Shuffle tracking is very similar to Ace Tracking. Both rely on the idea that cards will clump together during a shuffle.

Imagine that during a game you reach a positive card count. When your reach a positive count you know that there a more ace and ten cards in the shoe. You realize that this is the situation card counter look for.

Now imagine that the dealer has reached the penetration point in the shoe and shuffles before you can take advantage of the positive count. The shuffling process dictates that the dealer removes the unused cards from the shoe and place on top of the discard pile to begin the shuffle. You now know that a clump of ace or ten cards is at the top of the deck when shuffling begins.

You visually track the top of the deck through the shuffling process and determine where in the shoe the ace and ten card clump is. This requires you to be able to estimate a number of cards by simply looking at them. This skill requires practice judging the size of single decks. You will be able to judge a deck after some practice.

The dealer will then place the newly shuffled cards in the shoe. You know what deck of the 6 deck shoe contains the high cards. You adjust your bet higher when you reach that point in the shoe.

Alternatively, you track the clump just like Ace Tracking. Assuming the dealer scoops the face-up cards on the table to place them on the discard pile, you note the two cards going underneath a clump of ace or ten cards. When you see these two cards played, you know the high cards will follow.

That is basics of the shuffle tracking, to track a subset of cards through a multi-deck shoe during a shuffle.