The band of active and retired firefighters took off on their bicycles from the Santa Monica Pier for the more than 3,000-mile trek that will take them through 14 states over the course of 40 days.
"Something like this is a little bit of a bucket list, to travel across the country. But, for me, it was a little more personal because I lost some friends back in New York," said retired L.A. County firefighter Buck Buchanan.
Buchanan, who is leading the group, will carry the pictures of some of the victims, including the pilot of Flight 77 and the friends he lost when the Twin Towers fell. He says those photos will help him push through the physically and mentally challenging parts of the ride.
"For us, it's not a race, it's an event," Buchanan said. "We're here to remember those that we lost and to raise money for the charities that we support."
The cyclists are part of the non-profit group Fire Velo, which raises money for firefighter cancer awareness, mental health and wounded veterans.
The group received a hero's send off, with fellow firefighters, family and friends cheering them on. During their travels, they'll stop and visit memorials dedicated to the victims of 9/11.
"We are going to be stopping in Shanksville, Pennsylvania where Flight 93 crashed. Then we are going to stop at the Pentagon, then we are going to the memorial in New York," said retired firefighter Marv Williams.