Helmet: Check. Sunscreen: Check. Matzah: Check.

On April 19, 13-year-old Hart Moss pedaled out of New York's Central Park on the ultimate road trip — bicycling to San Francisco.

It was the third day of Passover when he began his journey, his father, David, and siblings Evan, 11, and Starr, 8, pedaling at his side. And on Monday, 4,000 miles, 16 weeks, more than a dozen blown-out tires later, he crossed the Golden Gate Bridge with Starr, Evan and chaperone Charlie Herbert.

"It was definitely an exodus," his father David Moss said from his home in Whitefish Bay, Wis., a suburb of Milwaukee. "It was his passage to freedom."

It was also his bar mitzvah social action project.

Like many congregations, Milwaukee's Reconstructionist Congregation Shir Hadash requires b'nai mitzvah to demonstrate social awareness. Most volunteer at a soup kitchen or spend time at a retirement home.

But on Jan. 28, Hart announced to the congregation that he would pedal cross country, collecting pledges for two charities.

Many congregants smiled politely and nodded their heads. But some, those who knew Hart, "knew to take it seriously. This wasn't just a 13-year pipe dream," his father said.

In fact, Hart's first long distance bike trip was from Milwaukee to Washington, D.C., when he was 9.

There were no PowerBar protein blasts or marathon practices for that ride or this one. "I just rode to my friend's houses," the wiry cyclist said shyly.

Hart isn't certain how much money he raised for the Sierra Club's Inner City Outings, a program that takes urban kids on outdoor trips, and the national Alopecia Areata Foundation, which raises money to fight the disease that results in unexplained hair loss and baldness. But he's certainly devoted to both of them.

Pointing to the fray of blonde hair peeking out under his baseball cap, he said, "I've got alopecia. This is a hair piece. It helps my helmet stay on better."

"Some kids don't get the chance to do all the things I've done," he added Tuesday at San Francisco's Ritz Carlton Hotel. (His suite was paid for by the hotel.)

Each morning, sunrise broke Hart and Starr's campground slumbers and set them on course for five to 100 miles a day. They pedaled from New York to the nation's capital, onto the cornfields of Iowa, the volcanic plains of Idaho, the coast of Oregon and finally to California. Attached to their mountain bikes were mini-trailers laden with pots and pans, sleeping bags, clothing, water and matzah — at least in the beginning.

The boys' mother, Colleen Beaman, hoped her sons would end the ride in Oregon — but they insisted on crossing the Golden Gate Bridge.

"There's something symbolic about going from New York to San Francisco," Hart said. "It just didn't seem right to stop on the Oregon coast. There's just something about the Golden Gate Bridge."

He crossed the bridge over the San Francisco Bay Monday at about 1:30 p.m.

"It was so windy," he said.

Hart drew his inspiration from Louie and Temple Abernathy, 11 and 7. The two brothers crossed the United States alone on horseback in 1911.

"And what was good for Hart was good enough for Starr," Beaman said, explaining how Starr got in on the act.

Unlike the Abernathy brothers, the Mosses were accompanied by an adult at all times during their 16-week trip. Their father started them off, an aunt met up with them to cross the Mississippi River, a 68-year-old former triathalon contender rode with them through Iowa and Nebraska, and their sister Evan caught up with them again in Oregon.

And unlike their predecessors, the Mosses completed their homework by campfire light and sent assignments to their schools in Whitefish Bay.

Hart located other adult companions, including paid chaperone Charlie Herbert, 29, with the help of California writer John Siegel-Bottner. Hart called the author of "Hey Mom, Can I Ride My Bike Across America?" and asked if he'd like to accompany him on a pedaling tour. Siegel-Bottner declined but provided Hart with the names of some people who might.

Herbert, a high school teacher who recently moved to Minneapolis, met Hart and Starr in Casper, Wyo. Although Herbert has led several summer youth biking tours, the Mosses are by far his youngest riding companions.

"I feel a bit like a surrogate parent," Herbert said, as he pulled a piece of unidentifiable "goo" from Starr's hair. And like a father, he sang to them along the way — Arlo Guthrie and Neil Young songs.

Following a week of Bay Area exploring Herbert will load the kids and their bikes into a van he'll drive back to Whitefish Bay. Perhaps he'll croon the "Motorcycle Song" again.

"I don't know. I sing pretty badly," he said.

"Yeah," the Mosses agreed.