What is this style called

Maybe it was the "science fiction" of long ago.

The fact that you mentioned zeppelins and flying bikes makes me think it might be steampunk that you are thinking of. (following definition from Wikipedia)

Steampunk is a sub-genre of fantasy and speculative fiction that came into prominence in the 1980s and early 1990s. The term denotes works set in an era or world where steam power is still widely used—usually the 19th century, and often Victorian era England—but with prominent elements of either science fiction or fantasy, such as fictional technological inventions like those found in the works of H. G. Wells and Jules Verne, or real technological developments like the computer occurring at an earlier date. Other examples of steampunk contain alternate history-style presentations of "the path not taken" of such technology as dirigibles, analog computers, or digital mechanical computers (such as Charles Babbage's Analytical Engine); these frequently are presented in an idealized light, or with a presumption of functionality.

Ya learn something new everyday around here ...

oooooh the humanity