Boom era (modern) refers the to the US sales spike of 1971-1974 inclusive. Bicycle sales increased slowly but steadily after Word War II increasing by about 5 million units total over 15 years. Then sales jumped from 7 million in 1970 to 9 million in 1971 (28% increase). 1972 saw sales rise further to 12 million (25% increase) with a peak of 15 million in 1973 (25% increase). 1974 fell slightly to 14 million, then halved in 1975 to the pre-boom total of 7 million. Despite a steadily growing population, the 15 million peak was not passed again until 1992, with the popularity of the mountain bike.

There was also a late 19th century boom during the initial popularity of the bicycle.