LIVERMORE -- The 30-or-so young bicyclists who rolled gratefully into Livermore on a recent Saturday afternoon weren't just weary from an afternoon's ride.
They were making their next-to-last stop on a 4,176-mile commitment to not just bike across the country but to build and promote affordable housing along the way.
The riders, age 18 to 28, were part of Bike and Build, a 10-year-old nonprofit dedicated to supporting affordable housing throughout the country.
Based in Philadelphia, the group organizes eight extended bike trips through different parts of the United States each summer.
Each of the eight groups follows a strict itinerary, sometimes riding all day, sometimes stopping at predetermined sites to work alongside local affordable housing groups building homes.
Riders, most of them college or graduate students, spend the nights at churches, community centers and schools along the way.
This is the second summer the riders have spent the night at Asbury United Methodist Church, said facilities manager Mitchie McCammon.
"I didn't know what to expect when they showed up, but they're just great, they have this great spirit," she said. "I just think it's a great organization. These kids are so amazing, so driven and doing a great thing."
The group that arrived in Livermore left Charleston, S.C., on May 25 and finished their ride Aug. 11 in Santa Cruz.
During their 82 days on the road, they passed through Georgia, Alabama, Mississippi, Arkansas, Oklahoma, Texas, Colorado, Utah, Idaho and Oregon before entering California.
They endured lightning, hailstorms, extreme heat, high wind and a traffic accident that sidelined two riders.
"We have 17 build dates in 11 cities," said Dave Shirk, 27, one of four group leaders on the ride. "We stay a day in most areas. In Oklahoma City we stayed two days and helped in Moore, which was devastated by a huge tornado. We were building a home near the high school. Then we had a seven-day build in Colorado."
In addition to working on homes and promoting the idea of affordable housing, Bike and Build provides funding to various projects around the country, much of it raised by the $4,500 donation each rider contributes.
To date, approximately $4.5 million has been distributed to various affordable housing groups around the country.
There also is an emphasis on recruiting and developing community-oriented young people with a long-term interest in affordable housing issues.
"We want to help create civic-minded young adults who are leaders in their communities," Shirk said. "It's important for young people to be exposed to this kind of adventure and to help out and learn about these issues ... When we have build days we bring a lot of energy. We don't want to be idle. We've been told by groups that we catch them up on projects and bring them back on schedule."
The bicyclists rolled up to Asbury United Methodist in small groups, each rider dusty, sweaty and smiling.
Molly Junck, 26, of Sunnyvale is one of the team leaders. A graduate of Brown University in computer science, she works at Adobe Systems. Few of the riders know much about either bike touring or construction before they join the ride, she said.
"It's a life-changing experience," she said. "We're doing this enormous community service project ... living off the generosity of other people and seeing another side of humanity that is so generous. It's the neatest way to experience the country and see what's out there."
The long weeks on the road can be a defining experience for the participants, she said.
"You discover your limits ... it's a good way to get to know yourself," she said. "And because it's an organization of young people, it definitely changes some careers."
For more information, log on to www.bikeandbuild.org. The site includes information on the organization as well as details on the various routes, photographs and blog entries by the riders.