I used to rotate a lot, but now I hardly rotate at all. I think it just takes practice. My theory is that the rotation is due to not cocking the wheel far enough to one side quickly enough. I've observed a few of my friends learning how to trackstand, and they invariably don't turn the wheel sharp enough. This is because it's hard to turn the wheel sharply when simultaneously trying to slow to a stop. It's hard because you're trying to optimize three variables at once: wheel angle, forward velocity, and crank position. Therefore, the method that most people adopt is to make a sharp turn while slowing down; this will both slow one down and concurrently cock the wheel to one side. However, I believe this turning technique will result in the rotation you're talking about. I think the trick is to practice slowing to a stop in a straight line and immediately (as quickly as possible) cocking the wheel to one side (about 45 degrees from center). Keeping one's balance while cocking the wheel is key, and that's what takes practice. Once you get the timing right and you're able to end up in the correct crank position (i.e. cranks parallel to the ground), then you're set. I hope that helps...