With car sales in China routinely topping two million a month, traffic and pollution are major concerns. In a bid to cut traffic and promote the environment and health, many Chinese cities are now encouraging bike sharing companies.

Rental users continue to increase and are expected to reach at least 10 million by 2019 according to the 2016 China bike-sharing service report.

Mobike and ofo are the two largest bike-sharing services in China. Mobike founded in 2015, is popular in most major cities, while ofo is big on college campuses.

Companies use the honor system to make sure as many people as possible can use the bikes. But some problems include disorderly parking, theft, and damaged. The 2016 China’s bike-sharing market research report showed 53.5 percent of people thought disorderly parking was the top issue.

ofo has hired workers to ensure the bikes are returned in good condition and parked properly. Mobike has enlisted its users to help track down lost bikes and maintain orderly parking. Some local governments have rolled out rules to regulate parking.

Minister Li Xiaopeng said it requires joint efforts from the government, service providers and customers to maintain smooth rides for shared bikes.