Philly? So you're talking inner city "yutes".
No lawyer is going to be interested in this. Even if the cops could catch these punks, your chances of proving that they assaulted you are almost zero. Even if you could prove that they assaulted you, and they got convicted of assault, what could you get out of them? I'll bet you dollars to donuts, they live with mom, or grandma, in a project, or are section 8. This may surprise you, but lawyers are only interested in big fat paydays, not anything worthless like justice.
Since you were not seriously injured, the cops will not knock themselves out trying to find these people either. You should, however, report it to the cops nonetheless. I'm sure these twerps all got chubbies from attacking you. Since this brought them pleasure, I'm sure they'll repeat the same "game" with other cyclists. If the cops get 5 or 6 such complaints, they will probably act. They'll catch them by sending out a cop on a bike dressed in street clothes. These urban Einsteins will bash the cop and then all get sent to the pen for attempted murder of a police officer.
BTW, you do know that PA is "shall issue" state with regards to concealed weapons permits. Buy yourself a gun and learn how to use it. My friend who live in the Poconos never goes anywhere in PA unless he is strapped.