Two such participants were Medford cyclists Brandon Beringer and Kendyl Cocco, both 17-year-old seniors at Shawnee High School.
They ride their bikes around their New Jersey neighborhood, and neither was bothered by the rain.
"The rain was fun," a smiling Beringer said after finishing the ride.
"It's better than being hot," Cocco quipped.
Rachel Slotcavage, 28, a surgery resident at Cooper University Hospital in Camden, and her fiance, Neil Masangkay, 27, a neurologist at the Hospital of the University of Pennsylvania, have ridden in the event before.
"This is my second time," Slotcavage said. "A little thing like the weather isn't going to stop me."
She used to commute to work on her bicycle from the couple's home near Graduate Hospital, but getting over the Ben Franklin Bridge is a little intimidating, she said.
The rain did cause some problems for riders.
Mike Ruddy, 39, of Folsom, stood under a sycamore with his shivering children at the end of the seven-mile route, which took them through Center City and back to the Art Museum.
Still, he said, "It's a cool ride. I would definitely do it again."
Dan Seyfried, 42, traveled to the city from the Lehigh Valley with son Noah, 2, for the ride.
"We could have kept on going, but he was tired," he said of Noah, who appeared to be on the verge of a nap in his bicycle seat.
Maggie Dahl, 63, and husband Michael Long, 60, of Arlington, Va., decided not to ride but stood near the Parkway to cheer riders on.
Kicking off the event was Mayor Nutter, who wore a red windbreaker, bike shorts, and a helmet.
"We're trying to make Philadelphia the most bike-friendly city in the country," he said to the cheers of bicyclists as they prepared for their rides.
