yes, it's called free ride. www.freeridepgh.org
we have limited hours over the winter, but we'll be open saturdays from 1-5pm. if you have bikes or parts you'd like to donate, just come in with them and someone will help you.
if saturday doesn't work for you, you can donate whenever construction junction (the building free ride is located inside) is open.. just ask an employee how to do this.