chased mine down to roughly 1\4 inch because i wanted mostly heartwood aswell. I nearly chased it to 1 ring and blew it at the end, violating a ring, but i tillered and shot the bow numerous times without backing and itshot great. I later decided to back it with sinew just to be safe.....but i dont think it needed it, next time I am really going to go for 1 ring all the way..incredibly tough to do on cedar, but I nearly did it and I will do it next time. I wont back it next time either. I want to see how unbacked cedar with 1 ring backe can hold up long term. but here is the one I built this past month btw its from a sapling so the heartwood core is radiused and so it looks like there is way more than 1\4" of sapwood.