It started as a tweet from one of the world's greatest cyclists:
"Hey LA -- get out of your cars and get on your bikes. Time to ride. 7:30 tomorrow am. Griffith Park, LA Zoo parking lot. See you there."
The Twitter message from Lance Armstrong alerting L.A. to the pickup bike ride struck a chord with hard-core and amateur cyclists alike. Richard Ponce, 19, of Silver Lake was one of those who responded, calling friends to join.
"I've been following Lance Armstrong, and he's always been a hero to me," Ponce said Thursday, perched atop his yellow bicycle in the zoo's parking lot. "He comes to L.A., brings everybody together."
Hundreds turned out Thursday morning at Griffith Park to ride for an hour alongside the seven-time Tour de France winner. Some woke up early, driving from San Diego and elsewhere. Some were serious riders, others just fans.
Armstrong sent out a "good morning" tweet early Thursday, saying he was grabbing a quick coffee before heading to the park. When he arrived, he was quickly surrounded by news crews and fellow cyclists hoping for autographs and a handshake.
"It's mayhem; it's crazy," said Dave White, 27, of Burbank.
In a black shirt and yellow-streaked helmet, Armstrong led the group through three loops around a section of the park, seemingly riding hard and certainly riding fast. Not everyone knew what was happening. As the cyclists went by and photographers positioned themselves along the route, onlookers wondered about the commotion.
"Did you hear this? Lance Armstrong is coming by!" one woman told a friend as they stood near the Wilson-Harding Management Center.
It's not the first time Armstrong has announced a public ride via Twitter. In August, while in Ireland, he sent out a message saying that anyone who wanted to could join him for a ride in Dublin. More than 1,000 people reportedly showed up.
He sent a Twitter message before his scheduled trip to California challenging his fans: "And hey LA, we riding? Dublin set the bar pretty high . . . "
Armstrong's Twitter account shows he has nearly 2 million followers.
Some at Griffith Park said Armstrong's battle with testicular cancer had been an inspiration to them. Margaret McGlynn, 44, was one of those sporting a yellow Livestrong bracelet, which supports the cyclist's cancer research foundation. McGlynn, a triathlete, said several members of her family recently were diagnosed with cancer.
Armstrong said he enjoyed the hour-long event, joking that a couple of cyclists had given him a "hurt on the climb."
"It was good," he said. "Be back soon."
A little later, he sent out another tweet:
"Great ride in Griffith Park. Thanks, LA!" he wrote. ". . . Off to Montreal . . ."