Quote Originally Posted by lauraelmore1033 View Post
They always offer them back, but I don't usually take them. I've already got a box of greasy metal bits and tires and tubes and other assorted bike junk just kicking around. What do you do with them?
Art is indeed one option.

The main purpose is to check how worn they are, and that way you know they're not passing them on to someone else (as I've seen done in some shoddy places). It can serve as an emergency part if needed in the future, too.