist bicycles. Section 3 analyses the specifics of
the typical campus environment, as this relates to trans-
portation options, while Section 4 surveys international
transport legislation and proposes an electric bicycle so-
lution for campus use. Since the authors have been oper-
ating such vehicles in a restricted-public lending scheme
for more than a year, Section 5 reveals an analysis of
system effectiveness and identifies particular usage chal-
lenges, before Sect i on 6 c o ncludes the paper .
opyright © 2012 SciRes. JTTs
2. Literature Survey
2.1. Vehicles
The bicycle, in its present upright form, called a “safety
bicycle” and introduced by the Rover model in 1885, is a
relatively cheap method of extending the range, increas-
ing the speed, and improving the energy efficiency of
human powered transport. It can coast down hills, roll
easily along the flat, and make use of gearing to tackle
steep hills. Many bicycle alternativ es exist, ranging from
recumbent models to chunky off-road machines, however
the “safety bicycle” shape remains most common.
Electric bicycles, with more than a century of comm-
ercial history (the first patents for electric bicycles were
granted in the 1890s), have long been available, and
found adopted in small numbers in many countries. Their
relative lack of popularity until recently may be attrib-
uted to technological or economic factors (explored from
Section 2.2 onwards), ho wever the fact of their existen ce
means that they are already covered by legislation in
most countries (see Section 4).
In terms of personal electro-mobility alternatives, there
are a plethora of amazing inventions ranging from the
Segway, the Yike Bike, Ryno, various electric scooters,
skateboards, power skates, electric quad bikes and so on.
Ignoring the fossil-fuelled variants, recent alternatives
have been released which are powered by compressed air
[4], flywheel [5], fuel cell [6] and probably other unusual
power sources. However the vast majority of experimen-
tal machines use a combination of electrical motor and
battery. Battery solutions tend to be limited to the robust
but weighty lead-acid cells in cheaper or older systems,
through surprisingly few NiMH variants, to Lithium Ion
(predominantly LiFePO4 or LiMn2O4 based cells) in more
modern and expensive variants [7].
The Segway is one of the most imaginative and inno-
vative personal mobility solutions to have been devel-
oped in recent years, with a loyal following of users, and
several niche application areas. However the Segway has
not attracted widespread adoption on campus to date.
General Motors have used the Segway as the foundation
for their P.U.M.A. (Personal Urban Mobility & Accessi-
bility) project which effectively adds car-like features to
the Segway; a seat, roof and steering wheel. Whilst this
is exciting and extremely attractive from a technological
point of view, it leads to a very expensive transport solu-
tion, requires significant thoroughfare space, and may
require licensing for use in certain locations (for example,
even the basic Segway is not currently legal for use in
public areas within Singapore). Electric quad bikes are
likewise expensive, bulky to park and have few advan-
tages over an electric bicycle.
In fact, all of the devices mentioned are expensive,
certainly significantly more so than a standard bicycle,
and most work on the premise of simply adding a motive
power source to a bicycle-type system (or scooter/skat-
eboard/skates). However it is by no means certain that
lack of such power assistance is the main reason why
bicycles may not have been more widely adopted in
many campus environments. Thus, adding motive power
alone may not lead to the more widespread adoption of
electric bicycle-type transport.
2.2. Barriers
Obviously, many potential campus users of personal ele-
ctric mobility vehicles (PEMV) have no effective choice
apart from fossil-fuelled vehicles at present [8], usually
due to commuting distance or traffic conditions. How-
ever it is possible to envisage a park-and-ride type sch-
eme where a large car park on the periphery of a campus
allows commuters to park, pick up a PEMV and use this
for inter-campus transport. Campus occupants who need
to attend a meeting elsewhere on a large campus, may
consider using some type of PEMV, if it were available.
In fact, studies (conducted for traditional bicycle use),
show that a very positive correlation exists between pro-
vision of cycling facilities, and the public acceptance of
their use, in terms of adoption by potential users [9].
Unfortunately, even when excellent cycling facilities
exist, a number of potential users prefer to drive or em-
ploy other means of transport. These barriers to the adop-
tion of cycling have been investigated by a number of
authors over the years. Perhaps the definitive survey of
these barriers is that compiled by Cleland [10], in which
results from several earlier surveys are collated and pre-
sented. For convenience, the most useful of these surveys
have been analysed here in Table 1 along with some
more recent survey data [11-13]. Various reasons are
listed along with the identified proportio n of respondents
who give those reasons. The methodology for each sur-
vey differed, so the bottom row of the table indicates
whether respondents were able to select only their pri-
mary reasons, were allowed to list multiple reasons or
where given a free choice of answers. Less popular an-
swers are were not captured in the table.
