So what IS the effect of arrow stiffness ?

BOETJE

Supporter
Supporter
Greetings ,

Been trying to read everything on spine stiffness for recurve archery.
Everything about bare shaft tests, where they land , when they are too stiff or too weak, poundage,
the Easton arrow charts and so on.
I have tried the bare shaft tests , and tried two grade weaker spines , but to be honest
even the weaker ones landed to the left, when unfletched. Which leads me to think that you
have to be a pretty good shot, with good technique , to be able to make some valuable conclusions.
Which leads me to the main question :
How does an "incorrect spine" manifests itself.
Is it mainly the grouping that goes to pot : will you never be able to get a good grouping if your
arrows are one stiffness grade out from what it should be, ?
Or is it just another fine tuning aspect , that only really good archers will notice , and relative novices barely ?
Would the correct arrow spine all of a sudden reduce your grouping from 15 inches to 5 inches at 60 meters ?
 

Rik

Supporter
Supporter
Okay, some basics...
"match" is to do with how the shaft clears the bow, not grouping as such.
If you've been looking, you will have seen the diagrams and high speed film footage of how that happens and how the shaft bends first in towards the handle, then away.

"stiffness" is a proxy measure for that bending frequency. "stiffer" = bends quicker.
But it only works within a design of shaft, so comparing shafts of different designs can result in getting a different spine match.

So with matching an arrow you're attempting to get a shaft that puts that second bend as cleanly around the handle as you can - reduces the chance of contact when your variations (and mistakes) are added into the equation.

So in that context, you can see that a poor match is likely to dramatically mess up grouping. A good match is not a guarantee of good grouping (you can always screw up enough to negate it, or have something in your setup which will interfere).
It also becomes apparent why going stiffer than the absolute good match is often not a problem - the shaft is bending less, which can help clearance, or be adjusted for to avoid resulting problems.

Tuning is something separate from this, and is more to do with tweaking things to fit you. The reason you have to be quite good to do it successfully, is that otherwise you're likely to be varying and drifting in your execution enough that the tweaks you do in one session won't be correct for the next one... Ever seen people who seem to be constantly tuning?
 

4d4m

Active member
Excellent, thanks Rik! The best, most concise and understandable explanation of spine and tuning I've read in 4 years of archery.
I'm going to nick that for our club's Facebook group if you don't mind. :)
 

BOETJE

Supporter
Supporter
So : if you would have an infinitely stiff shaft , each archer , regardless of poundage would be able to use it ?
Providing it wouldn't look like a telegraph pole...
The trick is to find the lightest smallest arrow ( for flying far and fast ) , that won't slap against the riser ?
 

Rik

Supporter
Supporter
Depending on the handle/bow, that could be true. It certainly appears to be the case (so far as I understand it) that you can't go too stiff on a well set up compound. (Now just wait for a compound expert to shoot that speculation down :) ).
But for a recurve you have to consider that even if the shaft does not bend, the string string still follows a curve, and if the shaft doesn't bend enough, there may be contact because of the angle the string drags the shaft to, pivoting around the contact point...

(though if you're going to talk about infinitely stiff arrow shafts, I might have some cubical cows I can sell you... ;) )
 
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