HOW TO FIND THE RIGHT SPINE FOR YOU, the Spine Selection Charts are a great starting point, BUT it is only a reference point, not guaranteed to be an EXACT match for your bow.
STEP 1: Find your Arrow Length and Draw Length. The Correct Arrow Length is best determined by drawing back an extra-long arrow to full draw and having someone mark the arrow right in front of the handle. Measure the arrow from the mark to the valley of the nock groove. This is your DRAW Length. For ARROW length we recommend adding 1 to 2 inches to this measurement so that arrow point does not come off the inside of the bow shelf/ arrow rest.
STEP 2: Determining Actual Peak Bow Weight This is measured at your draw length, not by what the bow has written on it. The reason is a bow will be roughly 2-3# different for every inch ± the rated draw length. Even if you draw at your bow's rated draw (normally 28") the industry standard allows a bow manufacturer to be ±2# from rated bow weight and still mark/sell at the rated weight. So your marked 45# @ 28" bow could actually be 43-47# @ 28". Using an accurate scale, draw the string until you hit your draw length and hold. Observe the weight on the scale. Repeat as you see fit. Arrow Selection Chart Once you have your Arrow Length and Actual Bow Peak Weight, you are ready to select your correct arrow spine. Find your bow type and bow weight in the point weight you plan to use. Most common is 125 grains. Now move across the chart until you find your arrow length. Note: The 1/2" marks over lap on the chart, if you are on two different spines we highly recommend getting a test kit first. Remember, these are only recommendations, the final decision is up to you.