A. In the middle of the twentieth century, many European and Latin American cities redesigned their streets around the private car. Cycle lanes were removed, and bicycles came to be seen as a vehicle for children or for those who could not afford a car. By 1970, cycling accounted for less than five per cent of trips in most large cities.
B. The oil crises of the 1970s prompted a partial reversal. Copenhagen and Amsterdam began to reintroduce protected lanes, partly in response to protests about road deaths among children. These cities now report that more than a third of commuting trips are made by bicycle, although researchers disagree about how much of this is due to infrastructure and how much to culture.
C. Bogotá offers a different model. Since 1974 the city has closed more than 100 kilometres of main roads to cars every Sunday, an event known as the Ciclovía. Supporters claim that the scheme has improved public health, but long-term medical data are limited, and the city has never published official figures on its effect on obesity.
D. The most recent change has come from technology. Shared electric bicycles allow riders to travel longer distances without arriving exhausted, and they have attracted older users in particular. Critics, however, point out that poorly managed schemes leave bicycles blocking pavements, and several cities have introduced fines for operators as a result.