I do know that the tension properties of the sapwood are pretty good. I have made some pretty hard working limb osage bows with sapwood backs and haven't had a tension failure, and it is plenty good in that respect. The wood closest to the pith does seem to be darker and more dense though, (and I would just assume from knowing that, that it would be stronger in compression), so I would agree with george that it is not the best scenario. But I would still think a sapwood backed heartwood bellied osage bow would be on top of most other bow woods in compression strength? The one thing that would change my thinking is something that has never really been talked about, which is if the back itself takes set, or "stretch" might be a better word, and not stretch back to the former dimensions/length, than could that cause a bow to have set, even though it is obviously less likely or causative than the belly being crushed? Or might it be a factor to consider at least? I don't know but if I had to guess I would definitely think osage heartwood would have a higher resiliency than osage sapwood.
