Sunday night, the riders were spotted by Lombard Street. That has raised a lot of questions about what's being done to stop them. People say it's dangerous, but the riders keep getting away with it.
"It's just a block up there - up Lombard Street, at the bottom of the curvy street," said Sanee Iqbal.
Iqbal couldn't believe what he saw Sunday night at Lombard and Leavenworth streets in San Francisco.
"It was probably 15 plus of actual bikers," said Iqbal.
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Iqbal captured video of the bikers coming down Lombard Street just before 6 p.m.
"The bikers are coming down the hill and just honking," said Iqbal. "Later, that's when I see the one, two three bikers starting to circle - doing wheelies and kind of burning rubber around the officer there."
Bikers circled an officer who's there to help direct traffic.
"I just found it interesting that it would happen with an officer," said Iqbal. "They were definitely antagonizing."
Iqbal said no police ever showed up. No one was arrested.
Tourists who saw the video of the bikers find it hard to believe.
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"They are a little crazy. I don't know what to say. They were just doing it up there," said Giulia Moro, a tourist form Italy.
We showed Bernard Goethals the video of the bikers at Lombard Street.
"It was the same guys I saw yesterday at Fisherman's Wharf!" said Goethals.
He and his family are visiting from Belgium and were shocked by what they saw at Fisherman's Wharf. He even got pictures of it.
"Motocross cyclists who wore masks, didn't wear helmets, you couldn't recognize their faces and they were doing all wheelies on the footpath and bringing the tourists in danger," said Goethals.
Iqbal and other San Francisco residents say they've seen and heard the rowdy bikers before -- along the Embarcadero, on the Bay Bridge, and by the Palace of Fine Arts.
"People can get away with stuff," said Iqbal.
All the activity raises questions and concerns.
"I was thinking why have not been stopped by the police," said Robert Brown, who's visiting from the U.K.
This afternoon, the San Francisco Police Officer's Association released this statement from Lt. Tracy McCray:
"San Francisco police officers would like nothing more than to arrest each and every individual shown wreaking havoc on our streets in those videos. They are nothing more than a bunch of bullies on bikes. They purposefully put the lives and safety of innocent drivers, cyclists, and pedestrians at risk. The challenge with being short over 600 officers is that we do not have the officers on shift we need to instantly respond with the number of officers needed to safely curtail a large group acting with aggression to both bystanders and responding officers. If we had the number of officers we should have, you would have seen a lot more of those bullies in cuffs."
A CHP spokesperson told me they have seen motorcyclists doing wheelies and doing donuts on the Golden Gate Bridge. And they have arrested some of those riders for reckless driving, impeding traffic, unlawful assembly and exhibition of speed.