I tried the barrel adjusters today to address some of the derailleur problems I've been having. It worked, to a point.

For some reason, I now have a ton of slack in the front shifter cable (and therefore I can't shift into the middle or large chainring). I've tried loosening the bolt that holds the cable in place and manually pulling the cable taut, but there just isn't enough cable there. The same area of the cable (I marked it with a sharpie before I started) ends up at the screw every time. Yet there's still slack in the cable!

Any ideas?