The first "ghost bikes" were created in St. Louis, Missouri in 2003.
Since then, they've appeared in more than 200 locations around the world.
Ghost bikes are roadside memorials, "stripped of most of their parts, painted white, and placed at locations where cyclists are killed, usually by motorists," says ghost bike volunteer Danny Gamboa. The memorials are also meant to serve as a reminder to drivers, he says.
"Not a lot of people know that a lot of cyclists are losing their lives on our streets, so we want to raise that awareness and we want that ghost bike to be a catalyst for change in everybody's community," says Gamboa.