Adults race kids' tricycles and more in San Francisco

STORY: For two hours, racers donned their finest costumes and pedaled to the metal as they took hair-raising turns down and around an approximately 700-foot (213 meters) section of Vermont Street in the Potrero Hill neighborhood before hundreds of screaming spectators.

"Love the speed. It feels much faster than it looks," said Bonnie Black, who lives in Boston, Massachusetts. "So it's incredible to be down there and feel like you're going very, very fast."

The event is a free, all-ages, annual neighborhood event with the only rule being that the big wheels or tricycles “are made of plastic with plastic wheels.”

Organizer Frog Gilmore described Bring Your Own Big Wheel as "not really a race more of an event."

To protect racers and spectators, parts of the street are lined with hay bales. Other parts of the street are lined as they regularly are with either concrete sidings or plants and bushes for a softer crash landing.

However the bales weren't enough to save racer Andrew Buchanan's costume. “I haven’t broken anything that won’t heal yet except the tutu. But this was a sacrificial tutu – I was kind of expecting it to go.”