Core apples, then peel the skins. Use a mandolin to slice thin (the thickness is up to you, the thinner they are the crispier they will be and less time it will take).
Mix your cinnamon and sugar in a bowl. Add half into a gallon baggie with half of your sliced apples and shake until fruit is coated well.
Separate apples and lay flat in one layer on stainless steel rack. When that is full slide it into your dehydrator.
Use another rack to lay out rest of fruit.
Then add the remaining cinnamon and sugar mix into your baggie with remaining sliced apples and shake again.
Lay remaining apple slices on trays until they're full. Close door and set dehydrator to 145 degrees for 6 hours.
Timing will vary slightly depending on how crisp or chewy you like your apples, and how thin you sliced them. Check at 5 hours and see what your thoughts are, keep in for longer to crisp up more.