They are everywhere in Cuba and for good reason. Bicycles are cheap efficient transportation.
Cubans also modify bicycles in all kinds of ways. They stretch the frames, add seats, and make them tricycle pedicabs or make them into carts to carry goods for sale.
Bicycles, like autos, do break. Pedals, seats, chains and of course tires and tubes are needed, but parts are difficult to get. This creates a whole (capitalist) black market repair service. I watched a man vulcanize a tube in his small shop. I saw another mechanic on the street digging through a bucket of rusty parts looking for the correct sized bolt. He had a collection of mis-matched tools that I’m certain had been made years ago.
Of course, as a photographer, old bicycles make great subjects too.