AMSTERDAM — Eight British bankers in orange jumpsuits, their ID patches embroidered with the names of Tolkien characters, were in town for a bachelor weekend (Frodo was getting married). They had just finished a two-hour city tour on a beer bike. “Arwen fell off!” said a very cheerful Pippin. “He almost killed himself!”

“We had girls running after us!” Gandalf said.

“Well,” Pippin pointed out, “they wanted a lift.”

“Still,” said Aragorn, the best man, “we talked to women. It was great.”

A kind of pub on wheels, propelled by pedaling, the beer bike — which in Europe is usually but not always steered by an employee of the tour company rather than by one of the partygoers — is thought to have been invented in the Netherlands in the late 1990s.

But in recent years, the contraption, variously promoted as a social lubricant; an original, environmentally correct way to see a city; and a healthier, calorie-burning alternative to sitting in a bar, has expanded its appeal beyond the Dutch border to several European countries and the United States.