PAINESVILLE, OH—His hands held high over his head, Michael Warren jabbed at his thumb with a knife as bright and shiny as the phalanx of motorcycles that surrounded him. Some people in the crowd winced and turned away, but when they looked back again, Mr. Warren still had not managed to tease out the drop of ritual blood.

“Get a sharper knife,” someone yelled, and the rest of the crowd laughed. Finally, Mr. Warren leaned into the effort and brought some blood to the surface. He held up his thumb for all to see and uttered the same words he had said each first Sunday in May for the last 16 years: “Let this be the only drop of blood shed on Ohio’s roads this year.”

Then he bent down and ground his thumb into the dirt track of the Lake County Fairgrounds.

Thus another “Louie Run” was officially declared. It was a far cry from the original, in which Mr. Warren and 60 others gathered to mourn the passing of Louie Ivcovic, the proprietor of a local bar. This year, more than 5,000 bikers participated.

Unlike other bar owners in the county, Mr. Ivcovic had welcomed the bikers and provided them with beer and a place to organize their deer-hunting parties. His biker friends decided to mark the first anniversary of his death by riding in a pack to his grave and then having a big party.

The following year saw more deaths within the biker community, so the group added a few words on their behalf to the Louie Run. The event has grown rapidly since then, and is now considered the kickoff to northern Ohio’s motorcycle season.

In this year’s Louie Run, on May 2, the bikers rode in packs from 12 different sites for the all-day event, which also featured bands, bike games, a tattoo contest, and the wedding of Dennis Slother and Gretchen Bryan, who rode to the ceremony on matching blue Harley-Davidsons and were married by a leather-clad minister. “They had 5,000 people at their wedding,” Mr. Warren said. “Kings and queens couldn’t do better than that.”

But the Louie Run is more than an occasion for bikers to air out their black leather chaps and polish their chrome. The event is also a serious fund-raiser for a number of causes that the bikers hold dear. Last year, Louie Run Inc., a nonprofit charitable organization, gave away more than $24,000.

The Lake County Society for the Rehabilitation of Children and Adults, which provides therapy and socialization to about 6,000 clients, receives the largest amounts. The bikers began making donations to the society in honor of Mr. Ivcovic’s son, who is a client, and have given it more than $50,000 over the years.

“They’re good friends,” Ann Dietrich, the society’s executive director, said of the bikers. “At our annual dinner, we usually have two or three tables of people from the Louie Run in their black leather vests, sitting next to the businessmen and little old ladies who support our program. There’s a long row of their bikes right outside the window so they can keep an eye on them.”

Another recipient of Louis Run largesse is Cleveland’s Rainbow Babies and Children’s Hospital. Each year, the hospital compiles a wish list of toys and art supplies used to entertain patients and their siblings. The Louie Run committee and hospital staff go shopping together, then the bikers arrive in formation at the hospital to deliver the items, visit the bedridden children, and place the ones who are well enough on their bikes. “They arrive in their black leather outfits and the kids just love it,” said Tammy DeMario, a former child life specialist at the hospital.

This kind of teddy bear image is hardly what attracted these bikers to the motorcycle subculture. Most members of the Louie Run committee are burly, bearded men in their 40s who started riding in their teens, drawn to all the mayhem the biker life implied. Now that they are hard-working citizens, they hope the Louie Run will change the minds of those who still see bikers as bad guys looking for trouble.

But they may not want to change minds too much. Committee member Roy Butzer’s tattoos—a skull-faced snake coiling from a scar on his arm and a massive Harley-mounted skeleton gloating on his back—are hardly reassuring images.

“I still like it sometimes when I walk into a room and people move out of the way,” Mr. Butzer admitted, braiding his long black beard, then holding its ragged ends up to the light for inspection. “I must say that I still do.”

Reprinted with permission from The New York Times