By Steve Tawa

PHILADELPHIA (CBS) - While top professional teams are arriving in town for Sunday’s Philadelphia International Cycling Championship, amateur and recreational riders are gearing up to test themselves on the same course — for a cause.

Organizers say the Bicycling Open is a Gran Fondo, a big ride, not a race, from 7am to just before the pros take the course at 10:45 Sunday morning. Many have turned it into a fundraiser in collaboration with the event’s Charity of Choice program.

Executive Director Hunter Ziesing says about 500 people have signed up to ride, including those who just paid the standard entry fee of $95, and others who joined a fundraising team or started one of their own and listed their favorite charity.

“We’re just under $40,000 gross raised,” Ziesing says. “We’re hoping to get to $100,000 gross raised for the charities.”

Riders can opt for one, two or three laps on the 14.5 mile main circuit.

To accomodate the first Bicycling Open, the men’s pro race has been shortened by three big loops, so they will do 7 laps up the Manayunk Wall.