NEWRY – A leisurely three-day bicycling tour through rural Maine might seem like a laid-back weekend, but the participants of the Trek Across Maine know that the event is for a cause.

Almost 2,300 cyclists registered for the event, which started Friday morning at the Sunday River Ski Resort with a 65.5-mile ride to the University of Maine at Farmington. The ride, which benefits the American Lung Association of Maine, will cover 104 miles in the next two days before concluding in Belfast.

Ed Miller, executive director of the association, said the event has grown in scale since it started 24 years ago. He said a presentation is made on Saturday night, after the second day of riding, to let participants know what their fundraising efforts will benefit.

“They are really committed to the mission of the organization,” Miller said. “Here people really understand why they’re raising the money.”

Riders are required to raise a minimum of $500 to participate in the trek, though Miller said cyclists raise about $750 on average. He said the association will likely raise close to $1.5 million this year.

The American Lung Association, which was founded in 1911, promotes lung health and lung disease prevention through research, legislation and education. It has done battle with tuberculosis and supported anti-tobacco measures, including the ban on smoking in Maine’s restaurants.

Currently the organization is pushing to improve the quality of the state’s air. To that end, the Department of Environmental Protection donated a hybrid pace car to see riders off, and a record number of participants took buses or carpools to the event.

Several veteran trekkers had the issues in their mind as they saddled up for Friday’s leg. David Drown, principal at Meroby Elementary School in Mexico, said SAD 43 had raised $1,200 from a penny drive. He cited the anti-tobacco and air quality efforts of the association as areas the district supports.

“We hear that from our kids, they’d like their parents to stop smoking,” said David Walton, a counselor at the school.

Robert Ginn of Pownal raised $1,120 for his third trek. Ginn said he initially rode in the trek after he was challenged to do so, but became more involved when he found out about the causes it supports. Ginn said he is a former smoker, his brother is a current smoker, and his father died of chronic obstructive pulmonary disease.

“That’s quite an incentive,” he said.

Melissa Rockwood of Ellsworth said she was riding in her fourth trek because several members of her family have lung health issues.

“I’m hoping that after I’ve done this enough times my mother will quit smoking,” Rockwood said.

Andy Greif, executive director of the Community Bicycle Center in Biddeford, said he was participating in his ninth trek, and that the 30 cyclists associated with the center had raised over $16,000 this year. Greif said the center, which provides youth development programs to middle school children, is also something of a beneficiary of the trek, as it has received funds for tobacco cessation programs.

Though the ride was for a serious cause, it still provided a chance for some fun. The Maine Blackfly Breeders Association, a nonprofit organization that gives money to Washington County charities, distinguished itself with black fly dolls atop their helmets.

Greif was one of four riders on a quad bike, not counting a squawking rubber chicken labeled “le poulet de la velo” (“the Chicken of the Bike”). Lauren Leboux, a volunteer at the Community Bicycle Center, said the name arose out of one trek ride in which she combined her French with random chicken calls.

“The name of it is a running theme for the past few years,” Leboux said, “but the chicken is new.”