|Fig. 1: Diagram of a standard electric bike with three main components: hub motor, controller and battery. (Source: Wikimedia Commons|
In the late 90s, annual electric bike sales in China experienced a huge spike in sales, reflecting a rapid shift from gasoline-powered scooters and human-powered bicycles to all-electric vehicles. Indeed, electric bike sales went from 150,000 in 1999 to 21 million in 2007, a growth in sales that is unmatched by any other mode of transportation in China.  However, some local governments in China are outright banning e-bikes from circulation. In this article, we will highlight the important technical, political and economic factors that allowed e-bikes to explode onto the Chinese scene, in the hope of informing increased mobility needs in developing countries. We will also explore the challenges the industry faces as it seeks to further grow.
Electric bikes in China can be categorized as bicycle-style electric bikes (BSEB) or scooter-style electric bikes (SSEB). These two types act as two ends of a spectrum. On the BSEB side, e-bikes will resemble the typical bicycle with functional pedals; on the SSEB side, e-bikes more closely resemble scooters with turn signals and brake lights. Despite these aesthetic differences, the underlying technology is similar. Most e-bikes can be broken down into three component parts: a hub motor, controller and battery. While BSEBs have smaller 36V batteries and lower-powered 180-250W motors, SSEB's have 48V batteries and 350-500W motors. Although e-bikes are regulated to not exceed 20 km/h, many users claim that SSEBs can do top speeds of almost 40 km/h, with a range of about 25-50km on one charge.  Approximately 95% of e-bikes in China are powered by lead acid batteries, where the lead content of the electric battery is 70% of its weight. The lifespan of such a battery is around 10,000 km or typically 1 to 2 years of bicycle use. 
In 1991, the Chinese government made developing e-bikes an official technology goal.  In subsequent years, local governments started to enforce motorcycle bans by suspending the issuance of new motorcycle licenses, access to downtown regions and major roads, and capping the number of available licenses. These policies were motivated by a desire for traffic congestion relief, improved safety and a reduction in pollution. E-bikes, however, escaped regulations - being categorized as non-motor vehicles - and thus filled the vacuum left by motorcycles. Local governments then pushed further for the adoption of e-bikes: cities were redeveloped with extensive bicycle lanes and licensing fees on gas-powered scooters were raised.  From an economic standpoint, the rapid adoption of e-bikes in China can be attributed to several factors, including rising income levels and decreasing costs of e-bike technology. Between 1997 and 2004, the average disposable income in China increased 82% from $645/year to $1180/year. With the average e-bike costing $188 in 2003, the average Chinese consumer could spend more and more on transportation needs. This effect was accentuated by rising fuel prices and falling electricity prices in rural areas. 
From a technological standpoint, improvements in e-bike technology also pushed e-bike growth further. The two components that made major technological improvements were the battery and motor. Between 1997 and 2006, the energy density of e-bike batteries increased 33% from 30Wh/kg to 40 Wh/kg and battery life also increased 35% to over 300 cycles.  These improvements can be attributed to advances in lead-acid batteries; manufacturers began to use fixed electrolyte instead of the liquid acid electrolyte used previously. Where liquid electrolyte required care in use, fixed electrolyte does not risk leaks or property damage if a bike falls over. E-bike motors also experienced advances. In the early 2000s, manufacturers started to make more sophisticated brushless motors. Although this type of motor is more expensive and heavier, its lower rounds per minute (300 rpm for brushless versus 2,000 rpm for brush) meant lower maintenance and higher efficiency. 
Despite incredible growth, e-bikes have introduced new concerns. In November 2006, under advice from the traffic management bureau, Guangzhou became the third city in China to ban e-bikes. There are multiple motivations behind this ban. Firstly, during operation, e-bikes are so quiet that they are imperceptible to both pedestrians and drivers, which makes the e-bike prone to accidents.  Secondly, an accident analysis revealed that over 60% of fatal crashes involving two-wheelers resulted from violation of traffic rules, citing red-light running as a major reason for accidents.  Thirdly, e-bikes are not the most efficient use of available road space, as although they move more people per lane than cars, public transportation like buses can move more people. 
Finally, although e-bikes by definition do not emit tail-pipe emissions, they contribute indirectly to pollution through both lead loss and power plant emissions, resulting in serious health implications.  In China, poor production and recycling processes caused by small-scale, dispersed and outdated industry, translates to high lead loss. Given a contested 90% rate of lead recycling in China, e-bikes emit in excess of 400mg/km of lead.  This is compounded by the fact that e-bikes, unlike other vehicles, require battery replacement every 1 to 2 years. Moreover, a standard electric bike requires 2.1 kWh/100km, and thus, depending on fuels used for power generation, e-bikes will indirectly emit greenhouse gases and conventional pollutants. On average, an e-bike will emit around 21 g/km of CO2, which is considerably lower than any other comparable mode of transportation but remains an obstacle for increasingly polluted cities. [1,2]
The incredible growth of e-bike sales in China in the late 90s can be attributed to a combination of technical, political and economic factors. For example, e-bike technology improved drastically, government policy disincentivized motorcycle use and the average Chinese person's disposable income almost doubled. However, following the e-bikes rise in popularity came governmental concerns over safety, pollution and efficiency.
In order to meet these concerns, China must continue to develop regulations that will minimize the safety issues related to e-bike use. Many of the negative environmental effects of e-bikes can also be reduced through technological advances. For example, encouraging a transition to advanced batteries (i.e. Li-ion, Ni-MH) for e-bikes would greatly reduce waste from lead batteries. Although the current market for such batteries is small, the market will grow in the future by virtue of rising lead prices and falling Li-ion battery prices. 
© Quentin Perrot. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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