Two St. Paul teenagers escaped a robbery attempt yesterday because the would-be-crook was overweight.   45 year old Bradley Schaefer approached the girls (ages 14 and 15) with a steak knife demanding their purses.  The girls took off running and outran the out of shape robber until they lost him.  Schaefer's being held in Ramsey County Jail on $70,000 bond.

(Getty Images)'s being held in Ramsey County Jail on $70,000 bond.