Since there is little correspondence between survey
questions, and in some cases wide variations in the pro-
portion of respondents citing a given reason, some inter-
pretation is necessary. In his study, Cleland matched the
top three reasons [10]. However in Table 1, it is rea-
sonably clear without further ranking that some factors
are more prominent than others as barriers to cycling:
Lack of cycling facilities (including cycle paths, ac-
cess to showers at work, and storage areas);
Perceived danger (especially from other road-going
The weather (particularly rain);
Distance/time issues;
Copyright © 2012 SciRes. JTTs
Copyright © 2012 SciRes. JTTs
Table 1. Reasons given for not cycling, compiled from a number of different surveys (with different objectives, methodologies
and question emphases). The reade r is strongly advised to refer to the original published studies before comparing quantita-
tive values across columns. An empty cell indicates a question that was not included in any particular survey.
Salzburg NHTSA Davies SnelsonAA Cincinnati Sydney Jackson Auckland Wellington
Reference [11] [10,12] [10,14] [10,15][10,16] [13] [10,17] [10,18] [10] [10,19]
Lack of
facilities 22.6% 55% (lanes)
27% (showers)
22% (storage)36% 41%
18% (lanes)
13% (storage)
10% (shower s)
Per c e i ved d a n g er 26.2% 3.4% Y 11% -
17% 11% 40% 32% 23% 12%
Weather 13.0% 8.2% Y 52% 10% (rain) 6%
Too far 10.7% 22% Y 3%
Time issues/
too busy 5.1% 16.9% 31% 22% 7%
Too much
effort 2.8% Y
17% (age)
8% - 16%
(effort) 8% 19%
(hills) 0% 17%
6% (hills)
5% (age)
Limited carrying
capacity 8.8% 26% (items)
13% (passengers) 2%
Don’t enjoy
it/comfort 3.2% 2.6% 41%
No bicycle 26% 13%
vandalism Y 10% 28%
traffic Y 7% - 16%7%
Out of % for each
(1 allowed)
% for each
(1 allowed)
Y/N to
reasons Unclear
for each
(1 allowed)
Percentage for
each reason
for each
(1 allowed)
Percentage for
each reason
for each
(1 allowed)
The effort required (particularly relating to hill clim-
Much research has been conducted on some of these
points, including the health benefits and risks associated
with bicycle riding [20]; with most studies concluding
that the health benefits of regular cycling exercise out-
weigh the dangers of sensible bicycle use for short-dist-
ance transportation. City planners have also long consid-
ered the provision of cycling facilities, and the impact of
this on usage patterns [8,21].
It is evident that many city and campus planners have,
in recent years, emphasised facilities for bicycle use. Cy-
cling is generally promoted worldwide as a sensible and
sustainable transport choice for campus and city comm-
uting. As fuel prices co ntinue to increase, and with grea-
ter public awareness of environmental sustainability, rates
of bicycle use should rise.
3. Analysis of Campus Environment
University populations (where students may live on or
near campus) tend to involve less commuting than is the
norm [2] in other communities, and thus in many cases
already tend to have a higher proportion of bicycle use
than general society [1]. Flat campuses in dry areas tend
to be the most cycling-friendly and cycle paths and racks
(especially racks with security or in locked and fenced
areas) encourage cyclists [1]. In addition, the image of
cycling being healthy and “green” and of course the fact
that it is relatively inexpensive, have traditionally con-
tributed to large-scale use of bicycles on campus. These
are all positive reasons for using bicycles.
There are also negative reasons that count against
driving (and thus implicitly encourage cycling), such as
parking difficulties and costs (Salzburg reported more
than double the number of cyclists a week after intro-
ducing parking charges [10]), the expense of purchasing,
road taxing, maintaining and fuelling a car. It may also
be that students are more environmentally conscious than
the general population, and thus more likely to reject
polluting and energy-inefficient means of transport.
Campus environments also exhibit strongly correlated
transport flows. In Nanyang Technological University
(NTU), Singapore, for example, lectures begin half past
the hour from 8.30am until 6.30pm, and end at twenty
minutes past the hour. There is thus a ten minute window
of large-scale movement as a significant proportion of
the 33,000 students and more than 5000 staff move be-
tween lecture, laboratory and tutorial locations, or travel
to one of the 18 canteens on the main 200 hectare (almost
500 acre) campus. Public transport entering the campus
is overwhelmed, especially at peak times from 8am to
perhaps 9.45am: car park entrances have queues of cars,
and parking spaces become scarce.
The consequence of the correlated people movement is
that campus transport facilities must cater for a peak of
activity that is many times greater than average activity:
naturally reducing tran sport efficiency. It also means that
there will be concentrations of people, cars and bicycles
near to food and beverage facilities at those times, and
particular concentrations in the vicinity of teaching fa-
Finally, the nature of a campus is that one authority
exercises control over planning, building, transport and
parking provision. Unlike a city or a suburban neighb-
ourhood, cohesive planning and action are generally much
more easily possible.
