Professional cyclists from all over the world hit the starting line this Saturday in the first stage of the unrelenting, three-week-long Tour de France. Starting in Utrecht, Netherlands, the epic course will cover a total of 3,360 kilometers (about 2,088 miles), raced in 21 daily doses called stages, through gusting winds, up steep mountains, and at breakneck speeds down harrowing hairpin turns.

This year marks the 102nd tour held since the inaugural 1903 race. In the pre-Spandex era of the Tour’s early days, bike frames were made of heavy steel, and riders handled their own repairs, carrying extra tubes and tires wrapped around their shoulders and waists.

Historically, bicycles have served many roles—from military transportation to an emblem of the women's rights movement in the United States.

And they come in all shapes and sizes—from steel-framed workhorses to featherweight carbon fiber racing machines.