In my humble opinion, the greatest invention of the twentieth century was the bicycle derailleur shifting system.
This invention made the bicycle a realistic mode of transportation in a variety of terrains.
Average people with a few weeks of practice can travel on a modern multi-speed bicycle on moderately hills roads at an average speed of around 13 miles per hour. With improved fitness a normal adult can average 15 miles per hour. This makes daily commutes of 7-10 miles realistic.
Of course elite athletes race up steep mountains at speeds over 20 miles per hour, and they descend the other side of the mountain at 50 mph or more.
Before the derailleur was allowed in the Tour de France in 1938, racers had two gears, one on each side of the rear wheel. Just before entering a mountain stage, for example, they could pull over, remove the rear wheel and flip it around. In those days riders didn’t have support teams. They had to carry tools and supplies in their pockets with spare tires slung over their shoulders.
Tullio Campagnolo invented the quick release in 1927 after frozen fingers prevented him from turning the wing nuts to release his wheel so he could flip it around. He went on to found a bicycle parts company that eventually perfected (though they did not invent) the derailleur. The device itself began to appear as early as 1905. Its predecessors included complex systems of levers and pulleys.
The bicycle was invented early in the 1800s. Hundreds of bicycle companies rose up in the United States. By 1900 there were two large patent offices in the nation’s capital. One was for bicycle inventions, the other was for everything else.
Susan B. Anthony once said,
The bicycle has done more to emancipate women than anything else.
The bicycle could also do a lot to emancipate us from dependence on oil. The author’s of the book Bicycle Science estimate that a human powered by the equivalent number of calories in a gallon of gasoline could travel about 1000 miles. Or, drinking milk instead of gasoline (remember milk is over 90% water) a rider could go about 99 miles. If riders neglected to replenish all those calories, cycling could also help liberate us from the plague of obesity and diabetes.