In April, May and June, spandex-clad riders dip their rear tires into the Pacific and head east for the Atlantic. In July, August and September, riders who started on the East Coast begin rolling into Florence, salt-stained and wind-burned, but clutching an accomplishment as surely as they clutched the handlebars along those thousands of miles of highways.

"Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover."

Mark Twain

On May 10, Mike and Tracy Stallard dipped the rear tire of their tandem bicycle in the Chesapeake Bay in Yorktown, Va. On a warm, windy day in late August they wrestled that same bike across the sand in Florence and dipped the front tire in the Pacific Ocean.

In between those bookend events, the Stallards completed a 4,000-mile odyssey across America, joining an estimated 2,000 people who make the continental crossing by bicycle each year.

A large percentage of those modern-day adventurers either start or end in Florence, the western terminus of the TransAmerica Bicycle Trail.

In April, May and June, spandex-clad riders dip their rear tires into the Pacific and head east for the Atlantic. In July, August and September, riders who started on the East Coast begin rolling into Florence, salt-stained and wind-burned, but clutching an accomplishment as surely as they clutched the handlebars along those thousands of miles of highways.

Linda DeSitter, an emergency room physician from Hood River, knows that feeling well. She, her husband, Lou, and two of their three teenage children spent much of the summer of 2006 crossing America by bicycle, starting in Maine and ending at Florence.

"If you ask my daughters what they did all summer, they'll say they stopped every three miles and waited for mom to catch up," jokes Linda DeSitter.

Their journey was conceived six years ago, after Linda and Lou backpacked the Pacific Crest Trail through Oregon with their children, who were 9, 11 and 13 at the time. Excited by the successful adventure, the family began to plan another. Their encore turned out to be a bike ride across America.

The logistics of the bike trip consumed the family for months. "We had lists everywhere," she says. "We had it all planned out, where we'd meet people, where we'd stay."

It took her a year to find other doctors who could take her shifts at Providence-Hood River Memorial Hospital. Then there was the matter of school. The family had a finite window of time to complete their crossing in order for daughters Teresa and Sara to make it back for soccer practice.

"We flew to Maine the day after the kids got out of high school," she says. "We had already airmailed our bikes to a bike shop in Maine, and they had them assembled when we arrived. We pedaled a mile to the ocean, put our back tires in the Atlantic and then rode across the country."

Michelle and Jim Henrichsen, a retired couple from Grand Rapids, Minn., started their cross-country bike trip in Yorktown, Va. on May 9. By the time they reached Oregon in August, they had crossed paths with dozens of other TransAmerica riders. On some days, they said over lunch in the eastern Oregon town of Dayville, they passed eight or 10 cyclists a day heading the opposite direction. Sometimes they passed or were overtaken by riders going the same direction.

"It's like a telephone line out there," says Mike Stallard, who ran into the Henrichsens a couple times while he and his wife, Tracy, rode their tandem. "We'd hear about other riders and things that were happening hundreds of miles ahead of us."

The Stallards, who live in Southern California, decided to make their journey two years ago, after hiking the John Muir Trail through the Sierras. Mike, 37, who works for a geothermal energy company, passed up a chance to ride across the country with a friend when he was 19.

"I had to man up and do the right thing," he says of that decision. "I had to get a job."

Eighteen years later, he still felt pangs of regret over missing that trip. It was Tracy who suggested they take time off from their jobs and fulfill the dream. Tracy, an occupational therapist, lost her parents recently. She says that loss, combined with her job working with disabled people, made her keenly aware of both the frailties of the human body and the vagaries of time.

"We realized we had to do this while we can," she says.

Motivation for the riders can come from many places, even their own imaginations.

"I have this fantasy," says Mike Aris, a 59-year-old retired school psychologist from London who flew to America and completed a solo crossing in early August. "There might be an afterlife. There might be a day of judgment. And I might die.

"Then I might get to stand before St. Peter or some geezer who looks at a big book and says, 'Right, Mike ... . Let's see ... I let you retire with good health, good money, and a bloody good bike, a Dawes Super Galaxy with Reynolds 853 tubing. I'd like one of those myself, but you can't get them up here. And what did you do with these gifts? Hmm ... I see you stopped at home and watched daytime TV. Well, as you are so fond of TV, you can spend the rest of eternity watching it.'

"Or," Aris continues, "If he sees in his ledger that I tried to explore the world I was given, he might let me spend the rest of eternity exploring the universe. It might not happen, but it is a chance worth taking."

Reach features editor David Smigelski at 776-8784, or e-mail dsmigelski@mailtribune.com