His evolution from a small-town tinkerer to an industry titan reflects greater shifts of Taiwan and its economy. Once a workshop to the world, anonymously churning out bikes, cellphones and computers for big-name foreign companies, Taiwan now has firms like Giant, HTC and Acer that have become global brands in their own right. With those successes come new questions about whether those businesses can continue to lead and innovate.

For Mr. Liu, the answer is not just selling more Giant products (though his cycling advocacy campaign certainly helps with that), but focusing on how bicycles can reduce pollution, make people healthier and help cities function better. “It’s been amazingly successful P.R. for his company, but he’s not only doing it for that,” said Ho-chen Tan, former chairman of Chunghwa Telecom, Taiwan’s largest phone company, and a regular cyclist. “He’s showing that even people his age can do this. His encouragement and commitment is a driving force for people to follow.”

Mr. Liu’s transformation, and that of many of his cycling compatriots, was motivated somewhat unexpectedly by a 2007 film, “Island Etude,” about a young man who bicycles around Taiwan. “With some things, if you don’t do them now, you might never do them in your life,” was its most often repeated line.

“I saw the film and thought, that line, it’s criticizing me, isn’t it?” Mr. Liu said. “I was 73, and I thought if I don’t ride now, I’ll never be able to do it.” So he took up the film’s challenge, planning a circumnavigation of Taiwan.

He trained for six months, but admits that was not enough. Images of the 2007 ride show his round belly pressing against his jersey, his face locked in a scowl. “Oh, that trip was really miserable,” he said. “I had back pain, sleep apnea, high blood pressure and so on. Old people’s problems.” At one point he was knocked down by a car and scraped. But he persevered, finishing 575 miles in 15 days.