4. An Electric Bicycle Solution
Up to this point, we have carefully analysed the use of
bicycles on campus, presenting and analysing survey
results that attempt to explain barriers to greater adop tion
of the bicycle. If this data is then matched up with some
of the characteristics of the campus environment, it is
possible to propose technical, planning and procedural
solutions that together should encourage the greater ado-
ption of bicycle transport. This is the focus of the re-
mainder of the paper.
4.1. Legal Framework
Firstly, however, it is necessary to work within the bo-
unds of legislation. Most countries differentiate between
bicycles and motor vehicles, with the latter requiring
road tax, insurance and possibly an up-front purchase tax.
Bicycles may be fitted with electric motors, and still be
classified as bicycles, provided certain provisions are
made, primarily in terms of the maximum motor power.
Fitting a motor of greater power would result in a reclas-
sification of the machine as a motor vehicle. Table 2
surveys the maximum legal power allowed for bicycles
in various territories. Notably China [22]—the manufac-
turer of almost all electric bicycle components, and
probably the largest user of such vehicles—does not ap-
pear to have clearly defined national rules in this regard,
and Hong Kong is absent from the list since such vehi-
cles are totally prohibited in Hong Kong territory.
Most countries stipulate a maximum speed above
which motor power must cease, ranging from 24 km/h in
Japan up to 32 km/h in Canada and the USA [23]. Most
countries also require the machines to resemble normal
bicycles and be fitted with pedals. Some countries allow
three-wheeled (or even four-wheeled) electric bicycles, a
few such as Singapore, specify two-wheeled use only.
Table 2. Maximum power for electric motor assisted bicy-
cles in various countries (constructed primarily using data
from [23]).
Country Motor power output
Australia 200 W (currently t abling
legislation to move to 250 W)
Canada 500 W
Europe 250 W
India 250 W
Japan 250 W
New Zealand 300 W
Singapore 200 W (note potential shift to
250 W in the near future)
United Kingdom 200 W in UK law overridden by
250 W in European legislation
United States of America 750 W
The issue of pedelec is interesting: European and Sin-
gaporean law in particular require a pedelec: when pow-
ered, the motor must turn on within a certain time after
the pedals are operated (such as one revolution of the
pedals), and must turn off within a certain time after the
pedals have been released (such as the equivalent of a
quarter of a revolution at the original speed). This gives
rise to the electric assist bicycle, the type of machine that
requires a rider to contribute some effort to the motion,
but allows the motor to assist to a certain extent.
4.2. Motor Type and Placement
Most modern electric bicycles employ brushless DC mo-
tors, usually flat hub mounted assemblies consisting of
permanent magnet rotor and fixed armature coils ener-
gised sequentially by a motor controller. This arrange-
ment means that brushes and commutator are not req-
uired, leading to potentially higher motor reliability. Ta-
ble 3, listing typical technology choices for electric bicy-
cles, also notes that brushed DC motors are sometimes
used (they may be of lower cost).
Hub mounted motors may be placed on either front
wheel or rear wheel hub, as shown in Figures 1 (a) and (b).
Direct drive systems will power the bicycle directly, and
must cope with a wide range of speeds and conditions,
whereas geared motors (usually employing planetary
gearing) may allow greater torque at low speeds, and are
better able to be adapted to use with different bicycle
wheel diameters. Front wheel direct drive allows power
to be applied to front wheel (through motor) as well as
rear wheel (through pedals), providing a very stable
power transfer arrangement.
Although hub-mounted direct drive BLDC systems are
most common, several chain drive variants exist, either
using the existing bicycle chain in-line with the pedal
chain ring (the motor normally mounted behind the ped-
als), or utilising a separate chain attached to the pedal
Copyright © 2012 SciRes. JTTs
Table 3. Typical technology choices for adding electric po-
wer assist to a standard bic ycle frame.
Motor Placement Battery Control Motor type
Front wheel (hub) Lead-acid Pedelec
(magnetic) Brushless
Above front wheel (NiCd)/NiMH Pedelec
(torque sensor) Brushed DC
In front of pedals LiFePO4 Throttle Other (incl. AC)
Above pedals LiMn2O4 Simple on/off Gearing
pedals Fuel cell Sensors Through
bike gears
Rear wheel (hub) Super-capacitor Speed
(wheel rotation) Direct hub
drive (front)
Above/in front
of rear wheel Wheel size Cadence
(pedal rotation) Direct hub
drive (rear)
Controller small
(14", 16") Battery voltage Planetary ge ar e d
Regenerative medium
(18", 20") Torque
(at crank) Separate
chain drive
Non-regenerative large
(26", 27"
and 700C)
(at hub) Friction drive
to tyres
(a) (b) (c)
(d) (e) (f)
Figure 1. Typical electric bicycle motor mounting points (a)
front and (b) rear hub; (c) front and (d) rear friction drive;
(e) chain drive in-line with derailleur; (f) chain drive to se-
parate chain-ring.
chain ring. In both cases, a free-wheel mechanism must
be provided to prevent the motor from spinning the ped-
als—something which could result in injury to the rider.
