I use hickory (with most all hard woods. ) for the backing. I use bamboo and all other woods as a backing, I use Hard Maple for backing for all woods, I use walnut for backing with all, except osage. I have found only osage and bamboo work the best. But I think you might be able to use maple or hickory.The problem is osage tends to over power other woods in my opinion.I have found white oak to be a backing material also if cut properly.I consider ash a good bow wood ,but needs backed . However I have made english bows all ash d- shape with no backing.Most board bows need backed as the growth ring has been violated. So unless you choose, cut the board , you back the bow or are at the mercy of nature. Hope this helps, Again this is some of my experiences only. Denny