An electric bicycle, also known as an e-bike, is a bicycle with an electric motor used to power the vehicle. Electric bicycles typically cost between US$500 and US$3,000, use rechargeable batteries and can travel up to 15 to 20 miles per hour (24 to 32 km/h). Depending on the laws of the country in which they are sold, in some markets they are rapidly replacing traditional bikes and motorcycles.[1][2]
In many parts of the world, electric bicycles are classified as bicycles rather than motor vehicles, so they are not subject to the more stringent laws regarding certification and operation of motor vehicles. Electric bicycles are one type of motorized bicycle. However, electric bicycles are defined separately and treated as a specific vehicle type in many areas of legal jurisdiction.
Electric bicycle usage worldwide has experienced rapid growth since 1998. It is estimated that there were roughly 120 million e-bikes in China as of early 2010, and sales are expanding rapidly in India,the United States of America, the Netherlands [1] and Switzerland.[3] A total of 700,000 electric bicycles were sold in Europe in 2010, up from 200,000 in 2007 and 500,000 units in 2009.[4]
Contents |
In the 1890s, electric bicycles were documented within various U.S. patents. For example, on 31 December 1895 Ogden Bolton Jr. was granted U.S. Patent 552,271 for a battery-powered bicycle with “6-pole brush-and-commutator direct current (DC) hub motor mounted in the rear wheel.” There were no gears and the motor could draw up to 100 amperes (A) from a 10-V battery.[5]
Two years later, in 1897, Hosea W. Libbey of Boston invented an electric bicycle (U.S. Patent 596,272) that was propelled by a “double electric motor.” The motor was designed within the hub of the crankshaft axle.[6] This model was later re-invented and imitated in the late 1990s by Giant Lafree electric bicycles.
By 1898 a rear wheel drive electric bicycle, which used a driving belt along the outside edge of the wheel was patented by Mathew J. Steffens. Also, the 1899 U.S. Patent 627,066 by John Schnepf depicted a rear wheel friction “roller-wheel” style drive electric bicycle.[7] Schnepf's invention was later re-examined and expanded in 1969 by G.A. Wood Jr. with his U.S. Patent 3,431,994. Wood’s device used 4 fractional horsepower motors; each rated less than ½ horsepower and connected through a series of gears.[8]
Torque sensors and power controls were developed in the late 1990s. For example, Takada Yutky of Japan filed a patent in 1997 for such a device. In 1992 Vector Services Limited offered and sold an electric bicycle dubbed Zike.[9] The bicycle included Nickel-cadmium batteries that were built into a frame member and included an 850 g permanent-magnet motor. Despite the Zike, in 1992 hardly any commercial electric bicycles were available.
In 1997 Raleigh released the Select, a successful commercially available electric bike. At the beginning of the 21st century two big electrical manufacturers produced a sealed drive unit, that drove through the crank. First Yamaha, then quickly followed by Panasonic. Panasonic was fitted to the Giant Lafree between 2000-2006. When production ceased of this model Several other manufacturers started to use this system. Today, Raleigh,Swiss Flyer, Monarch, Kettler and Kalkhoff are amongst the top manufacturers featuring this system on their bikes.
By 1998 there were at least 49 different electric bicycle models available. Production grew from 1993 to 2004 by an estimated 35%. By contrast, according to Gardner, in 1995 regular bicycle production decreased from its peak 107 million units.
Some of the less expensive electric bicycles used bulky lead acid batteries, whereas newer models generally used NiMH, NiCd and/or Li-ion batteries which offered lighter, denser capacity batteries. The end benefits usually varied from manufacturer; however, in general there was an increase in range and speed.
By 2001 the terms E-Bike, power bike, pedelec, assisted bicycle and power-assisted bicycle where commonly used to describe electric bicycles. E-bike, according to Google, is a term that has increased in popularity. This term generally referred to an electric bicycle which used a throttle. The terms Electric Motorbike or E-Motorbike have been used to describe more powerful models which attain up to 80 km/h. By 2004 electric bicycles where manufactured by eZee, Yamaha, Honda, Panasonic, Currie Technologies, EV Global, Optibike, Giante Lite, Mérida, ZAP.
