Beadman, I wish I could give you a better answer. But I don't really measure for spec's like that, the only spine testing I do is by hand. I compensate for the lack of uniformity by making my arrows a little bit longer than usual, I have found longer arrows fly better. I have learned that, to get the same stiffness as cane or hardwood, the rose shafts do need to be a little thicker. The shoots have a lot of "pith" in the center, so they tend to be a bit weaker. My bow is 50#, and they shoot fine out of it. Here is a picture of the middle of one of the shafts compared to one of my hardwood shafts. The rose (top) is only slightly thicker. One more thing, rose also has alot of charachter in it,it won't look quite as pretty, but it will still fly good. Hope this helps