The normal solution is to provide a free-wheel between
the pedals and the pedal chain ring, thus the pedal chain
ring can rotate and b e driven freely by electric motor, yet
the pedals remain stationary.
Apart from hub mounting and chain-drive systems,
friction drive has, historically at least, been a common
drive system for powered bicycles. This involves a motor
mounted above either the front or rear bicycle wheels
powering a drive wheel in contact with the tyre. Several
decades ago, small internal combustion engines would sit
in the same location. These could often be flipped up-
wards to take them out of contact with the bicycle tyres
when not in use. Each of these drive systems is shown in
Figure 1.
In general, geared motors allow the flexibility of chan-
ging the torque/speed relationship (either fixed, as in a
planetary geared system, or adjustable through the bicy-
cle’s own gearing), but suffer from greater wear and re-
duced transmission efficiency. Brushless motors are most
powerful (weight-for-weight), but more difficult to con-
trol than brushed motors, thus leading to more expensive
control systems.
4.3. Frame Issues and Wheel Size
Standard bicycle frames need to be able to accommodate
the extra mass of electric bicycle components (especially
battery), but also must have space for mounting the mo-
tor, controller and battery. Common locations for batter-
ies are on some kind of rack above the rear wheel, be-
tween the rear wheel and seat post, below a crossbar, or
above the front wheel. At least one electric bicycle con-
version kit locates batteries as panniers carried either side
of the re ar wheel. V ar iou s op tio n s ar e sh own in Figure 2,
and this issue will be discussed more fully below in Sec-
tion 4.5.
Chain-drive motors tend to be large enough that the
bicycle pedals have to be moved further apart than is
usual to avoid the motor from obstructing normal pedal-
ling motion. In these systems, the need for an extra chain
(in some cases-as different arrangements do exist), and a
chain-ring freewheel, also tend to increase the distance
between pedals.
Hub motors require a certain hub clearance of typi-
cally 110 mm: that is the distance between the forks to
accommodate the motor (and maybe more if disc brakes
are to be fitted). 110 mm is fairly standard, except on
smaller frames where the front fork clearance may be as
low as 65 mm or 70 mm. It should also be noted that, due
to the large shaft torque, hub motors above about 200 W
should not be used on aluminium forks. For this reason,
some hub motor manufacturers recommend that a torque
arm be fitted to hub motors.
Bicycle wheel size, for pedal powered bicycles, is of-
ten conceived primarily as an issue of comfort and rider
(a) (b) (c)
(d) (e) (f)
Figure 2. Typical electric bicycle battery mounting points,
(a) above the rear wheel; (b) below the crossbar; (c) as rear
panniers; (d) behind the seat post; (e) above the front wheel
or as front panniers; (f) built into the frsame or wheel.
Copyright © 2012 SciRes. JTTs
acceptance, however for an un-geared direct drive hub
motor, a smaller wheel gives greater torque: 40% more
for an 18 " wheel over an d above a 26 " wheel. Th is is im-
portant for hill-climbing ability, but co nversely a smaller
wheel driven in the same way (in terms of revolutions
per minute) will achieve a lower maximum speed. How-
ever, since maximum speed is restricted by legislation in
many countries, this may not be a significant limitation
in practice.
4.4. Controller Types
Although there are many research and technology issues
related to motor controllers, to the end-user they can be
classified as either allowing regenerative braking or not
(see Table 3). A regenerative braking system, detecting
the rider applying brake pressure, will operate the motor
as a dynamo, converting mechanical rotation into power
[24], reducing the kinetic energy of the vehicle. A cont-
roller that supports regenerative braking is likely to be
slightly more costly than one that does not. Anecdotally,
the regenerative controllers also tend to be slightly less
efficient in terms of maximum motor power output.
One particular problem with regenerative systems is
imposed by the charging regime for whatever battery
technology is in use: for example the maximum rate at
which the battery can be recharged. This is a particular
issue for the popular Lithium Ion batteries, which have
stringent charging requirements, and results in a constant
retardation force being applied during regenerative brak-
ing. Support for variable retardatio n is an active research
topic [25].
4.5. Battery Type and Placement
As listed in Table 3, several battery technologies are
available for powering electric bicycle motors. Of the
choices given, Lithium Ion cells offer the best power-to-
weight ratio, although they suffer from regenerative
braking issues (as mentioned in Section 4.4), and may
potentially be dangerous in the event of an accident. Su-
percapacitors are an interesting research area that may
well be usable for fut ure sy st ems.
