Deflection VS Spine.

[capt eddie]

Somewhere along the way I missed the memo to change from spine weight to deflection. As I am looking into carbon shafts I will see that a shaft might be spined one weight with a certain deflection,  And another shaft will have the same deflection but another differant spine weight.  I see carbons listed as 300,400, 500 deflection.  Are these certain spine weights?  What is the standard deflectiond are set at?28inches??? Where can I be brought up to speed on this deflection thing?

[freeman]

Eddie, when it comes to carbons it's kind of a mess. Don't pay any attention to the poundages marked on the shafts. And the deflection is measured differently for some reason. .500 spine on my tester is like #52. Take a .500 carbon and it spines around 66#. WHY?  who's brilliance was it to change the way in which spine is measured? I thought there was already a standardized system in place?

[Bill Carlsen]

Everything changed when compounds arrived on the scene....and I believe the change agent was Easton.

[sffar]

I have one of the Ace wall mounted spine testers–nothing fancy. I find 340 carbons test at about 90# and 500's at about 65#. The tester has two indexes, and the "500" arrows read about 400, while the "340's" spine about 280. This with 3 Rivers Trad Only 340's and Easton Flatline 500's. ICS Bowhunter 340's also spine about 90#. Very strange "system."

[metsastaja]

Stu's calculator  http://www.heilakka.com/stumiller/
has a static spine converter for both amo ans astm

AMO is 2# at 26 while ASTM is 1.94# at 28.