ADVISORY:  If you tighten the rear brake cable BEWARE:

IF YOU LOOSEN THE 5MM ALLEN SCREW BY ABOUT
TWO TWISTS TOO MANY THE REAR CLAMP NUT WILL
FALL OUT AND YOU WILL SPEND THE NEXT HOUR IN HELL
TRYING TO GET IT REASSEMBLED. BE CERTAIN TO LOOSEN
THE ALLEN SCREW BY ONLY  THE MINIMUM AMOUNT
NECESSARY IN WHICH TO PULL THE CABLE TO TIGHTEN IT.