[Silver Birch Ar]

Arrow Speed and Speed Loss

How Do Manufacturers Rate Speed? IBO Speed Ratings are an industry standard of measurement used by all manufacturers. Speed ratings are based on a bow with a draw weight of 70# and a draw length of 30’’ using a five (5) grain per pound arrow (350 grain). Any deviation from these settings will cause a drop in arrow velocity.
Note: The chart below is a general guide for the amount of speed lost when accessories are added to your string.
STRING ACCESSORY SPEED LOSS ITEM SPEED LOSS
Brass Nock 2-4 fps
Peep Sight 3-6 fps
String Silencers 0-6 fps
E-Buttons 2 fps each
Rubber Peep Tube 6-10 fps
String Loop* 1-3 fps * Without brass nocks
VibraBlocks 0-2 fps
Speeds will vary depending on placement and manufacturer of string added accessories.
Speed loss of arrows over IBO standard of five (5) grains per pound (350 grains @ 70# draw weight):
Single Cam Every 3 grains of added arrow weight results in 1 fps speed loss. Example: 30 grains over IBO would result in 10 fps speed loss.
Dual Cam Every 2 grains of added arrow weight results in 1 fps speed loss.

 

[SHPoet]

Where did you get this info?

 

[pokem]

There are some good archery calculators available on the interweb you can use that show kinetic energy and momentum. You can use this to see where your bow starts to loose efficiency by adding tip weight in 10 to 25 gr. Increments. For a 65 to 70 pound dual cam it's around the 500 to 550 grain mark if I remember correctly. This doesn't mean that a 650 or 700 grain arrow will not penetrate better at hunting distances. Just gives you an idea of efficiency sweet spot of your bow.

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[SonnyThomas]

LIke SHpoet, where did you get your information? For one, some are moving to ATA for speed - specific weight, draw, draw weight and more. Even so companies still give speed as IBO. Hoyt example; 345 fps ATA.

Here's the plain and simple.
Speed adjustment rules of thumb;
2 fps / 1 # of draw weight
10 fps / 1” of draw length
1 fps / 3 grains of arrow weight
1 fps / 3 grains of weight on the string

 

[Kstigall]

You must account for the allowed deviations. If I remember correctly the draw length can be up to .5" long or maybe it's .25". At one time most manufacturers aggressively used the error margins to inflate their bows IBO rating. Now most, but not all, manufacturers advertise an IBO speed for bows that are reasonably attainable.

Keep in mind that if you have say a 26" draw you may not be able to subtract 40 fps from a bows rating and be close. If you are the shortest draw length for a particular cam you may see more than a 10 fps decrease for each inch of decreased draw length. It depends on the cam design.

 

[Silver Birch Ar]

A bunch of it is from bowtech. I have gleaned the other stuff over the years.

 

[Silver Birch Ar]

If you find an old bowtech owners manual, most of this is word for word.

 

[SonnyThomas]

I have a old 2005 Bowtech manual. Bought a Old Glory new - Black Marble, beautiful - mother to draw as Bowtech still had speed cams, not the "smoothy cam" that came out in 2006 - and wouldn't fit 2005 models. Does Bowtech still give the Birth Certificate? I have mine. Read some of what you have. That is Bowtech, not Hoyt, PSE, Pearson, Martin, Prime and so on............

 

[deadquiet]

Unrealistic speeds no one will ever see used to sell bows to the masses........lol. I guess if you have a 32 inch draw then maybe......maybe.

 

[Robspartacus]

From my understanding, ATA speed and IBO speed are two ways of measuring bow speed. The ATA is more strict and less fudge room. I know my last three models of Hoyt target bows were pretty much dead on. The ProForce, Prevail 37SVX, and the Invicta 37SVX have been spot on. None of these are "speed" bows but they have been plenty fast enough for paper and foam.

My Elite Victories and PSE Supras were also spot on. Actually, the Supra was slightly faster than IBO.

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[Silver Birch Ar]

This is great, thanks!

 

[Kstigall]

From my understanding, ATA speed and IBO speed are two ways of measuring bow speed. The ATA is more strict and less fudge room. I know my last three models of Hoyt target bows were pretty much dead on. The ProForce, Prevail 37SVX, and the Invicta 37SVX have been spot on. None of these are "speed" bows but they have been plenty fast enough for paper and foam.

My Elite Victories and PSE Supras were also spot on. Actually, the Supra was slightly faster than IBO.

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The last few years most of the PSE's that I am aware of have consistently been at the high end or higher than their published rating. Even with my nubby 26" draw the PerformX 3D and Xpedite meet or exceed their rating. I think what has really made the difference is that PSE has been accurately marking the draw lengths. For example, the PerformX 3D, Xpedite and Evoke 35 all had a draw length of 26" when the draw mod was set in the slot marked for 26". All too often to get a certain draw length you must set the bow at a mark that is published as .5" LESS than your desired draw length. PSE isn't "fudging" the draw length and the Evolve cams are very efficient.

 

[ronnielkier]

The last few years most of the PSE's that I am aware of have consistently been at the high end or higher than their published rating. Even with my nubby 26" draw the PerformX 3D and Xpedite meet or exceed their rating. I think what has really made the difference is that PSE has been accurately marking the draw lengths. For example, the PerformX 3D, Xpedite and Evoke 35 all had a draw length of 26" when the draw mod was set in the slot marked for 26". All too often to get a certain draw length you must set the bow at a mark that is published as .5" LESS than your desired draw length. PSE isn't "fudging" the draw length and the Evolve cams are very efficient.

This ^^^^^^^^^^^^^^^^ very true [emoji106][emoji106][emoji106][emoji106]

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