Incidentally my bamboo backed maple bow has taken 1.5 inches of set. It DOES have chrysals in one two inch wide spot on the lower limb where I got a bit too aggressive with a farriers rasp...My fault not the wood's as I was not paying attention to what side I used and gouged it badly. Easily fixed with a rawhide patch too. It is an inch and half wide at the fades but the bamboo is only an inch and an eighth wide on the back (narrower as suggested in the chapter on design and performance in the fourth installment of the TBB)I am not trying to debate whether it can or cannot be done. That argument is tired and already I know it can be done by...I would like to encourage experimenting on razorbacks part. So please take this for what its worth which is probably not much. Personally if I was to build a birch bow I would follow comstocks advice and back it with rawhide.