Remember the SEPTA Strike in November 2005. Perfect Indian Summer weather, a bike parking station at the Municipal Services Building, and a commuter race in which the bicyclist lost to a speeding cab (at least it didn't cost him $12).
But it was also a time of gridlocked rush hour traffic and long cues of commuters waiting for trains with Tokyo subway like crowds.
You can relive the 2005 SEPTA and the 2006 NY MTA strike experiences by going to the Bike the Strike Blog.
If recent history repeats there won't be a SEPTA Strike in March, April or even May but just in case SEPTA has quickly put up a service interruption guide, which shows a lot of not so great Regional Rail options and nothing about bikes.