even with a 2" width at fades, i still find that ash can take a set,
glue in some reflex when you glue the backing on.
i usually go 2' wide fron fades to half way up the limb , then taper to 1/2" nocks- if you are putting tip overlays on, then you could go down to 3/8"- thats a std, "pattern" for white wood bows.
but like ryan said, maybe you want to go full width a bit further past 1/2 way, then taper to the tips.
g,luck
wayne