British bicycle troops in India, 1920s.
(c) Anthony Cox, http://www.blacktriangle.org
As the number of bicycle riders increased among the general population in Europe and North America, so did its application in commercial and military ways.
During WWI and WWII, armies from many nations fielded bicycle-mounted troops, and a passage from Ernest Hemingway's Farewell to Arms describes the main character's encounter with a unit of Germany Army soldiers on bikes:
"Look, look!" Aymo said and pointed toward the road.
Along the top of the stone bridge we could see German helmets moving. They were bent forward and moved smoothly, almost supernaturally.
As they came off the bridge, we saw them. They were bicycle troops. Their carbines were clipped to the frame of the bicycles."
Over the 20th century, bicycles have been adapted to haul heavy loads over long distances, particularly in third-world countries, and even today in the world's crowded cities, bike messagers and pedicabs play a valuable role in moving people and packages in the most efficient means devised to date.