what determines how high or close the grips should be?
Its how comfy the reach is for you.
So is your ? what rise Ape hangers you should get?
I ask you this. How Tall are you?
Do you want your hands at shoulder level or above?
So let me put it to you this way. I'm 5'6. The most total rise I would go would be 12-14" apes. 14" max. I don't wanna be uncomfortable.
So then for me; I would do 2" risers and 12" apes for my height and taking into account the distance between the upper tree and the middle to the top of the tank. Pull back on the bars comes into play too.
So if your 5'8 or taller I would go 14" to 16" These numbers DONT include riser height.
Hope this helped.
OH BTW. Seat height will have an affect on the size of apes too. That is if you plan on lowering the rear only, than the rise of the apes will change too. Its like that on my bobber. My seat heat was 22" and I had 10" custom apes made for it. My back would hurt a bit because of where i wanted the bars placed for a compromise on appearance and comfort.
So I made my own spring solo seat. That raised me about 2" and now my reach is perfect. Again, I hope I'm not confusing you..lol