I've got the same bike (an '02) and I took the freewheel off, I used it so seldom. I think that, once you get the hang of riding fixed, you'll find using the freewheel boring. You'll discover that you can climb any hill you'll find in Philly (I grew up in Bucks County) fixed. If you've got a 48 tooth chainring, you might want to consider a larger cog. You can save the 13 for race day.