Nowadays, people tend to use bicycles less as a kind of transport all over the world. It seems clear that the urbanization processes afford more people to move to big cities, where the opportunity to use a bicycle as a transport decreases compared to the countryside. In these terms, bicycle infrastructure is needed to be built in cities and urban areas in order to create ample opportunities for people to ride bicycles across the city.
Indeed, a lack of the infrastructure for bicycles and the other two-wheel transport remains the significant obstacle for bikers. When people live in a countryside they can use the same roads to ride bicycles as car drivers, but in cities it becomes almost impossible and hazardous. In fact, nowadays, a lot of people leave villages and move to urban areas and megapolises, so that is why new residents change their type of transport from bicycles to cars or public transports. To demonstrate, when I lived in a village, I often used my bike to get to different destinations; however, since I moved to Nizhny Novgorod city, I tend to use cars and the subway system, as the bicycle infrastructure is not developed enough there.
Taking this evidence into consideration, it is essential to point out that most of the cities in the world should allocate funds on the development of the bicycle infrastructure, such as distinct bike roads and bicycle sharing stations, and impose traffic rules to prevent chaotic driving. There is Amsterdam as a bright example, as there are thousands of miles of bicycle pathways across the city and the developed bike sharing system. Over 80% of the local population use bicycles every day, and that is how most of the cities in the world can exist like.
All in all, the main reason for a decreasing popularity of bicycles as a sort of transport is a lack of the developed infrastructure in big cities, where an array of people tend to move. Hence, implementation of bicycle-oriented transportation policy can attract people to use bicycles rather than cars and other transport.