The derailleur era is really about the slow evolution of the bicycle drivetrain over a 70 to 80 year period beginning in 1908. Early development of derailleurs started with French efforts to improve on the gearing systems where riders—while pedaling—were using a finger, wire or a metal hook to derail the chain onto a bigger or smaller chainring.
Author Frank Berto, in his 2005 book The Dancing Chain points to the turn of the century as a transition point for bicycle development:
“…around 1908 there was a fork in the road: English cyclists took the right fork and would pedal their three-speed epicyclic hub gears for the next 40 years. French cyclists took the left fork and rode their derailleur gears right up to the present. American cyclists fell down a hole in the road and continued to pedal single-speed coaster-brake bicycles for the next 60 years.”
Berto’s humorous summation points to a stark difference in the acceptance of bicycles in England, France and the United States. The French developed a culture of bicycles built for speed and efficiency, perhaps through the popularity of racing and bicycle touring. The French bicycle culture accepted the emerging derailleur as the appropriate technology for a geared bicycle transmission. The English avoided the noisy and finicky derailleurs, preferring instead the direct chain alignment and low-maintenance of internal hub gears. In America, bicycles with no gearing system dominated the market, partly because the automobile served the daily transportation needs for adults, while the bicycle stagnated as a child’s product.