Her family and neighbors put up 13 of 18 riders during stopover in Baltimore.

Flannery McArdle, 21, rolled into Baltimore on Aug. 13, on a 4,000-mile bike trip from San Francisco to Boston Harbor to raise money for HIV/AIDS research.

And her first stop, with 17 other riders following, was to her family's house on Uffington Road in Mount Washington. After nearly eight weeks of camping out or depending on the kindness of strangers for housing and food, she could sit down to a home-cooked meal, at a backyard barbecue that her family organized for the bikers.

Thirteen bicyclists in all stayed with the McArdles overnight and the other five stayed with neighbors.

After all the places they've stayed, from churches to bike shops, "We are so good at cramming into small spaces," said McArdle, a Friends School grad, who's now studying sociology and anthropology as a rising senior at Carleton College in Northfield, Minn.

It's been rough going in other ways, too, McArdle said in Washington, the group's current stop.

"We've had over 80 flats. We're constantly working on our bikes," she said.

The bike group started June 18 from Half Moon Bay in San Francisco, home of the nonprofit organization Face AIDS, a global youth movement to fight HIV/AIDS, according to its website, http://www.faceaids.org.

Most of the riders are undergraduate or grad students from around the U.S. Several are medical or pre-med students, McArdle said.

All share a passion for "public health and fighting the HIV/AIDS," McArdle said.

The bikers' goal was to reach Boston, headquarters of Partners In Health, which tries to bring medical care to the poor, according to its website, http://www.pih.org.

Riding an average of 80 miles a day, they expect to reach Boston by Aug. 23.

But they have a bigger mission, to raise awareness and money to fight the virus and its repercussions socially.

"The point of the ride is to lessen the stigma of HIV/AIDS," said McArdle, who so far has raised $6,000, and is hoping for a career in public and global health. The group collectively has raised $80,000 of its goal of $100,000, she said.

The group also wants people to know that AIDS is a continuing problem in the U.S., although most of the attention has been on nations with high HIV infection rates, like Rwanda and South Africa.

But Washington, for example, has a higher AIDS rate than Rwanda, McArdle said.

"A lot of people don't think (AIDS is) a problem in the U.S.," McArdle said.

Though the trip has been physically demanding, it's had many rewarding moments in teaching the public, especially youths, about HIV/AIDS. Bikers talked to a boys and girls club in Cleveland and a youth group at the Omaha chapter of the Nebraska AIDS Project. In Chicago, they were introduced to the crowd before a Cubs-Cardinals baseball game at Wrigley Field.

They have traveled mostly county and local roads in the West and Midwest, often staying in small towns.

"People have been incredibly generous," McArdle said. "Some people have handed us money on the street."

In Baltimore on Monday, they held a late afternoon press conference at the law firm Gallagher, Evelius and Jones.

And on Tuesday, they headed for Newark, Del.

McArdle was in high spirits. She said her legs tired at the beginning of the ride.

"Not so much anymore," she said.

And she was energized by her message.

"We need to start the conversation," she said.