Whatever battery technology is used, the power source
may well be the heaviest single component of an electric
bicycle. The potential placement locations were briefly
surveyed in Section 4.3, however it should be noted here
that battery location can significantly influence the cen-
tre-of-gravity of the machine, and contribute to the feel-
ings of stability, or otherwise.
Finally, the batteries listed in Table 3 must be re-
chargeable in some way: either being removed from the
machine and attached to a charger, or the entire bicycle
connected to a charging attachment. Complete removal
allows the possibility of swapping a discharged battery
for a fully charged one. Some machines, often home-
made ones, have solar panels mounted on them, or solar
panels attached to a trailer for recharging (which may
also house a battery).
4.6. Safety and Security
In terms of rider safety, of course wearing a helmet is the
most obvious and effective safety precaution [26]. The
relationship between motor power and safety is a com-
plex one, primarily related to increase in speed, but also
in increased weight. This area has been well studied by
the New South Wales Centre for Road Safety [27]—the
conclusion is that, at least for smaller motor powers (250
W and below), there is little correlation between safety
and motor power.
The larger mass of electric bicycles due to motors
(which weigh around 5 kg for a 250 W hub BLDC), bat-
tery (again around 5 kg for an 8 Ah 24 V Lithium Ion)
and other components, will require better brakes than a
standard bicycle to maintain a similar stopping distance.
Rim brakes are still sufficient, and at least one comer-
cial electric bicycle has a rear strap brake: disc brakes are
not necessary in most cases. In fact, in regenerative sys-
tems, the motor will also contribute to braking—althoug h
this should not be relied upon since it depends upon cor-
rect motor, battery and controller operation, and can be
temporarily inactivated when th e battery is fully charged,
or controller temperature becomes elevated.
It is also important that motor power is de-asserted
during braking, and to this end most electric bicycles are
fitted with brake switches, which allow the controller to
detect brake application and turn the motor off accord-
Finally, the issue of theft should be mentioned. An
electric power assisted bicycle is likely to be more ex-
pensive than a standard bicycle, and thus a more attrac-
tive target of theft. It thus requires a good quality lock,
and deserves consideration of technological anti-theft
measures. Several authors have studied such systems, ge-
nerally by incorporating an electromagnetic deadlock
within the motor assembly. An alternative approach has
been taken by the Copenhagen Wheel project [28] which
determines the presence or absence of the owner when-
ever the vehicle moves and reacts appropriately.
5. Reflections from Singapore
The Singapore electric bicycle initiative (“ebi”) is a re-
search-intensive drive to determine the optimum pa-
rameters of a street-legal electric bicycle for the NTU
campus, and similar locations. Almost one hundred de-
sign combinations of features from Table 3 have been
tested across this campus by student volunteers for more
than a year (and some designs for over two years). A
Copyright © 2012 SciRes. JTTs
large amount of survey feedback information has been
analysed to form a set of reflections relating to electric
bicycles on (this) campus.
5.1. Environmental Factors
Apart from the issues mentioned previously that are ge-
neric to many campus environments worldwide, the NTU
campus is relatively hilly, suffers from widely separated
facilities and exists in a tropical climate where daytime
temperature lies between 28˚C and 30˚C year round and
rainfall is characterized by sudden torrential downpours
which result in significant water run- off into sto rm drains,
but which dry up within a few tens of minutes. In this
environment, it is unpleasant to be cycling in the rain.
The ambient temperature and high levels of humidity in
Singapore mean that almost any physical exertion more
strenuous than a stroll will result in severe perspiration
for most people [29]. Riding downhill feels pleasant due
to the cooling airflow, and slow flat riding is tolerable
most of the time, but uphill riding soon leads to perspiration.
In the tropical context, the authors hav e found that this
has become a barrier to the use of bicycles. One of the
most important features of the electric bicycle is its abil-
ity to assist the rider in hill-climbing. Indeed, on a
small-wheeled bicycle with sufficient pedal gearing, it is
quite possible to surmount relatively steep 10% hills
without undue p erspiration. In fact, the use o f an electric
motor to assist riders on the flat, and to provide most of
the motive effort uphill, on the ebi, provides an excellent
solution. The motor assistance allows riders to comforta-
bly cover distances and terrains that would otherwise
result in severe perspiration, and has proven to be a ma-
jor positive factor in the public acceptance of this solu-
tion for the campus.
NTU has many kilometres of covered walkways, built
to protect pedestrians from the heavy rain. Although it
may not be entirely legal to use them, the walkways have
proven to be an excellent resource for cyclists during
rainstorms. In fact, the latest campus plan outlines a
dual-path covered walkway concept—one side is re-
served for pedestrians, while the other side is available
for the use of cyclists (electric or otherwise). Although it
is possible to fit a roof or rain shield to any bicycle, the
riding characteristics differ as a result, especially in the
presence of crosswinds. Covered walkways or cyclepaths
are probably the best method of encouraging riders and
overcoming some of the main barriers noted in Section
2.2 by protecting riders from rain or excessive sunlight.
