London is a metropolis plagued by hellish traffic; gridlock and bottlenecks that can cause total standstill are frequent throughout the city center, and even within its vast suburbs. London was the largest city in the world during the 19th century, and even today its metropolitan area has about ten million inhabitants, putting it among the four most populated metropolitan areas in Europe (the other three being Paris, Moscow and Istanbul).
Bicycle use in London has increased, but only in recent years, and especially since Boris Johnson became mayor, an unconventional Tory [Conservative] in that he uses his bike to travel within the city.
Many bike lanes have been created alongside the primary streets, as well as bike routes within the large parks, and under construction is a “Cycle Superhighway" along the Thames, which should become the backbone of the London biking network.
The bike lanes are often separated from traffic only by a white stripe and indicated by a bicycle icon. In some cases the lane is colored in blue or green, or even in other colors. Physically-separated dedicated bike lanes are rare and therefore there are often situations of cars encroaching on the bike lane; in other words, the cyclist must always be on one's guard.
The danger for cyclists from London traffic has become a contentious subject in recent years, especially in light of the not-inconsiderable number of documented deaths. In fact, the Salvaiciclisti [save the cyclists] movement had its roots in London.
Bike racks are somewhat rare.
As mentioned at the beginning, the number of Londoners who ride bikes has been growing steadily, doubling in the first decade of the 21st century, but still far from the more bicycle-culture cities of Central Europe.
Throughout London there are numerous self-service bike docking stations, managed by Banco Santander; in fact, many of the cyclists seen around London, especially in the parks, use the distinctive red Santander bikes.