When Jake O'Neill first tried to stop London knife crime by getting teenagers on their bikes, "20 to 30 people" showed up.
On Saturday, 3,000 people - mostly teenage boys - rode through the capital, pulling tricks and stopping the traffic.
Jake, 19 - also known as Jake 100 - set up the Bikestormz project with his friend Mac after his best friend's older brother was stabbed to death.
"I quite literally want people to put their knives down and pick their bikes up," Jake told the BBC.
"Hence the slogan Knives Down, Bikes Up."
Jake is from east London, where "some of his friends" were stabbed.
"It really made me think about what I could do to change things in my community," he says.
"We wanted to bring young people together, take them off the streets and give them something uplifting to do."
He thinks riding together makes violence less likely. "They've never been in a fight whilst riding their bikes," he says.
But not everyone was as positive. One local resident said the cyclists "had no concern for their own safety."
"Hundreds of young people were cycling down Battersea Park Road," she said. "Some were doing wheelies and standing on their bikes whilst moving."
One eyewitness said he was walking to a bus stop by Battersea Park when he saw the group come round the corner on their bikes.
"On three instances I saw cars swerve to avoid a full on crash," he said. "It was total chaos."
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Jake admits it "is a bit dangerous".
"But the buses don't move," he says. "The local police support us and they cordon off the areas. Only the odd car driver beeps at us."
Clarence Watts, who lives in Southwark with his mum, was one of the bikers at the ride on Saturday. He describes it as "life-changing".
"It was amazing to see people riding together in support of such a great cause," he says. "We rode together as a family."
His mother, Patrina Watts, was also there: "I was there to show my support for my son and all riders," she says.
She called Mac, one of the project's founders alongside Jake, a "role model for the youth around London".
Jake says everyone is welcome to join them on their rides - and no prior experience is necessary.
There are two London Bikestormz events a year, he says. And there are rides all over the UK which have been inspired by Bikestormz.
"People come and they don't know how to do any tricks but they have a great time," he says.
"As soon as you start slapping rules on kids they aren't interested. So this allows kids some freedom in a very positive way.
"I feel proud of everyone for coming on Saturday."
By Victoria Park, UGC & Social News