AMO vs IBO
06-20-2004 | 06:14 AM
#3
Giant Nontypical
Joined: Feb 2003
Posts: 9,175
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RE: AMO vs IBO
There are a lot of topics I wish the site administrators would put into a permanent archive, and this is one of 'em. The question comes up at least once every six months. Hint Hint, admin.[8D]
AMO has two standards, both are at 60 pounds draw weight and 30" draw length. The heavy arrow standard (the one most everyone knows and refers to) is a 540 grain arrow for 9 grains per pound. The light arrow standard (the one hardly anybody knows about, but has been on the books for 5 years now) is 360 gn arrow for 6 grains per pound.
"IBO speed" is usually advertised at 70 pounds draw weight, 30" draw length and 350 gn arrow for 5 gns per pound.
The main difference is the AMO spec is an actual specification standard listed with the American Society of Testing and Materials, ASTM 1544-99. That means any AMO speed you see advertised was taken with the bow set exactly at 60 pounds draw, an arrow at exactly 540 or 460 gns and drawn to exactly 30" - no matter where that 30" happened to occur in the bow's draw cycle.
The IBO speed though... It is NOT a specification but, instead, is a marketing ploy. The bow might be set at 70 pounds, but it could just as easily be set at 80. The arrow might be 350 gns, but it could just as easily be 300. The bow might be marked 30" draw, but actually peg the draw stops at 32". It is wide open for manufacturers to play games with, to advertise much higher speeds than their bows can actually deliver.
A few companies claim to treat the IBO thing as a true testing standard and adhere closely to it for their advertising. Very nice of them to do that, if they do, but they are not required to.
That's the difference between the two. AMO speeds are entirely reliable. IBO speeds have to be taken with a healthy dose of skepticism.
AMO has two standards, both are at 60 pounds draw weight and 30" draw length. The heavy arrow standard (the one most everyone knows and refers to) is a 540 grain arrow for 9 grains per pound. The light arrow standard (the one hardly anybody knows about, but has been on the books for 5 years now) is 360 gn arrow for 6 grains per pound.
"IBO speed" is usually advertised at 70 pounds draw weight, 30" draw length and 350 gn arrow for 5 gns per pound.
The main difference is the AMO spec is an actual specification standard listed with the American Society of Testing and Materials, ASTM 1544-99. That means any AMO speed you see advertised was taken with the bow set exactly at 60 pounds draw, an arrow at exactly 540 or 460 gns and drawn to exactly 30" - no matter where that 30" happened to occur in the bow's draw cycle.
The IBO speed though... It is NOT a specification but, instead, is a marketing ploy. The bow might be set at 70 pounds, but it could just as easily be set at 80. The arrow might be 350 gns, but it could just as easily be 300. The bow might be marked 30" draw, but actually peg the draw stops at 32". It is wide open for manufacturers to play games with, to advertise much higher speeds than their bows can actually deliver.
A few companies claim to treat the IBO thing as a true testing standard and adhere closely to it for their advertising. Very nice of them to do that, if they do, but they are not required to.
That's the difference between the two. AMO speeds are entirely reliable. IBO speeds have to be taken with a healthy dose of skepticism.