In a parallel hybrid motorized bicycle, such as the aforementioned 1897 invention by Hosea W. Libbey, human and motor inputs are mechanically coupled either in the bottom bracket, the rear or the front wheel, whereas in a (mechanical) series hybrid cycle, the human and motor inputs are coupled through differential gearing. In an (electronic) series hybrid cycle, human power is converted into electricity and is fed directly into the motor and mostly additional electricity is supplied from a battery.
The term "pedelec" generally refers to an electric bicycle that incorporates a torque and/or speed sensor with a power controller that delivers assist only when the rider pedals. On the opposite side, a Noped is a term used by the Ministry of Transportation of Ontario for similar type vehicles which do not have pedals or in which the pedals have been removed from their motorized bicycle. Finally, Assist Bicycle is the technical term used to describe such a vehicle and Power-Assisted Bicycle is used in the Canadian Federal Legislation, but is carefully defined to only apply to electric motor assist, and specifically excludes internal combustion engines (though this is not the case in the United States).
Today, China is the world's leading producer of electric bicycles. According to the data of the China Bicycle Association, a government-chartered industry group, in 2004 China's manufacturers sold 7.5 million electric bicycles nationwide, which was almost twice the year 2003 sales;[10] domestic sales reached 10 million in 2005, and 16 to 18 million in 2006.[11] By 2007, electric bicycles were thought to make up 10 to 20 percent of all two-wheeled vehicles on the streets of many major cities.[11] A typical unit requires 8 hours to charge the battery, which provides the range of 25–30 miles (40–50 km),[11] at the speed of around 20 km/h.[10]
A large number of such vehicles is exported from China as well (3 million units, worth 40 billion yuan ($5.8 billion), in the year 2006 alone),[12]
An electric bicycle which requires the rider to pedal in order to activate the motor is known as a pedelec.[13]
In Australia the legal motor power limit in all states is 200W (October 2010) though various groups are lobbying for an increase in this low limit to encourage their use. There is no speed limit and no need for a pedal sensor. Some states have their own rules such as no riding under electric power on bike paths and through built up areas so riders should view the state laws regarding their use. There is no licence and no registration required for electric bicycle usage. The law is not heavily policed due to difficulty determining if the electric power is in operation at the time and ambiguity about the methods of testing motor output. It is currently still legal to pedal a 1000W electric bicycle if not employing power. Many people often purchase higher powered electric conversion kits and convert their own regular bicycle into an electric bicycle as this is the only option available for people with low pedalling abilities or very hilly residences if they wish to use an electric bike. The main electric bicycles in Australia come from a variety of importers getting rather generic 200W electric bikes from China with both lead acid and lithium ion battery options, these generally retail for between $1300 – $1800 (AUD). There are some upmarket models available for around the $4000 mark. The legal requirements for selling is to have the components tested by an engineer and to ensure the battery charger has Australian electrical approval. There is one group in Australia solar charging these electric bicycles (called Solar Bike [14] ) and for that there is no legal requirement.
Eight provinces of Canada allow electric power assisted bicycles. A three-year trial in Ontario ended October 2009. In seven of the eight provinces, e-bikes are limited to 500W output, and cannot travel faster than 32 km/h (20 mph) on motor power alone on level ground. In Alberta the limits are 750W and 35 km/h.[15] Age restrictions vary in Canada. All require an approved helmet. Regulations may or may not require an interlock to prevent use of power when the rider is not pedaling. Some versions (e.g., if capable of operating without pedaling) of e-bikes require drivers' licenses in some provinces and have age restrictions. Vehicle licenses and liability insurance are not required. Generally they are considered vehicles (like motorcycles and pedal cycles), so are subject to the same rules of the road as regular bicycles. In some cases regulatory requirements have been complicated by lobbying in respect of the Segway HT.
Bicycles assisted by a gasoline motor or other fuel are regulated differently than ebikes. These are classified as motor cycles regardless of the power output of the motor and maximum attainable speed.
