if it ain't broke, fix it
Join Date: Nov 2008
Location: portland, the one on the left.
Bikes: bikes, a bunch.
Delver, lets talk about the crack, like ness said a long seat post and you'd be fine, but for peace of mind I'd fill the crack with some brass. I'd drill the ends of the crack too. Also cracks like that are an indication someone used the wrong size seat post and the over-tightened the seat pin to compensate, so make sure you have the correct size seat post, which can be a funky size on old schwinns.
I know it's not a high dollar bike but those old schwinns have character, something many bikes these days lack, and if it's otherwise in good shape, why not keep it in working order? another bike on the road is a good thing in my book. It's a 15 minute repair, which any bike shop could have done back in the 50's or 60's. now everything is disposable. No one cares to know what repairs can be safely done and what damage is irreparable . If you were in Portland Or I'd do it for you. Seat collar damage and stuck seat posts are the most common things I fix.