1 Boathouse Row (hut next to Lloyd Hall), 215/232-7900
You can rent hybrid and mountain bikes, child carriers, and inline skates from a Drive Sports 2 hut on Kelly Drive. It is located behind the Art Museum [1] near Lloyd Hall, the first large building at the start of Boathouse Row [2].
Hours are somewhat limited, but it is always open on weekends in summer. It’s wise to call ahead at all other times.
You can’t beat Drive Sports 2 for convenience if you’re staying in Center City and looking to get out on the Schuylkill River Bike Path.
Links:
[1] http://www.moon.com/destinations/philadelphia/sights/fairmount/philadelphia-museum-art
[2] http://www.moon.com/destinations/philadelphia/sights/fairmount-park/boathouse-row