In China electric bikes currently come under the same classification as bicycles and hence don't require a driver's license to operate. Previously it was required that users registered their bike in order to be recovered if stolen, although this has recently been abolished. Due to a recent rise in electric-bicycle-related accidents, caused mostly by inexperienced riders who ride on the wrong side of the road, run red lights, don't use headlights at night etc., the Chinese government plans to change the legal status of illegal bicycles so that vehicles with an unladen weight of 20 kg or more and a top speed of 30kmh or more will require a motorcycle license to operate, while vehicles lighter than 20 kg and slower than 30kmh can be ridden unlicensed. In the southern Chinese cities of Guangzhou, Dongguan and Shenzhen, electric bicycles, like all motorcycles, are banned from certain downtown districts. There are also bans in place in small areas of Shanghai, Hangzhou and Beijing. Bans of scooter style electric bikes (SSEB) were however cancelled and in Shenzhen electric bicycles may be seen on the streets nowadays (2010–11).
European Union directive 2002/24/EC exempts vehicles with the following definition from type approval: "Cycles with pedal assistance which are equipped with an auxiliary electric motor having a maximum continuous rated power of 0.25 kW, of which the output is progressively reduced and finally cut off as the vehicle reaches a speed of 25 km/h or if the cyclist stops pedaling.” This is the de facto definition of an electrically assisted pedal cycle in the EU. As with all EU directives, individual member countries of the EU are left to implement the requirements in national legislation.
European product safety standard EN 15194 was published in 2009. The aim of EN 15194 is "to provide a standard for the assessment of electrically powered cycles of a type which are excluded from type approval by Directive 2002/24/EC".[16]
In New Zealand an electric bicycle is considered to be a 'Power-assisted cycle'. A power-assisted cycle is a cycle that has a motor of up to 300 watts. The law treats these as ordinary cycles rather than motorcycles. This means that it is not necessary to register or license them.[17]
In the United Kingdom electric bicycles are classed as standard bicycles providing the motor's power output does not exceed 250W[18] and cuts out once the bike reaches 15.5 mph. It must also be under 40 kg. This means the rider does not require a license to use them, however riders must be of at least 14 years of age. There is a small but growing market in the UK[19] consisting of brands such as Kalkhoff, Sparta, Koga, Spencer Ivy, Cytronex, Wisper, eZee, PowaCycle and PowaByke.
Federal law in the United States states that an electric bicycle must have a top speed when powered solely by the motor under 20 mph and a motor which produces less than 750 watts/1 hp. They are not considered motor vehicles by the federal government and are subject to the same consumer safety laws as unassisted bicycles.[20] Their legality on public roads is under state jurisdiction, and varies. See the main Electric bicycle laws article for details on the law in individual states.
In addition to federal electric bicycle laws, the state of Illinois added that the operator be at least 16 years of age. A license and registration is not required.[21]
New York State law bans motor-assisted bicycles from state roads and city streets, though the ban is not currently enforced and a bill is under consideration to allow electric bikes with a top speed of 20 mph and less than 1,000 watts of power.[1][22]
There are many possible types of electric motorized bicycles with several technologies available, varying in cost and complexity; direct-drive and geared motor units are both used. An electric power-assist system may be added to almost any pedal cycle using chain drive, belt drive, hub motors or friction drive. BLDC hub motors are a common modern design with the motor built into the wheel hub itself and the stator fixed solidly to the axle and the magnets attached to and rotating with the wheel. The bicycle wheel hub is the motor. The power levels of motors used are influenced by available legal categories and are often limited to under 750 watts.
Electric bicycles use rechargeable batteries, electric motors and some form of control. Electric bicycles developed in Switzerland in the late 1980s for the Tour de Sol solar vehicle race came with solar charging stations but these were later fixed on roofs and connected so as to feed into the electric mains.[23] The bicycles were then charged from the mains, as is common today. Battery systems in use include lead-acid, NiCd, NiMH and Li-ion batteries.
Range is a key consideration with electric bikes, and is affected by factors such as motor efficiency, battery capacity, efficiency of the driving electronics, aerodynamics, hills and weight of the bike and rider. The range of an electric bike is usually stated as somewhere between 7 km (uphill on electric power only) to 70 km (minimum assistance) and is highly dependent on whether or not the bike is tested on flat roads or hills.[24] Some manufacturers, such as the Canadian BionX or American E+ (manufactured by Electric Motion Systems), have the option of using regenerative braking, the motor acts as a generator to slow the bike down prior to the brake pads engaging.[25] This is useful for extending the range and the life of brake pads and wheel rims. There are also experiments using fuel cells. e.g. the PHB. Some experiments have also been undertaken with super capacitors to supplement or replace batteries for cars and some SUVS.
