There is plenty of on street parking for Bike Freedom Valley.
Registration is at Lloyd Hall behind the Philadelphia Museum of Art at Kelly Drive and Waterworks Drive. Across Kelly from Waterworks Dr is Sedgely Dr. You can park anywhere on Sedgeley. There are also several lots near the Lemon Hill Mansion. For Center City Parking information go to philapark.org
Of course you could come to Bike Freedom Valley via regional rail, subway or the PATCO High Speed Line. Bikes allowed on all lines all day on Sundays or put your bike on the front of a bus. When you get close you can bike to the start. This reduces your carbon footprint and saves your legs for a great ride.
If you need transit or trip planning info go to www.septa.com and ridepatco.org.