WATERVILLE — More than 2,000 bicyclists left Colby College on Sunday morning as they began the final 55-mile leg of the Trek Across Maine, a three-day ride and fundraiser for American Lung Association.

Many of the cyclists wore plastic bags on their helmets and wrapped them around their gear as a steady rain fell. The Trek, which began Friday at the Sunday River ski resort in Newry, is a 180-mile ride that concluded Sunday at Steamboat Landing in Belfast. This was the event’s 31st year, and it drew more than 2,000 cyclists, including 136 teams.

“The camaraderie is great,” said Kenny Young of Newry. “Everyone is really supportive, and it’s very uplifting.”

Young, 28, was a member of Team Maine Adaptive, put together by Maine Adaptive Sports & Recreation, the first adaptive ski organization in Maine for people with physical disabilities. The team included Young and another hand cyclist, Larry Nadeau; two amputee riders and three support riders.

After spending the night in Waterville, the team and others gathered in the Alfond Arena at Colby, surrounded by the click- clack of biking shoes on the cement floor and the hiss of air being pumped into bike tires, at around 7:15 a.m. Sunday. They took a quick team photo and said a prayer before heading out.

“It’s actually simpler than most people think,” said Corey Hamilton, of riding with a prosthetic. Hamilton, of St. Albans, had his left leg amputated below the knee last summer, the result of a car accident in 2001 that caused trauma to his leg not correctable after multiple surgeries, he said.

This was his first time riding in the Trek. The prosthetic does not breathe easily, so Hamilton, 29, and his friend Patrick Brown of Pittsfield, who is also an amputee, usually stop at rest stations along the way to take a break and let the devices air out.

Brown, 32, lost his right leg below the knee in a skydiving accident in 2009. “It changes what muscles you use, like while most people are doing a lot of work with their calves, we’re using our hamstrings and quads more,” he said.

“As an athlete you’re always trying to push yourself, and it can be a little harder,” he said.

“But it’s worth doing,” added Hamilton.

Many of the 2,050 cyclists registered for the event were also riding in support of lung health. Participants are required to raise at least $550 each for the American Lung Association.

Sisters Sarah Dawson of Yarmouth and Elizabeth Dawson Holland of Gorham were riding in memory of their mother, Judy Dawson, who died of lung cancer in September.

According to the American Lung Association, lung cancer is the leading cancer killer in both men and women. An estimated 158,040 Americans are expected to die from lung cancer in 2015, a number that accounts for about 27 percent of all cancer deaths, according to the association.

The sisters said their mother was a smoker for 30 years, a factor that may have contributed to her lung cancer, and they are hopeful that more people can stop smoking. They said they could feel their mother’s presence on the ride through the bells that volunteers rang to cheer them on.

“I feel it today, but I also feel ready to go,” said Sarah Dawson, 46, as she hopped on her bike and prepared to head out into the rain.

Nearby, Mark Reinsborough, also of Yarmouth, said he was riding in memory of his grandfather, who died of chronic obstructive pulmonary disease, or COPD. Also known as emphysema, COPD makes it hard to breathe. It is the third leading cause of death in the United States, and is commonly caused by smoking or breathing dirty air.

Reinsborough was riding with his fiancee, Betsy Peixotto, who he said has been doing the Trek for six years and got him involved in it. This was his second ride.

“I’m a little tired but I’m still excited to go,” he said. “I really like the camaraderie. It’s like a rolling party for 180 miles.”