The energy costs of operating electric bicycles are small, but there can be considerable battery replacement costs. Riding an electric bicycle to work or to the store instead of taking a car has long term financial and health gains.
Control can be as simple as an on-off switch but more usually they are power-on-demand, where the motor is activated by a handlebar mounted throttle, and/or a pedelec (from pedal electric), also known as electric assist, where the electric motor is regulated by pedaling. These have a sensor to detect the pedaling speed, the pedaling force, or both. Brake activation is sometimes sensed to disable the motor as well.
There are two distinct types of electric bike controllers designed to match either a brush or brushless motor. Brushless motors are becoming more common as the cost of controllers continues to decrease. The page on DC motor covers the differences between the two types.
Electric bicycles require high initial torque and therefore models that use brushless motors typically have Hall sensor commutation for speed measurement. An electronic controller provides assistance as a function of the sensor inputs, the vehicle speed and the required force. The controllers generally provide potentiometer-adjustable motor speed, closed-loop speed control for precise speed regulation, protection logic for over-voltage, over-current and thermal protection. The controller uses pulse width modulation to regulate the power to the motor. Sometimes support is provided for regenerative braking but infrequent braking and the low mass of bicycles limits recovered energy. An implementation is described in an application note for a 200 W, 24 V Brushless DC (BLDC) motor.[26]
Brush motors are also used in electric bikes but are becoming less common due to their intrinsic lower efficiency. Controllers for brush motors however are much simpler and cheaper due to the fact they don't require hall sensor feedback and are typically designed to be open-loop controllers.
Not all electric bicycles take the form of conventional push-bikes with an incorporated motor, such as the Cytronex bicycles which use a small battery disguised as a water bottle.[27] .[28] Some are designed to take the appearance of low capacity motorcycles, but smaller in size and consisting of an electric motor rather than a petrol engine. Bicycles of note include the Sakura electric bicycle, which incorporates a 200W motor found on standard e-bikes, but also includes plastic cladding, front and rear lights, and a speedometer. It is styled as a modern moped, and is often mistaken for one based on its similarity in appearance.
An Electric Pusher Trailer is another take on electric bike design which incorporates a motor and battery into a trailer that pushes any bicycle. One such trailer is the two-wheeled Ridekick. [29]
Other, rarer designs include that of a 'chopper' styled electric bicycle, which are designed as more of a 'fun' or 'novelty' electric bicycle than as a purposeful mobility aid or mode of transport.
Electric cargo bikes [30] allow the rider to carry large, heavy items which would be difficult to transport without electric power supplementing the human power input.
Various designs (including those mentioned above) are designed to fit inside most area laws, and the ones that contain pedals can be used on roads in the United Kingdom, among other countries.
Most electric bicycles can be locked using keys supplied by the manufacturer. The key is usually inserted into a switch, which is commonly found on the bicycle's handlebars or on one side of the motor compartment. When switched to the "Off" position, the electrical drive system cannot be turned on. In areas of high risk for bicycle theft, these locking mechanisms are used in conjunction with coil or U locks.
