The London Cycling Campaign is holding 'The Big Ride' later today.
They say it's the largest ever event in support of safer cycling in London, as they call on mayoral candidates to make the streets more inviting for cyclists.
As this promotional video shows, they point to Holland as a blueprint:
They are expecting thousands of Londoners on bicycles, foot, skates and rollerblades.
The event takes place just days before the mayoral election, and will follow a four-mile traffic-free route through central London; from Park Lane to Victoria Embankment.
More top news
CCTV and images show man suspected of trying to set the north London mosque alight in alleged Islamophobic hate crime
Detectives investigating a man's body washed up on the shores of the river have arrested a second man on suspicion of murder.
Keepers have the celebrating the arrival of the western lowland gorilla to 22-year-old mother Effie in captivity at the zoo.