A bicycle-sharing system, public bicycle system, or bike-share scheme, is a service in which bicycles are made available for shared use to individuals on a very short term basis. Bike share schemes allow people to borrow a bike from point "A" and return it at point "B". Many bike-share systems offer subscriptions that make the first 30–45 minutes of use either free or very inexpensive, encouraging use as transportation. This allows each bike to serve several users per day. In most bike-share cities, casual riding over several hours or days is better served by bicycle rental than by bike-share. For many systems, smartphone mapping apps show nearby stations with available bikes and open docks.
Bike-share began in Europe in 1965 and a viable format emerged in the mid-2000s thanks to the introduction of information technology. As of June 2014, public bikesharing systems were available in 50 countries on five continents, including 712 cities, operating approximately 806,200 bicycles at 37,500 stations. As of May 2011, the Wuhan and Hangzhou Public Bicycle bike-share systems in China were the largest in the world, with around 90,000 and 60,000 bicycles respectively. The Vélib' in Paris bicycle stations, is the largest outside of China. The countries with the most systems are Spain (132), Italy (104), and China (79). As of July 2013, the systems with the higher market penetration are both operating in France, the Parisian Velib' with 1 bike per 97 inhabitants and Vélo'v in Lyon with one bike per 121 residents.
Bicycle-sharing systems can be divided into two general categories: "Community Bike programmes" organised mostly by local community groups or non-profit organisations; and "Smart Bike programmes" implemented by government agencies, sometimes in a public–private partnership. The central concept of these systems is to provide free or affordable access to bicycles for short-distance trips in an urban area as an alternative to motorised public transport or private vehicles, thereby reducing traffic congestion, noise, and air pollution. Bicycle-sharing systems have also been cited as a way to solve the "last mile" problem and connect users to public transit networks.
The reasons people use bike-share vary considerably. Some who would otherwise use their own bicycle have concerns about theft or vandalism, parking or storage, and maintenance requirements.However, with limits on the number of places where bicycles can be rented or returned, the service resembles public transit, and has therefore been criticised as less convenient than a privately owned bicycle used door-to-door. Government-run bicycle-sharing programmes can also prove costly to the public unless subsidised by commercial interests, typically in the form of advertising on stations or the bicycles themselves.