weight tubes and arrow spine....

[Travisc406]

I bought two goldtip 3555 arrows to try out of my 53 pound bow. I put 5 inch shield cut right wing fletch on one and left the other bare. I am using 125 grain points and they are flying really well. I wanna bump the weight up with the 5 grains per inch weight tubes but am woundering how that will effect my spine. Any clues? thanx Travis  :confused:

[Mike Byrge@home]

I have found that adding the weight tubes makes the shaft act "weaker".

Mike

[hickry]

us too... i don't know why, but it was pretty evident when we did the bare shaft tuning...

[Rick McGowan]

I did lots of testing to make heavy shafts and I found that anything you add full length to the inside of the shaft, that dosn't have any spine of its own will weaken the dynamic spine of the shaft.

[Otto]

I agree and I believe it's because the mass has been added to the arrow and that additional mass causes the arrow to flex a bit more as the arrow oscillates in flight.  If I had to guess I'd estimate maybe a 3-5 lb change in spine.  I don't believe it's any more than that but it is noticable.