Last fall, Spencer Matson couldn't run three miles.

This summer, he plans on tackling 4,000 miles as part of a cross-country bike trip that benefits the Ulman Cancer Fund for Young Adults.

Over the course of 70 days, Matson, 21, and 30 others will travel across the country, stopping along the way to meet young adults afflicted with cancer, as well as spreading awareness of the organization.

"It's going to be a very daunting task," said Matson, who also is one of the ride directors. "You take it day by day, and you go out there and you know where you're going to be at the end of the day, regardless of the obstacles along the way."

Matson's trip will be dedicated to Bob Dennis, 82, who became a mentor to Matson during his time with Post 53 Emergency Medical Services. Dennis is a four-time cancer survivor and is in remission from bladder, skin, prostate and bone cancer.

"Over the course of the year, he became a strong mentor for me," said Matson, who grew up in Darien and was appointed vice president of operations at Darien High School during his senior year.

More Information

Fact box

The ride, called the 4k for Cancer, starts June 2 in Baltimore, where the team will begin the trip with a dipping ceremony, which involves putting the back tires of their bikes in the Atlantic Ocean. Once the team members reach the Pacific coast, they'll dip their front tires in the ocean.

There will be days when Matson and his team will be biking 100 miles; other days, they'll be climbing mountains.

"You find the strength somewhere and you do it," Matson said.

In 2012, the 4k for Cancer trip, which included 88 riders, raised $500,000 for young adult cancer research.

The inaugural ride was in 2001 when a group of students from Johns Hopkins University set out in an effort to raise funds for cancer awareness and complete a goal of biking across the country. The past three years have been done in corroboration with the Ulman Fund for Young Adults, which has been providing education, guidance and support for young adults diagnosed with cancer and their families since 1997.

Dennis, who will be 83 next month, has been a volunteer with Post 53 for 38 years. Of the hundreds of teenagers that he has worked with, Matson was a standout Post 53 member, Dennis said.

Since Matson has gone away to school at Tufts University, where he is a senior, there will be times that the director of the Post 53 corps would say to Dennis, "This guy's not Spencer," when talking about some Post 53 members.

"I like them all, but it's true Spencer's extraordinary," Dennis said.

Whenever Matson is home, he and Dennis get breakfast at the Sugar Bowl, something Dennis doesn't do with anyone else Matson's age.

There are four possible routes for the 4k for Cancer trip that Matson can take, but when he asked Dennis which one he should tackle, Seattle was the answer. Dennis' father grew up in Seattle before coming east and Dennis has never seen it.

" `Take some pictures of Seattle,' " Dennis said he told Matson. "I probably won't get to see it."

Regardless of the reasons for taking the trip, Dennis laughed when he asked what he thought of Matson's adventure.

"I think he's crazy," Dennis said. "I can never imagine pedaling that far. But he's got the grey matter to do it, the body and the will.";203-972-4407;@Meg_DarienNews