Thirty-one Duxbury residents will be competing in the 30th Pan-Massachusetts Challenge this August to raise money to fund cancer treatment and research.

The PMC takes place Aug. 1 and 2, and covers several different routes from Wellesley or Sturbridge to Provincetown. Participants are required to fundraise a certain amount of money, depending on how many miles they ride.

PMC gives 100 percent of its rider-earned donations to the Dana-Farber Cancer Institute, through the Jimmy Fund. Last year’s donations totaled $35 million. To date, the charity has raised over $239 million, according to the PMC Web site.

“PMC is the most efficient charity in the world,” John Coughlin, a cancer survivor and cyclist said.

In 2003, Coughlin’s 21-year-old daughter, Sarah, was diagnosed with cancer. A month later, Coughlin received the same news. The two spent the next year battling cancer through surgeries and chemotherapy at the Dana-Farber Institute in Boston.

The institute consists of two buildings that are connected by The Pan-Massachusetts Challenge Bridge to Progress. This pedestrian bridge was dedicated by the charity in 1997, and is filled with pictures from the race. Coughlin walked through this bridge for nine months while attending weekly chemotherapy sessions.

“At the end of treatment, when I was really weak, I decided I was going to ride in it,” Coughlin said.

This will be Coughlin’s fifth year riding. He will be accompanied by his daughter Sarah this year as well.

There are several possible routes for cyclists to choose from at the PMC. The original and longest route runs from Sturbridge to Provincetown for a total of 192 miles. The shortest route is a loop in Wellesley that is 47 miles long. There are seven total routes to choose from, all of vairying distance and difficulty.

For some athletes, the PMC is about helping others. This year will mark Duxbury resident Skip Sullivan’s fifth PMC as well.

“I have a lot of blessings, this is a chance to give back,” Sullivan said. Nine years ago, Sullivan  began participating in triathlons and heard about the PMC from other athletes he often trained and competed against.

“It’s an emotional ride,” Sullivan said. World class athletes ride beside cancer patients, survivors and doctors. Sullivan recalls one special fan, who every year is at a rest stop on the second leg of the trip.

“He has a sign that says ‘I’m 7-years-old thanks to you.’ That’s pretty moving for everyone.”

Cyclists are also able to ride as teams. “Team Jim” is an eight member team with seven of its riders coming from Duxbury. Team members include Sharon Fownes, Sam Butcher, Ed McGovern (Norwell), and the Rayfield family - Corrigan, Ali, Wendy, Mark, and Al. The team rides in honor of Jim McClure, a Duxbury resident who is battling cancer.

Three generations strong, the Rayfield family makes up over half of the team. Mark Rayfield has been riding in the PMC for the past 15 years, while it’s his son Corrigan’s first year at 15. Mark’s mother is a  breast cancer survivor, while his father, Al, is 74 and still riding in the PMC.

With three kids, Wendy Rayfield has found it hard to ride with her husband in the past, but with her children getting older, it has become an annual family event. This will be her fourth  year riding.

As each of the Rayfield children becomes eligible at 15, they join the cause. Her daughter, Ali, has been riding in the PMC for the past three years. Son Corrigan celebrated his 15th birthday on July 1, and this will be his first year riding. At 13, the Rayfield’s youngest looks forward to riding in the PMC as soon as he turns the correct age.

“Just the fact he’s doing it is so great,” Wendy Rayfield said. Team Jim will be riding the two-day, 163 mile Wellesley to Provincetown route.

George Johnston is one of the oldest cyclists in the PMC. At 76, this is Johnston’s 16th consecutive ride.

“I’ve had a lot of people [in my life] inflicted by this awful disease,” Johnston said. Johnston’s own son was treated at Dana-Farber when he fell and was paralyzed at the young at of six. Years later, Johnston lost one of his closest friends to prostate cancer. “I feel it’s payback time,” he said.

Over the past 15 years, Johnston has raised around $100,000 through the PMC. His donations average about $7,000 every year.

Riders have found that even with a tough economy, people are still willing to give to the cause. For the two longest routes, participants are required to raise a minimum of $4,200. The minimum for the shortest route is $1,000.

“People are exceptionally generous, even with the economy so down,” Coughlin said.

“Everyone in New England, and especially Boston, knows about the Dana-Farber Institute and Jimmy Fund and is willing to support the cause,” Johnston said.

It’s hard to imagine biking nearly 200 miles across the state, but for these and other residents, it’s a yearly event. Months of preparation, both physically and mentally, is required to reach the finish line. But ask anyone about their experience, and they’ll be the first to tell you that everything was worth it.

“It’s an incredible experience,” Wendy Rayfield said.