leather vests and jackets are emblazoned with diabolic skulls in fedoras and the words "Bay Riders." The club is a registered nonprofit, and was recently on the TV news for donating $1,000 to foster kids. But police don't buy the philanthropic Santa on wheels bit. They say the Riders have many characteristics of an outlaw motorcycle gang, and operate under the control of the Hells Angels.Officer Dan Silver, the gang task force cop who monitors the group with an FBI partner, says the Riders are the biggest Angels support club that sprang up a year ago in response to the murder of Mark "Papa" Guardado. Guardado, the president of Hells Angels' Frisco chapter, was gunned down in the Mission in September 2008, allegedly by a rival Mongols motorcycle gang member.Silver says there are at least 30 Bay Riders members in San Francisco, the North Bay, and the Peninsula. They dock their bikes at hangouts in the Excelsior, SOMA, Dogpatch, and the Embarcadero, and have been advertising their first anniversary motorcycle run on Nov. 8. "To keep the Mongols out of the city, the Bay Riders appeared like wildfire," he says. "A huge new group was formed to increase the number of allied personnel."The Riders first appeared on the cops' radar at their "Break Out Party" one year ago at Jelly's club on Pier 50, which ended in gunfire. The club's manager said he heard a car had driven up to the club, "ghost ridding [sic], wilding out, driving out of control," according to the police report. Someone opened fire on the vehicle and hit the woman passenger in the shoulder. She survived, and police have made no arrests in the case.Silver suspects the Riders "are being tasked with doing things for the Hells Angels," like providing security at events. In late August, SF Weekly talked to a man who identified as a Rider hanging outside Pier 23 on the Embarcadero. He said Riders are required to attend Angels events, and that some Riders were transporting out-of-town Angels to and from the 55th anniversary party of the Frisco chapter that very night."I think there's a strong possibility we're going to see some Bay Riders become Hells Angels," Silver says, adding he had heard at least one Rider was "prospecting" to become an Angel, something akin to rushing the biker fraternity.We requested an interview with the Riders' CEO, but he refused to speak on the record. We did talk to Dominic Guardado, son of the late Mark Guardado, who confirmed that he and his brother are Riders members but refused to discuss any connection to the Angels. "If you put only what the SFPD has to say, people will probably see only see the negative aspects," he said, adding, "We're all about the community. We're not around to intimidate people. We're motorcycle enthusiasts."