It seems just as long as brace is always measured from the same point (no matter where that point is) and you find out what shoots best you are in business.
I can't remember where I got my information originally but as far back as I can remember the back of the rest has always been the point I used. The problem with this is when a you get a manufactures recommended brace height, you have to know where they measured from. This give me something to play with during the off season to see what height my bows like best....
Threaded Mode