## What is arrow spine deflection?

Arrow spine is a measure of stiffness which is gauged by how much the arrow flexes when weight is applied. Arrow spine is rated by “deflection”, which is a measurement of the shaft’s propensity to bend when force is applied.

How do you calculate arrow spine?

Static spine is how much an arrow reacts when a 1.94 lb. weight is hung from the center of the arrow. To calculate this, arrows must be 29” long and supported at two points 28” apart. The number of inches the arrow bends multiplied by 1,000 is the arrow’s spine.

What should my arrow spine be?

Adding weight to the front of the arrow weakens its spine. That’s why Gold Tip recommends a 400 spine for a 27-inch arrow with a 100-grain point shot from a 60-pound bow, but also recommends a 340-spine arrow if its length and draw weight stay the same, but its point weighs 150 grains.

### Are arrow spine charts accurate?

As for the arrow charts, I have found them to be vastly inaccurate. Not really even a good starting point. In my experience, the Gold Tip chart would have over-spined my long bow by one, and in some cases, two spine classes.

What does GPI mean on an arrow?

grains per inch
The industry standard measurement for weight is grains per inch (GPI). (One grain = 1/7000 of one pound). There are many factors that make up GPI including: arrow diameter, wall thickness, and shaft material. The GPI weight of listed arrows does not include the weight of the point, nock, insert or fletchings.

What happens if arrow spine is too stiff?

If the arrow’s spine is too weak or too stiff, the arrow will not correct itself as soon as it should while in flight. If that arrow is weak and continues to flex (has a low spine rating), it’s going to veer off target. Likewise, if the arrow is unforgivingly stiff, it also won’t follow the path the archer intends.

#### What does 340 mean on arrows?

As with combination arrows, a smaller number means the arrow has a stiffer spine. Therefore, a value of 340 indicates a stiffer and heavier spine while a value of 500 indicates the lightest and most flexible spine.

What does 45 60 Mean on an arrow?

it means 45-60 lb bow.. If your draw is longer than normal and you shoot 60 lb you usually need a lttle more that what the arrow is rated for..

What does 2219 mean on an arrow?

The first two digits stand for the arrow outside diameter (OD) in 64’s of an inch. The second two numbers stand for the wall thickness (WT) in 1000’s of an inch. So for the aluminum 2219 in my case, the OD is 22/64″ or 0.34375″ and the WT is 19/1000″ or 0.019″.

## What happens if you over spine an arrow?

Spine strength must be matched to bow draw weight. If your arrows are too lightly or heavily spined for your bow, the “archer’s paradox” movements will be extreme, resulting in poor arrow flight and loss of accuracy. (It’s better to err on the stiff, or too heavily spined, side.)

How is the spine of an arrow measured?

It’s measured by applying an 880-gram weight to the arrow, suspended from the center of the shaft. The arrow must be 28” in length and supported at each end of the arrow. Spine is measured by the number of inches a shaft deflects (bends) X 1000. For example, a 500 spine arrow bends.5 inches when the weight is applied.

Which is the best chart for Arrow deflection?

But other arrow manufacturers offer a more simplified chart with an arbitrary number system, like the sample chart on the right which just references draw weight and arrow length. If you go by the simple chart method, then you’ll need to apply a little common sense – particularly if your bow setup isn’t exactly ‘average’.

### What is the deflection of a carbon Arrow?

Easton’s familiar carbon arrow spine sizing system (500, 400, 340, 300) is basically the arrow’s spine deflection x1000. So a 500 shaft is a .500″ deflection. A 340 Easton shaft is a .340″ deflection and so on. So forgiving the shift of the decimal, the Easton spine sizing system matches up nicely with actual spine deflections.

Which is stiffer a 500 spine arrow or 330 spine Arrow?

The same Easton arrow comes in a variety of stiffness: the lower the number, the stiffer the arrow. For example, a 330 arrow is stiffer than a 500 spine arrow. There are two kinds of spine (stick with us, we promise not to get too technical).