# Is "too much spine" a myth?



## toutfour (Mar 19, 2010)

Is "too much spine" with a compoound a myth?

I own a recurve and I understand the importance of spine with a non-center shot bow. 

The arrow flexes inwards as the string starts to move and, if of the correct stiffness and length, flexes outward at just the right time to avoid the riser.

****
If unfamiliar with this idea, go to youtube with:
Archers Paradox - Super slow motion video
minute 1:20 is a good shot


So with a recurve, if the arrow is too stiff, the arrow's oscillation is dampened and the fletching hits the riser.

My question:
How could it matter if an arrow is too stiff on a well-tuned center-shot compound bow?

Lots of postings say "the grouping will be poor". Some people say "too stiff" doesn't matter.
Can anyone explain why too much spine with a compound could be bad? . . . or are you all reading generic discussions of spine/stiffness and assuming it has to do with compounds too?


----------



## CardiacKid74 (Jan 18, 2005)

I have not noticed a big change in grouping when I change from a 100 grain to a 75 grain point. I would say a slightly stiff spine would be acceptable to most peoples shooting skills. If you need a 400 spine and your shooting a 300 spine thats a whole other story... But I have a bow that requires a 380 spine and use a 350 Victory with no issues..


----------



## sawdust2 (Jan 7, 2009)

*Spine*

The way I understand spine with a compound bow is that there are irregularities in the launch of the arrow even from a well tuned bow being shot with a release by an archer with good form. Absolute perfect doesn't exist. So, in effect a compound bow is inflicting bending forces on the arrow like the finger shot traditional bow but only to a much lesser degree and usually more in the vertical plane. This means that spine is still part of the equation for good consistent arrow flight from a compound bow.

As to a stiff or weak spine being easier to tune I subscribe to the slightly stiff being the easier of the two. I also believe that too stiff a spine will not absorb and then recover from launch irregularities consistently. Apparently I'm not the only one as the arrow manufactures all include charts recommending spine classes for given bow weights and arrow lengths. All of these charts are not identical for a given set of conditions but are quite similar.

Good luck.

sawdust2


----------



## 3children (Aug 10, 2008)

When was these charts done? What changed on the charts? What changed on the bows? Speed, cams, strings, center shot, just to name a few on the bow of today, yet the charts are the same ones I used in the 70's!! With the exception of the carbon arrow the charts all dictate the same spine. I myself with one of my bows at 55lbs can shoot a 300 spine arrow and 20-30yds cannot tell the difference. (maybe that is just a sign of how bad I shoot) At the 50+ distance with a .340 axis arrow I will group a bh right along my ft. I know the bow is tuned, and should be shooting the .400 spine and I have them also, but the op asked and this is what I found!! I know not all bows are equal in this for I tried with another bow and it was close, but I don't want to shoot "close" to the target!!


----------



## sawdust2 (Jan 7, 2009)

*So What Do You Recommend?*

Sounds like you are discrediting all the spine charts and suggesting that we shoot the stiffest shaft available. If it works for you that's just fine but I am going to stay with a "slightly stiff" spine for my bows. But then again I'm an avid paper tuner and I see the differences coming out of the bow as opposed to what happens 50 yards later. Granted, who cares how it launches as long as It hits in the right place but on that rare occasion when something isn't quite right you might consider spine.

Good luck.

sawdust2


----------



## CardiacKid74 (Jan 18, 2005)

Arrow company spine charts are useless in my book. They are a generic middle of the road map for guessing spine at best... I go back to my use of two bows to demonstrate how off an arrow chart can be. You have 2 bows set up the same. 70 Lbs and 30" with a 350 grain arrow. One is a PSE Deer Hunter and the other is a PSE Omen.

the PSE Deer hunter needs a .3925 spine arrow Victory V-Force 400 is needed

The PSE Omen needs a .2975 spine. Victory V-Force 300 is needed.

But the Victory arrow company arrow chart says both bows need the same 350 spine arrow just because they both are 70 Lb and 30" when in fact the chart would be wrong for both bows to have the correct spine..


----------



## sawdust2 (Jan 7, 2009)

*How About The Original Question?*

Would the 300 spine be "too much" in the Deer Hunter? 

sawdust2


----------



## CardiacKid74 (Jan 18, 2005)

Yeah. With spine the lower the number the stronger (stiffer) the shaft.. The Deer hunter needs a 400 spine where the Omen needs a 300 spine.


