In the following clip at 0.30 and 0.40, you can see that you will sweep your opponent's leading leg when he tries to move his leading leg closer to his back leg. This is the simple principle that if your opponent wants to reduce his base area (defined by his feet), you will help him to reduce it even more.
http://www.youtube.com/watch?v=mUnkPZSgHCY
My concern is when your back foot, front foot, and your opponent are on a straight line, if you want to move into his side door, will you move your front foot first or will you move your back foot first?
I believe Bagua guys will move their front foot first. This will cause 'legs crossing" which will give your opponent an opportunity to sweep you.
Here is the difference.
- If you move your back foot first, the distance between you and your opponent has not been changed. If your opponent's can't reach you before, he still can't reach you now. So when you move your back foot first, you have not committed yourself on anything. You don't have to take any risk.
- This is not the case when your move your front foot first. The moment that you move your front foot, the distance between you and your opponent has been changes. Your opponent may not be able to reach you before, he may be able to reach you now. So when you move your front foot, you have committed yourself right at that moment. You have to take the risk to be swept.
Do you want to give your opponent a chance to attack you while you can't attack him (when you move your front foot first)? Or do you want to give yourself a chance to attack your opponent, at the same time that you don't create any chance for him to attack you (when you move your back foot first)?
I like to align my back foot, my opponent's front foot, and his back foot in a straight line when I attack. This way, no matter how my opponent may move his leading foot, his leading leg will always be under my attacking range. In order to do so, I always have to move my back foot first (to do the alignment). If I cross train the Bagua system, the basic Bagua footwork will contradict against my bread and butter footwork. I don't see any reason for me to do that.