The specific spine of the arrow has nothing to with the dynamic spine of the arrow, it is merely a referance for typing different shafts.

Like BG said, your arrow can be any length as long as it spines well for the bow. I have shot from 21 to 29 inch arrows out of my bow. Providing they were the correct spine they all shot well.

Normally though you want an arrow that is about the same as your draw length. AMO standards are 3/4 of an inch less than your draw length. This is the length the arrow charts and online calculators go by. Since they base draw length off the arrow length you give them you need to give the proper the arrow length. If you are shooting a longer or shorter arrow than you need the charts will assume you have a longer or shorter draw length as well.

This is where some of the newer software comes in handy because you can tell it your actual draw length and check spine for different length arrows. As in my case, I have a 26 inch draw and shoot 27 inch arrows. That is long for me, but I calculated in the difference and have the proper spined arrows at that length.

Contrary to what people will tell you, arrow length has no great effect on accuracy or flight as long as it spines correctly for your bow. The only downside would be shooting a very short arrow with an overdraw. The arrow will still fly well with adequate fletching, but the overdraw is a bit tricky to shoot well unless you have perfect form. So your accuracy could suffer from that, but that is not really the arrows fault. You would have the same problem with a longer arrow and the same overdraw. It is a set up issue, not an arrow length issue.

The only thing shooting a longer arrow that is properly spined for you bow will do is cause you to shoot a heavier arrow than is needed. For some I don't think this is all bad.

Paul