Neighborhood Bike Works

Neighborhood Bike Works is a non-profit youth program. You can come to Neighborhood Bike Works to work on your own bike Tuesday, Thursday and Sunday from 6:30-9:00, or Wednesday (same time) for women and transpeople only. Used bikes and parts that are surplus to the needs of the youth program are made available for a donation. The time that adults can come to the shop is known as "Bike Church" and is operated mostly by volunteers. NBW also offers classes on bike repair for adults on Monday Nights

Pros: Free service to the community.
Things that are available are cheap
Supports a deserving non-profit when you donate or buy stuff
You can work on your own bike and learn as you go from skilled facilitators

Cons: often crowded, you have to queue to get in often,
that they don't sell the best bikes they have
no accessories or new items for sale.
Not open very often
Is not really a bike shop. They don't sell new stuff or fix your bike for you. If you want that, go to some of the many fine actual bike shops in Philadelphia.