----------



## CardiacKid74 (Jan 18, 2005)

A 350 spine may be ok if you want to use a heavier head (125 grains or higher)


----------



## white.greg (Mar 15, 2007)

This is a great question, a bump to the top for that.

Unfortunately I can only speculate, just like everyone else here has. Maybe someone will post that really know something.

The one thing I do know is that the advent of a light, stiff, carbon arrow shaft, archers are able to achieve higher FOC%'s than the arrows of past. More forgiving with fixed blade broadheads.


----------



## TechStuf (Sep 27, 2012)

With a centershot bow and a whisker biscuit or drop away rest no arrow is too stiff. In fact, my results over the years indicate that the speed gained by a stiff shaft nearly compensates for it's increase in weight. What's not to love about GT Kinetics .200's that are skinny, thick walled, tough as nails arrows with service lives that only end when you lose 'em?

I've gotten my share of robin hoods with the old 2317's and 2419 aluminums back in the day, shooting from both an 80lb. Bear first strike compound and an ancient, Indian brand wood riser, plastic wheeled 50lb. compound that barely made center shot. Both with Golden Key two prong rests.

Unless you're shooting a stick bow that's not center shot, or any other bow with a fixed or finicky rest, shoot as stiff as you want. The more oscillation of an arrow in flight, the more wasted energy and lost speed potential.


Mitch


----------



## AUSSIEDUDE (Apr 17, 2009)

The optimum spine for any compound bow is .000 but unfortunately they haven't made an arrow that doesn't flex yet.

Spine charts have been around since the year dot and are great for giving you somewhere to start when tuning an arrow for a traditional bow. The spine is the most important feature when selecting an arrow for a traditional bow.

When compounds were introduced there was a lot of confusion about what spine was required for the higher performance that the compound provided. Many traditional shooters that never really understood why spine was important assumed that it would also be important with compounds. In reality there is no physical reason that an arrow needs to flex when shot through a compound bow.

Spine charts were adjusted for compounds with higher performance bows requiring stiffer shafts but this is a safety requirement and has nothing to do with a shooting requirement. Some charts even started listing an "optimum" spine for each bow depending on the performance, poundage and draw length and these charts were eventually transferred to computer programs. 

As more people became involved with the sport the belief that spine was important in compound bows spread like wildfire because to many if it is written it must be true.

Now that the tuning of a compound bow is being understood by more and more people (this is a relatively new technology) the spine myth is finally being exposed.

With a trad bow you tune the arrow to the bow. With a compound bow you tune the bow to the arrow.


----------



## Trapper13 (Jun 23, 2012)

I know this is an old thread but I'm in the market for some new arrows so I thought I'd ask which spine I should get in the gold tip hunters. I'm currently shooting maxima hunter 350's out of the bow in my signature. I'm shooting a 28" arrow at 70 lbs with a 125 grain broadhead. According to gold tip's chart if I read it right I should get 340's my question is how big of a difference would it make dropping down to the 300's. Also how big of difference would the .4 gpi in the 300 vs. the 340 make in my kinetic energy?


----------



## AUSSIEDUDE (Apr 17, 2009)

There would be nothing but benefits going to the 300's for hunting.


----------



## b0w_bender (Apr 30, 2006)

sawdust2 said:


> The way I understand spine with a compound bow is that there are irregularities in the launch of the arrow even from a well tuned bow being shot with a release by an archer with good form. Absolute perfect doesn't exist. So, in effect a compound bow is inflicting bending forces on the arrow like the finger shot traditional bow but only to a much lesser degree and usually more in the vertical plane. This means that spine is still part of the equation for good consistent arrow flight from a compound bow.
> 
> As to a stiff or weak spine being easier to tune I subscribe to the slightly stiff being the easier of the two. I also believe that too stiff a spine will not absorb and then recover from launch irregularities consistently. Apparently I'm not the only one as the arrow manufactures all include charts recommending spine classes for given bow weights and arrow lengths. All of these charts are not identical for a given set of conditions but are quite similar.
> 
> ...


Sawdust, you are spot on. The window for acceptable spine on a compound is a whole lot larger than that for a recurve or even a compound shot with fingers. The window is even larger with compound bows that have a really flat nock travel. Regardless of what others have said you will benefit by having the properly spined arrow. There will be an optimum spine and the closer you are to it the better the bow will preform.


----------

