Spine selection for longer arrows?

Sorry, another arrow spine question....

If my "Correct Arrow Length" (Easton definition, length to rest + 1") is 27.75", but I'd prefer to shoot something an inch longer, where should I be looking on the charts?
The 28" column or the 29"?

I'm building myself up to buy my first set of ACCs and I'd like to get it right.

Thanks for your help.

Darron
 

mbaker74

Supporter
Supporter
When using hte charts with existing orrows, or different leangths to "correct", you look up the actual arrow length.
The spine alters wit hteh actual length of the arrow as a longer arrow has more distance to bend over, making it act softer. So, use teh actual length.
The "correct" length is only really a recommendation. Personally, my draw is not going to open out any more, so I have arrow length to position my clicker blade where I want it.
 

Rik

Supporter
Supporter
But basically, if you don't follow the recommendations, you're into "suck it and see" territory. The charts aren't designed for that.
 

mbaker74

Supporter
Supporter
But basically, if you don't follow the recommendations, you're into "suck it and see" territory. The charts aren't designed for that.
errrrr.... no.
If your measured draw length is 28", but you want to shoot a 31" arrow, theres no reason you cant, just look up 31" arrows at your draw weight on the chart and get them. The chart does not know the difference between your measured and actual length. Physics says how much an arrow of a particular length will bend with the same poundage behind it.....
 

4d4m

Member
So to summarise:

If you want to buy new arrows, use the "correct arrow length" for the charts.
If you want to see what group some existing arrows fall into, to see if they are (in theory) too weak or too stiff or just right, use the actual length.
If you want to see what some existing arrows would be if you cut them down, use the length you are considering cutting them to.

Would that be a fair assessment?
 

mbaker74

Supporter
Supporter
For new arrows, use "the correct arrow length" if you are happy with that length..... At the end of the day, if you arrow length is sufficent that you dont pull it off the rest at full draw, and not too long that you can use a clicker properly, then it doesnt matter..... Spine can be adjusted by trimming long arows down.....
 

Rik

Supporter
Supporter
errrrr.... no.
If your measured draw length is 28", but you want to shoot a 31" arrow, theres no reason you cant, just look up 31" arrows at your draw weight on the chart and get them. The chart does not know the difference between your measured and actual length. Physics says how much an arrow of a particular length will bend with the same poundage behind it.....
If the charts are made based on an arrow set up with particular contact points (rest, button), you can't count on it working with anything else. You *may* get close enough results by estimating that you can just plug in the longer length, but there are no guarantees. Yes the chart "knows" the difference between arrows which are 28 and 31 inches with the same draw length. Or rather it knows about an arrow with a 1 inch overhang, but not anything else with certainty (hence the specs).

They did work up software (several years back) which let you vary things like shaft overhang, but it was too much to maintain, given the amount of data gathering needed.

While we're on the subject, the amount of bend is not really the point. Spine is used as a proxy for determining how fast the shaft bends. When it bends as it moves forwards determines whether you have a match or not.
 
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