Before I go on I'm not familiar with bicycle repair so I apologize if I can't explain things correctly. I have a Schwinn tourist with rear brakes that won't work. The front brakes seem to work fine to me, but what it looks like to me is that the wire connecting the rear brake handle and the brakes themselves is loose. What I've tried so far is unscrewing the brakes and placing them on both the lower and higher position option there are (they were originally in between the higher and lower hole), hoping that by doing this it would somehow tighten the wire, but it still won't do. Any suggestions? Thanks for your time.