Sai gave this tip to me, having picked it up at Parmarth festival, from a very simple but fantastic teacher from Kerala, he told me. He said to do a perfect bow, you need to hold the ankles, then rock the chest up high. That gives you the lovely high lift that defines the bow. Then, move the legs away from the body! Normally, we draw it towards the back.. but this looks like fun. Somewhat like the crow, with your legs pressing into the shoulder .. seems difficult initially, but powers the pose by and by still you experience pure strength.