Electric bikes can be a useful part of cardiac rehabilitation programmes, since health professionals will often recommend a stationary bike be used in the early stages of these. Exercise-based cardiac rehabilitation programmes can reduce deaths in people with coronary heart disease by around 27%;[31] and a patient may feel safer progressing from stationary bikes to electric bikes.[32] They require less cardiac exertion for those who have experienced heart problems.[33]
Most electric bicycles can be classified as zero-emissions vehicles, as they emit no combustion byproducts. The environmental effects of electricity generation and power distribution and of manufacturing and disposing of (limited life) high storage density batteries must be taken into account. Even with these issues considered, electric bicycles will have significantly lower environmental impact than conventional automobiles, and are generally seen as environmentally desirable in an urban environment. The small size of the battery pack on an electric bicycle, relative to the larger pack used in an electric car, makes ebikes very good candidates for charging via solar power or other renewable energy resources. Sanyo capitalized on this benefit when it set up "solar parking lots," in which ebike riders can charge their vehicles while parked under photovoltaic panels.[34]
The environmental credentials of electric bikes, and electric / human powered hybrids generally, have led some municipal authorities to use them, such as Little Rock, Arkansas with their Wavecrest electric power-assisted bicycles or Cloverdale, California police with Zap electric bicycles. China’s e-bike manufacturers, such as Xinri, are now partnering with universities in a bid to improve their technology in line with international environmental standards, backed by the Chinese government who is keen to improve the export potential of the Chinese manufactured e-bikes.[35]
A recent study on the environment impact of electric bicycles vs other forms of transportation[36] found that electric bikes are about:
China's experience, as the leading e-bike world market, has raised concerns about road traffic safety and several cities have considered banning them from bicycle lanes.[1] As the number of e-bikes increased and more powerful motors are used, capable of reaching up to 30 miles per hour (48 km/h), the number of traffic accidents have risen significantly in China. E-bike riders are more likely than a car driver to be killed or injured in a collision, and because e-bikers use conventional bicycle lanes they mix with slower-moving bicycles and pedestrians, increasing the risk of traffic accidents.[1]
China has experienced an explosive growth of sales of electric bicycles and scooters, with annual sales jumping from 56 thousand units in 1998 to over 21 million in 2008,[37] and reaching an estimated fleet of 120 million e-bikes as of early 2010.[1][38] This boom was triggered by Chinese local governments' efforts to restrict motorcycles in city centers to avoid traffic disruption and accidents. By late 2009 motorcycles are banned or restricted in over ninety major Chinese cities.[37] Users began replacing traditional bicycles and motorcycles and, in e-bike became an alternative to commuting by car.[1] Nevertheless, road safety concerns continue as around 2,500 electric bicycle related deaths were registered in 2007.[38] As of late 2009 ten cities have also banned or imposed restrictions on electric bicycles on the same grounds as motorcycles. Among these cities are Guangzhou, Shenzhen, Changsha, Foshan, Changzhou, and Dongguang.[37][38]
China is the world's leading manufacturer of electric bicycles, with 22.2 million units produced in 2009. Production is concentrated in five regions, Tianjin, Zhejiang, Jiangsu, Shandong, and Shanghai.[39] China exported 370,000 e-bikes in 2009.[40]
Sales of e-bikes in Germany increased almost three times between 2007 and 2010, from 70,000 to 200,000 units per year.[4]
The Netherlands is considered the bicycle capital of the world, with a fleet of 18 million bicycles that account for 40% of all traffic movements.[41] Electric bicycles have reached a market share of 10% by 2009, as e-bikes sales quadrupled from 40,000 units to 153,000 between 2006 and 2009,[42] and the electric-powered models represented 25% of the total bicycle sales revenue in that year.[41] By early 2010 one in every eight bicycles sold in the country is electric-powered despite the fact that on average an e-bike is three times more expensive than a regular bicycle.[38][42]
A 2008 market survey showed that the average distance traveled in the Netherlands by commuters on a standard bicycle is 6.3 kilometres (3.9 mi) while with an electric bike this distance increases to 9.8 kilometres (6.1 mi).[43] This survey also showed that e-bike ownership is particularly popular among people aged 65 and over, but limited among commuters. The electric bicycle is used in particular for recreational bicycle trips, shopping and errands.[43]
Since 2002, federal legislation classifies any two-wheel pedal-driven vehicle with a maximum speed of 20 miles per hour (32 km/h) as a bicycle, removing doubts about the legal status of e-bikes.[44] Nevertheless, there are restrictions in place at the state level, and most states limit power output to 750 watts.
As of 2009 the U.S. had an estimated fleet of 200,000 electric bicycles.[40]
PikeResearch, a for-profit market research firm, released a report in 2010 which included market analysis and forecasts for electric two-wheel vehicles. They conclude that, "The worldwide electric two-wheel vehicle market is expected to grow at a compound annual rate of 9% through 2016" and that "a lack of a well-defined retail channel hampers faster adoption in North America and Europe."[45] PikeResearch also forecasted that worldwide sales of e-bikes, e-motorcycles, and e-scooters will reach more than 466 million between 2010 to 2016, and China will continue to dominate the world market, with more than 95% of sales during this period. E-bikes sales are expected to have the largest share with 56% of the market.[46]
However, the Los Angeles Times reported that electric bicycle sales in the U.S. have slowed in 2010 compared to 2009. This could be due to a slowing economy and lower gas prices."[47]
|
||||||||||||||||||||||||||