How does arrow weight affect speed

How much more speed will you gain with a lighter shaft? For every 5 grains of arrow weight reduction you will see roughly one fps increase in speed. There are practical limits to how light you can shoot. Going below 6 grains of arrow weight per pound of draw force is generally considered risky as your bow will be forced to absorb a lot more vibration.

Also, shooting fixed-blade broadheads accurately at speeds over to fps is very challenging. If you plan to take your speeds above this range you should consider mechanical heads or plan on spending a lot of time fine tuning your bow and shooting form. There is one rotational position for any cam at which the bow stores the maximum amount of energy.

In simple terms, your bow will be faster when the cam is rotated properly. You do this by adjusting string or harness length. If the cams of a two-cam bow are over-rotated rolling up too much string you can correct it most easily by putting twists in the string.

But remember, when you adjust string length you must then go back and reposition your nock set or string loop position and re-sight your bow. If the cams are under-rotated you have to twist the harnesses equally to keep the cams in time. After making this adjustment, be sure to go back and check your cam timing.

But, it is just as important if not more so with a single-cam as with a two-cam. Proper cam rotation will not only assure that the bow produces the optimum force vs. If the cam is under-rotated it needs to roll up more string put a few twists in the power cable. This is the cable that goes from the cam directly to the axle on the other limb tip.

Not the one that either attaches to the idler wheel or wraps around the idler wheel and then attaches to the bottom cam again.

If the cam is over-rotated which is the normal case put twists in the string equally on both sides. Make sure when choosing a new bow that it fits your draw length as described above exactly when the cam s are rotated to the optimum position. Your bow will perform better with the limbs bottomed. The amount of pre-stress on your limbs affects the shape of the draw-force curve and how much energy your bow stores when you draw it. When the limbs take on a greater bend at brace the bow comes up to poundage faster and stores more energy.

Your only recourse in controlling pre-stress is to shoot your bow with the draw weight adjustment bolts cranked down. You can back off a 70 pound bow or max out a 55 pound bow. The second option will produce a lot more speed for the same poundage.

The difference can be very substantial especially when you are dealing with a high-energy cam that is sensitive to pre-stress. String weight: Keep the string weight down to a minimum, especially at the center of the string. This can make several feet per second difference. Use a lightweight peep sight, reserve your string with a shorter section of serving and consider serving on your nock sets or using a string loop instead of heavier nock locating systems. The IBO method detailed in the arrow speed calculator instructions above sets up a bow and an arrow weighing 5 grains per lb.

Another common speed rating is the ATA rating, which uses a inch draw length, 70 lb. Thus, when a manufacturer touts its bow as having a speed of, say, fps, the truth is that a hunting weight arrow of grains from that same bow will initially leave the bow much slower — especially if the draw weight and draw length are significantly reduced.

In closing, using an arrow speed calculator will provide a solid estimate; however, you have to shoot your hunting weight arrow through a chronograph to know exactly how fast it is flying. And remember, in bowhunting speed is good — but it is far from everything.

My bow stayed the same: pounds at To make the change in arrow , I went back to our Arrow Efficiency Calculator. Knowing I shot my grain antelope arrow at FPS, I entered that data to find the most efficient arrow weight for my new whitetail arrow. However, we found the range is actually fps. Modifying the rule of thumb slightly to account for test results, we might say, "Expect to lose approximately fps of arrow speed for every inch you reduce your draw length on adult performance bows rated at fps and lower.

On similar bows rated over fps, the loss is closer to 10 to 12 fps. For every five grains of arrow weight added, you will lose Yup, that seems about right! Give a Gift Subscriber Services. See All Special Interest Magazines. All Petersen's Bowhunting subscribers now have digital access to their magazine content. This means you have the option to read your magazine on most popular phones and tablets.

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