Yes, they are. A friend of ours was a biker gang member, knew him since high school. He got in a lot of trouble over the years, in fights, and sometimes ended up in jail. But he was very good to us. When I was having a problem with a bad neighbor, he offered to have his biker gang show up and harass the bad neighbor. I declined, for the sake of my good neighbors. He passed away a few years ago and I miss him. Memories of him lending his chopper to me to ride, and him showing off all his guns. Bikers will fight hard to defend their friends.
My wife, in her younger days, lived in a neighborhood where the Hells Angels maintained a clubhouse. The Angels did not want a lot of police presence, so they put out the word that there would be no crimes like muggings or robberies tolerated in the neighborhood.
Crime was very low.