You can use a 4 inches pipe (foam roller type), to start getting some of arch and the increase it to 6 inches (after sometime). Not sure how is your set up but try to start getting like 6 inches pass the bar. Get your feet tight first and then push your head back down w/o moving your feet from last position. Made sure that your groove is not 100% straight up but more like in an angle toward your eyes.
*The 6 inches is not a science. Is more like my own distance. We are not too tall...Distance and space will change with time depending on flexibility...
Last edited by 1morerep; 10-03-2013 at 03:56 PM.