Sounds like the weather is going to cooperate this weekend for riding There are LBS that rent bikes. I would highly recommend that. Also there's always Reading Market downtown which is fun and yummy :-) The SEPTA day pass will get you just about anywhere you want to go for $11. I will be stuck in my apartment studying for final exams. Wissahickon Park is a great place to go walking, running or mountain biking (pretty intense though if you go on actual MB trails). You can always grab your bike and Cyclocross it up the museum steps and pretend your in Rocky! If you are downtown there are TONS of rides leaving out of the art museum area over the weekend. Go to Bicycle Club of Philadelphia or Suburban Cyclists United to find rides all over the area.