5.2. Social Issues
Students, as a group, may tend to be more environmen-
tally conscious than the population as a whole. There is
thus mileage to be gained by promoting the environmen-
tally sustainable characteristic of an electric bicycle that
is charged by being plugged into a solar energy grid. In
this area, success breeds success, with one of the biggest
factors in popularity appearing to be linked to those who
see the electric bicycles in action.
However there has been some concern regarding the
style of electric bicycles in general. Small wheeled ma-
chines, while more useful for hill-climbing, appear to be
less attractive than machines with larger wheels. The
placement of controller and battery also impacts the look
and feel of the machines. Many of the cheap bicycles
manufactured in China are considered by the student
population to be particularly ugly. This has been a sur-
prisingly significant consideration for wide scale adop-
tion: it is thus extremely important to have a solu tion that
is attractive, easy to ride, and evokes positive feelings in
both riders and other campus users.
Tied in with the look and feel of the bicycle is the fact
that a public-use scheme must cater to both male and
female students. Obviously there are several differences
between the typical anatomy of these two groups, and
this is reflected in general bicycle solutions for both
groups: the presence of a crossbar and the saddle shape
are the two main differentiating factors. Saddle and han-
dlebar height are two other considerations that need to
vary quite widely between taller and shorter riders, but
these can be accommodated quite easy with adjustable
stem and seat post.
The male/female shaped bicycle issue has been found
to be important. Many male students would not feel hap-
py riding a girl’s bicycle, irrespective of how comfort-
able it is (and it is often not particularly comfortable).
5.3. Mechanical Issues
With experience of various electric bicycles and compo-
nents in different arrangements, some useful insight has
been developed pertaining to use in public hire schemes.
Table 4 notes the various mechanical points noted during
the trials.
The final issue is security-an electric bicycle is a big-
ger investment and more attractive target of theft. Al-
though Singapore is an extremely safe place, and no bi-
cycles or components were lost during the trials, users
had to be careful to keep the machines locked when un-
5.4. Computational Technology
There is an increasing trend for greater and greater com-
putational complexity in consumer and transportation
devices. For example, modern motor cars may contain 40
or more embedded processors, driven by numerous fac-
tors which include the efficiency in terms of power and
cost that can be gained from the use of the devices, im-
Copyright © 2012 SciRes. JTTs
Table 4. Mechanical issues identified during the trials.
Motor cogging is a problem,
especially with larger direct
drive BLDC motors, causing
a noisy drive that is jerky
at low speed.
The centre of gravity of
bicycles, especially with high
battery placement, can lead to
instability. Falls when
mounting/dismounting are
Front wheel drive motors
tend to cause over-steer
during acceleration.
Heavy bicycles with
high-mounted batteries, when
parked, are dangerous if
knocked over.
Hub motors should not be
used with alloy forks, due to
danger of fracture (although
200 W and below may be
The changed centre-of-gravity
usually prevents a
actory-fitted kickstand from
operating correctly.
Torque arms are mandated
for larger hub motors, where
torque can be sufficient to
rotate the fixed axle, undo
the wheel-nuts and break the
drive cable.
Some of the geared hub motor s
available on the market are
asymmetrical (rear motors
should be, to accommodate the
gear block, but front motors
are often the same). This leads
to difficulties with rim brakes.
Chain-drive systems
experience enhanced chain,
gear and derailleur wear.
provements in operational effectiveness, additional fea-
tures and so on. The advantages in having a perceived
high-technology solution for advanced vehicles should
also not be under-estimated as a selling point. Bicycles,
similarly to motor cars, have also been equipped with
computers for many years-cycling computers can track
speed, distance, cadence and other attributes of a users
For electric bicycles, the use of modern BLDC motors
necessitates relatively complex control algorithms, usu-
ally provided by a simple microcontroller. These bicycles
thus already incorporate a simple computer, which can
conceivably also be used to provide standard bicycle
computer functions, perhaps augmented by the BLDC
controller access to additional sensing information.
Moving upward in technology (and requiring substan-
tially more computing power), GPS-assisted mapping
and navigation systems are as useful for bicycles as they
are for cars, moderated mainly by the reduced range of
most cycle riders compared to cars (i.e. they are more
likely to confine their journeys to areas that they are al-
ready familiar with). Electric vehicles of all types can
benefit from energy-aware route guidance—for example
how best to navigate from point A to point B given the
amount of energy available, knowledge of battery char-
acteristics and the usage patterns of the current rider
(which can be tracked or possibly inferred as a journey
For the NTU electric bicycle scheme, Android touch-
screen computers have been provided for every machine.
