America’s collective wealth more than doubled in a decade when change was the only constant. Mass communication and cheap transportation let us listen to the same music, buy the same goods and adopt a relatively common culture. Babe Ruth hit 60 home runs yet Mickey Mouse became the most well-known Yankee in the world. On the flipside, Jazz Age hypocrisy outlawed booze with the 18th Amendment and supported the rise of organized crime and, eventually, stock-car racing. As the decade ended, Adolf Hitler and Benito Mussolini cast a menacing shadow over Europe as America inched toward crushing financial disaster.
American women gain full voting rights.
Eugene Walker sets a new FIM top-speed record of 109 mph on an Indian. The racer is credited with popularizing the technique of putting a foot down through turns, previously considered cowardly.
Harley-Davidson becomes the largest motorcycle manufacturer in the world, with dealers in 67 countries. In 1920, The Motor Company produces 28,189 machines.
Shortly after selling Henderson to Ignaz Schwinn in 1917, Bill Henderson founded ACE in Philadelphia. The 1920 ACE is a beautiful air-cooled inline-four displacing 1168-1266cc, depending on the model.
Harley-Davidson's Otto Walker becomes the first rider to average over 100 mph during a race at the 1-mile board track in Fresno, California.
Moto Guzzi begins selling its first production motorcycle, the Normale. The firm’s original 500cc horizontal-single uses an intake-over-exhaust design that endures for the next 50 years.
The Triumph Ricardo is introduced at the Isle of Man. Designed by Sir Harry Ricardo, with a four-valve head and central sparkplug, the 499cc single produces outstanding power for its size.
The first 1200cc (74 cubic inch) Harley-Davidson V-twin is introduced.
The USSR, a.k.a. the Soviet Union, is established.
Egypt becomes an independent nation. It had been part of the British Empire since 1882.
Air cleaners are introduced on production motorcycles for the first time.
Hap Jones buys his first motorcycle. He goes on to win many races and establish a long-running motorcycle accessories distribution company.
Banned from producing aircraft following WWI, BMW begins building motorcycles. The first example is the 1923 R32, which utilizes an opposed-twin engine and shaft drive—two features that would become synonymous with the brand.
IBM is founded in Armonk, New York, offering tabulating solutions for large businesses.
President Calvin Coolidge delivers the first presidential radio address from the White House.
The Motorcycle & Allied Trades Association, successor to the Federation of American Motorcyclists, re-registers as the American Motorcycle Association. The occasion is enthusiastically reported in the May 20, 1925, issue of Western Motorcyclist and Bicyclist. Annual membership costs just $1.
Indian acquires ACE.
Felix Wankel patents his rotary engine. The design won’t make its way into a motorcycle for decades.
Val Page designs his first engine for Ariel of England: a 250cc OHV single.
The Crash of 1929 brings the booming economy to a screeching halt. Black Thursday is the start of a dramatic slide in stock prices that sees the U.S. market lose in excess of $30 billion in a matter of days. The collapse triggers the 12-year-long Great Depression.