Spine tolerance

[Michael Pfander]

I have been playing around with arrow tuning.  My question is simple, how much difference in draw length should a properly tuned arrow and bow combination accept before showing stiff or weak spine?  The reason I ask is that one of the guys I shoot with draws 2" more than I do and when he shoots my bow and arrows there is little or no change.  But when I work on odd positions they show stiff, meaning I am short drawing my setup.

Thanks
MAP

[s_mcflurry]

Looking at several arrow selection guides, it looks like there's a jump between spine every 5 pounds.  If I remember correctly, there's a 3 pound increase for every inch above 28 inches (should work to be about the same under 28 inches).

So, if my math is right, should work out to be a change in spine for every 1.6 inches.  Pure math, not sure how it works in real life.  :confused:

[McDave]

There seems to be a difference in how different people shoot a bow.  Two people can shoot the same bow at the same draw length and one will take a weaker arrow than the other.  Or, as in your case, two people can shoot the same bow at different draw lengths and both take the same spine.

I can't explain it, but I've heard it from enough places that I believe it's true.  Probably different releases and other subtle differences.  The bottom line is, you have to tune the arrow for yourself to get the best tune.