A custom navigation solution for the university cam-
pus, which encodes campus points of interest, pedestrian
Figure 3. Screen shots of the Android eBike application show-
ing navigation endpoint (top) and current location with des-
tination search bar (bottom).
areas, high traffic areas and safety blackspots, has been
written, called the eBike app (see Figure 3). This is based
upon an OpenStreetMaps dataset and a community fork
of the AndNav2 application. The NTU eBike app is open
source, freely available for download and modification.
In addition to navigation capabilities, IEEE802.11 com-
munications and a campus server allow each bicycle to
periodically announce their locations, receive messages,
and access location-aware services. These include social
networking-based applications which enable riders to
know where their friends are currently riding, participate
in campus discovery tours, operate a distance-based charg-
ing scheme and so on.
Although the energy-saving features of the current
campus bicycle computers are not particularly significant,
the usability aspects are important. These can be classi-
fied into social or technical spheres. Apart from the so-
cial aspects already mentioned, the authors have continu-
ally attempted to improve the attractiveness of these bi-
cycles for campus users (who are predominantly the un-
dergraduate stud ent population), in many ways including
choice of frame, colour scheme, styling, accessories and
so on. The use of an Android-based touch-screen system,
one of the most desirable and advanced computing solu-
tions currently available, increases the desirability of the
bikes for many users. Technical benefits of the system
Copyright © 2012 SciRes. JTTs
revolve around the ab ility to track the usage and location
of bicycles at all times: knowledge of routes, likely arri-
val times, predicting battery discharge rates and so on.
One significant improvement that the ebi computers
provide is the ability to advise rid ers which charging sta-
tion to aim towards. In cases where charging stations can
become periodically full (for example the charging sta-
tions at popular canteens during the lunch hours), there
exists a usability issue when riders head over to the can-
teen only to find no parking/charging stations free. Other
public hire systems, such as the Barclays public cycle
scheme in London, provide a touchscreen controller at
each charging location that can advise users of the status
of other nearby charging stations, including the number
of bays free. In the NTU scheme, the ability for the bicy-
cle and central server to communicate, allows the rele-
vant information to be advised to the cycles as they are
heading towards a particular charging station if that
charging station is full (or even likely to be full-re-
member, the location and destination of other riders is
similarly predictable in many cases). The destination can
be inferred based upon day and time, user, or pro gr amm ed
destination: particularly on the basis that users are more
likely to program unf amiliar destinations into the nav iga-
tion stations than familiar ones. Riders travelling to a
familiar destination-where they do not require navigation
information-would probably have made the journey be-
fore and thus have a relatively more predictable endpoint.
For the small pilot scheme run so far with very limited
charging locations, and few bicycles being equipped with
the computers, this feature of the system was not exer-
cised, but is expected to be an important usability im-
provement in larger scale schemes.
Regardless of the operational benefits provided thro-
ugh the use of capable and connected bicycle computers,
these are attractive to students and have been seen to
encourage users to value the cycles more. Increased ado-
ption rates are the eventual aim, and sometimes look-
and-feel is a more important human motivator than the
actual technical features that are provided.
5.5. Changing Attitudes
Retrospective to the initial campus trials of the ebi sys-
tem, users and potential users (80 people in total) were
surveyed to determine changes in attitudes to cycling
caused by the proposed solution, minus the Android bi-
cycle computer. An initial free-form survey was used to
derive a set of likely questions, formulated with reference
to Table 1. Some respondents had not ridden the eBikes
personally, but all were made aware of the scheme. Ta-
ble 5 presents the riding experience evaluation among
those who had ridden the eBikes.
Clearly, the scheme is considered to be convenient by
most users, relatively comfortable despite the smaller
Table 5. eBike riders evaluation of the riding experience.
Very goodGood Poor Very poor
Comfort 44% 50% 6% 0%
Convenience 50% 43% 6% 0%
Power 47% 47% 0% 6%
Stability 47% 35% 18% 0%
bicycle frames used, and sufficiently powerful (apart
from two respondents (6%) who, from their associated
written comments, appear to be motorcycle riders).
For all participants, it was important to validate the in -
ternational studies of Section 2.2 in the tropical campus
environment. Thus a number of questions were posed to
determine the perceived barriers to bicycle use. Respon-
dents who do not cycle regularly were asked to indicate
their main reasons, with 134 “excuses” being given across
14 classes, as plotted using the black coloured histogram
bars in Figure 4. The same questions were then repeated
for the situation where a full scale ebi scheme is in use as
proposed in this paper, plotted in the grey coloured his-
togram bars. The results very much validate Section 2.2
with the four primary international reasons (lack of fa-
cilities, inclement weather, distance/time issues and de-
gree of effort/hill climbing) featuring strongly in the list.
For the hilly NTU campus, hills are cited as a significant
barrier, related also to the complaint o f beco ming sweaty.
