Hauling down the California coast on a Trek 400 bike, Lin Bruce tried to forget the pain pounding in her 60-year-old body.

She had never ridden a bike more than 10 miles before, and here she was, cycling across the United States with a group of strangers in 1999. No cellphones. No end in sight.

So, to the tune of “Down in the Valley,” she began to sing in her head: “I’m out here riding, riding my bike/And at this moment I’d rather hitchhike … There is question, a question for me./Why I do this? It sets my soul free.”

Never an athlete, Lin was born in Cheyenne, Wyo., “way before Title IX.” Women usually held important, but limited roles — secretary, nurse, teacher or mom. It was easy to feel small, Bruce said.

She had spent her life raising four kids, moving from city to city, country to country, to follow her husband’s career. She had just watched her sister-in-law commemorate her 60th birthday with only a lunch date with her mother.

Bruce, then 59, felt stuck.

“I wanted to pop out bigger, before I was too old to pop out bigger,” Bruce said. To burst out of the feeling that she couldn’t grow as a person anymore.

She shifted gears and sought out a challenge. Bruce came across a newspaper ad for WomanTours, promoting a bike tour from California to Florida for women over 50. The trip started on Lin’s 60th birthday. “Oh, that’s it,” she thought.

The winter before the trip, Bruce mounted a stationary bike in her Northfield home and pedaled without a formal training plan. On the eve of the trip, her momentum flagging, Bruce broke down and cried in a San Diego hotel room. Then, for two months, she rode.

Two weeks into it, chapped from pedaling against Texan headwinds, she lost faith in what she was doing. “Is this fun?” she wondered. “I’m doing this for my birthday?”

Eventually, though, the voices fell away. Her muscles strengthened, and she rolled up in St. Augustine, Fla., as a woman truer to herself, her husband, Bob, noticed.

“I don’t shut myself off as quickly or as finally as I did earlier in my life,” Bruce said. “Somehow it translates if you can ride 3,000 miles, you can probably do something else.”

Bruce, now 77, has since cruised through the country: the steamy South and the dewy Pacific Northwest — and part of Great Britain, too. She’s logged 18,000 miles, pedaling the Great Plains and hugging the coasts along the Great Lakes. On trips, she bikes about 50 miles daily; each leg lasts six to seven hours.

It’s satisfying “to get there at my own steam,” Bruce said.

Since they traveled more than 800 miles to Cheyenne on two wheels to Bruce’s 50th class reunion in 2006, Bob often bikes and drives alongside Bruce, carrying the supplies. They left their home on June 24 to bike to her 60th class reunion, arriving healthy but tired on July 7.

She didn’t tell most of her former classmates about her mode of travel last time. “I didn’t want to be taking on something grandiose that I would be embarrassed about if I fell on my face.”

Now, Bruce is a motivational speaker for audiences of mostly older, female Rotary Club members. Her mantras are simple: Make the commitment. Power through. Find humor. Ask for help. Work with others.

A stranger recently overheard her discussing one of her trips and approached Bruce. She said she was a survivor of a past trauma, and thanked Bruce for making her realize “it’s not over until it’s over.”

“If my story touches even one person with a sense of possibility, then I want to tell my story,” Bruce said, as she began to cry softly.

So this class reunion, “I’m not being quiet,” Bruce said.