Tropical rain and lack of facilities are also significant
barriers. The road danger is an unusual response given
that the campus roads have a maximum vehicular speed
limit of 40 km/h. Comments by respondents clarify that
the concern is mainly due to narrow roads and lack of
cycling-friendly or cyclist-aware drivers in Singapore.
Interestingly, the adoption of electric bicycles can be
seen to solve the hill-climbing and sweatiness issue for
the majority of respondents (a stated aim of the system),
but acts to exacerbate the feeling of danger, concern over
lack of facilities (apart from showers which would no
longer be necessary), and highlights one factor we cannot
control easily; tropical rain.
Within the subset of respondents who have used an ebi
regularly (20), the issue of hills and sweatiness is very
much seen as solved (75% and 87.5% respectively). The
problems of rain and lack of facilities such as cycling lanes
or parking spaces, are not affected by the solution. Only the
issue of perceived danger is increased by the use of ebis,
perhaps due to the greater power available and increased
mass/momentum leading to a raised risk of damage.
Since the questions above are primarily negative, we
also attempted to gauge the positive aspects of electric
bicycle use on campus through the questions shown in
Table 6.
Evidently, electric bicycle use is seen as more envi-
ronmentally friendly than the alternative modes of transport,
Copyright © 2012 SciRes. JTTs
Copyright © 2012 SciRes. JTTs
Table 6. Positive aspects of eBike use on campus.
Very true
true Partly
untrue Definitely
friendly 80% 16% 5% 0%
It is convenient 48% 52% 0% 0%
It is safe 9% 4 2% 44% 5%
It is fun 71% 27% 2% 0%
It is quicker than
walking (on
campus) 86% 14% 2% 0%
It is quicker than
driving on campus 33% 37% 33% 0%
It looks “cool” 29% 37% 27% 10%
It is a cheap form
of transport 58% 26% 16% 2%
It makes me
feel good 49% 39% 10% 2%
is relatively conv enient, fun, q uicker than walk ing, cheap
and feels good. However it is not perceived as being safe
(perhaps linked to the same issues that arose in Figure 4),
is not particularly “cool” (remember that the Android
computer was not used on these bicycles). Respondents
were split on whether eBike use is quicker than driving.
This may be because of the very low proportion of re-
spondents who own a car. Starting from the laboratory
where the main charging station is located, it is actually
quicker to select an eBike, wheel outside cycle to any
location on campus and park at the building entrance,
than it is to head to the car park, unlock, enter and start
the car, manoeuvre out of the parking space, pay the
parking fee on exit, negotiate the speed bumps, exit the
car park junction, drive to the destination, enter a car
park, find a parking space, exit and lock the car and then
walk to the destination office.
Finally, and most positiv ely, 63% of surveyed campus
users are “very interested” in joining the eBike scheme,
35% are “interested” and only 3% are “not interested”.
Among other things, this shows that the solution is ac-
ceptable to a wide cross-section of potential participants,
male and female alike. From Table 6 we also noted that
71% of all respondents considered the solution to be fun.
These figures bode very well for user adoption of the ebi
when it is expanded in scale to cover all campus loca-
tions and users.
6. Conclusions
Bicycle use is known to be healthy, efficient, environ-
mentally friendly and in some localities is even faster
than driving (either due to traffic conditions, or the dis-
tance of available parking spaces from origin and desti-
nation respectively). Unfortunately, bicycle adoption
rates are not high in many places, due to various barriers
and perceived barriers to more widespread use.
Figure 4. Respondents attitudes are su rveyed con cerning barriers to use for s tandard bicycles and th e propos ed eBike solution .
This paper first explored the barriers to bicycle adop-
tion, in particular for a tropical university campus envi-
ronment, and hence propose technological means to
overcome these barriers by defining and testing a range
of electric bicycle alternatives to converge on a suitable
solution. The electric bicycles in question use a pedelec
sensor to control 200 to 250 W electric motors in a
rider-assist configuration (chosen to be in compliance
with Singaporean or European laws). The rider must pe-
dal, causing the motor to contribute to the motion. The
main aim in this environment being to ensure that whe-
ther the rider is going up hill, down, or riding on the flat,
their rate of energy expenditure can be maintained low
enough to prevent excessive perspiration.
These electric bicycles, of many types, have been
evaluated in practice in a semi-public hire scheme on the
Nanyang Technological University campus in Singapore.
The results of the study, including insights into the
scheme and various findings are presented here in this
The scheme has many more aspiring riders than can be
accommodated. It is a popular and useful service, with
some models of electric bicycle being very well-used.
Riders consider the majority of the electric bicycles to be
both comfortable and fun to use, and extremely conven-
ient for campus travel. Students and th e public alike view
the scheme positively, and we have seen a reduction in
the number of miles driven by car within the campus for
the majority of users who are also dr ivers.
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