For those that are new to archery, many of the numbers and specifications that pertain to a bow can be quite confusing. This is understandable, as it is not always made clear as to just what these numbers represent, and many questions often arise. One such question that is often asked is what is IBO speed.
IBO speed is characterized as the speed at which an arrow with a weight of 5 grains per pound of draw weight is fired from a given bow.
There is no specified draw length included in IBO testing, and while the bulk of manufacturers conduct testing at 70 pounds of draw weight, weights of up to 80 pounds can be used as long as arrow weight is adjusted accordingly.
What’s Your Bow’s Real Speed
It is of immense value to understand what arrow speed ratings associated with a particular bow are telling you, as the consumer. These numbers can often be misleading if you are not aware of what exactly it is that they refer to.
Point Blank Speed
When a FPS (Feet Per-Second) rating is given regarding a particular bow, this speed is gauged at point-blank range. This is dictated by the measurement that is received by a chronograph positioned directly in front of an archer’s arrow.
As the arrow is released, this chronograph reads and displays the detected arrow speed in a FPS measurement.
It is of value to understand that these speeds fall drastically as an arrow travels further downrange.
Therefore, such a figure is seldom accurate in predicting downrange performance, as several factors play upon arrow velocity with every successive foot that is traveled.
Which Factors Impact Arrow Speed?
Several factors have a direct bearing on the speed at which an arrow travels. Because these factors vary from one archer’s set up to the next, the only true gauge of your bow’s real arrow speed is taken with the assistance of a chronograph as it relates to your bow.
A bow’s draw weight factors heavily into the speed at which an arrow is propelled downrange. The higher the draw weight of a particular bow, the greater the kinetic energy imparted upon the arrow becomes.
This, in turn, yields faster arrow speeds. In fact, for every 10-pound increase in draw weight, arrow speed increases an average of 20 FPS.
The length at which your draw length is set, also is reflected heavily by your arrow’s speed.
The longer your draw length is, the longer an arrow remains in contact with the bowstring during the shot cycle, and the more kinetic energy is transferred to your arrow upon release.
This means that an individual who shoots a longer draw length will naturally observe higher arrow speeds.
As a general rule, for every additional inch of draw length, a gain of approximately 10-15 FPS of arrow speed is to be expected.
As arrow weights fluctuate from one application to the next, so do arrow speeds. A larger projectile naturally flies at a slower speed than that of a smaller size.
For every additional 5 grains of arrow weight, arrow speed is reduced by an average value of 2 FPS.
Although this does not seem like much of a fluctuation in speed, arrow weights can vary as much as 100 grains, or more between applications. This can lead to sizable changes in arrow velocity.
String Mounted Accessories
It is of value to understand that the bulk of bow manufacturers’ speed ratings are measured from a bow that is absent of all accessories. When a bow is purchased, it is set up for its owner with string-mounted items such as a D-loop, peep sight, and sting silencers.
The addition of these accessories alone can lead to a reduction in arrow speed of up to 10 FPS.
What Is IBO Speed?
In the years since the advent of the compound bow, manufacturers have strived to outdo one another in the arena of speed. This race toward ever-increasing arrow velocity led many to begin questioning the validity of manufacturers’ claims toward their bows’ arrow speeds.
Because of this, the idea of a governing body, or standard metric to guide manufacturer speed testing grew in popularity.
This intuition led to the birth of multiple standards from which arrow speeds were to be measured. One such standard is that of IBO testing.
Who Invented IBO Speed Specifications?
The IBO speed specification was invented by the International Bowhunting Organization. This organization has long been an advocate for bowhunting education, safety, and recruitment.
The International Bowhunting Organization’s motto is, “To Promote, Encourage, and Foster the Sport of Bowhunting.”
What Does It Stand For?
IBO Speed specifications are intended to standardize the method that is used to determine bow speeds across the industry. This assists in preventing false and inflated claims of a bow’s speed that might confuse consumers.
What Is ATA Speed?
ATA Speed is yet another standard for determining and recording speeds of bows across a wide range of manufacturers. This unit of testing assists in adequately describing a bow’s capability to consumers.
This standard is based upon the criteria of a bow featuring a 70-pound draw weight (+/-.2), with a 30” draw length, shooting a 350-grain arrow.
This standard is the formal specification cited by both Hoyt and Darton archery in the marketing of all of their bows.
Who Invented ATA Speed Specifications?
ATA stands for Archery Trade Association. The Archery Trade Association is an organization that aims to further strengthen all aspects of archery as a whole, as well as the manufacturing, supply, and distribution chains from which modern industry practices are derived.
What Does It Stand For?
The ATA specification was established in an attempt to further standardize bow speed designations on an industry-wide scale.
Because this metric relies heavily upon a set draw weight, draw length, and arrow weight, ratings of this nature tend to be a more reliable representation of actual bow speeds based upon the criteria set forth.
Which Metric Is Best For Buying A Bow?
While IBO Speed is still commonly used by manufacturers to specify the speeds of their bows, the ATA standard tends to carry more weight in an apple-to-apple style comparison.
Since IBO testing features several variables in regards to draw length and maximum draw weight, many such ratings far exceed the speeds that are viable of a fully outfitted bow under normal circumstances.
On the contrary, ATA testing relies solely upon the criteria that have been set forth for testing purposes.
This eliminates any opportunity for manufacturers to artificially inflate their values, thus misrepresenting their product.
How Does This Correlate To Success In The Field?
When attempting to decipher if a chosen bow/arrow combination is adequate for the hunting of a particular game species, one must take into consideration the amount of kinetic energy that is delivered downrange.
Kinetic energy is the value of force that is imparted upon your target with the delivery of an arrow and directly dictates the amount of penetration that can be expected.
The following formula can be used to figure the kinetic energy of an arrow fired from an individual’s specific bow/arrow combination:
Fps² x Weight of Arrow/450,240 =Arrow’s Kinetic Energy
For more information on finding the kinetic energy of an arrow, watch this video.
- Big Game– The vast majority of today’s compound bows are more than adequate for the taking of big game species. As long as a moderate draw weight and length are utilized, you should have no problem obtaining the minimum kinetic energy needed for a clean kill (45 ft-lbs or greater).
If in doubt, use the above-mentioned formula to assess the kinetic energy produced by your bow/arrow combination.
- Small Game– Virtually any bow is well suited to the taking of small game. Very little arrow speed or kinetic energy is required to achieve ample penetration for a clean, quick, and ethical kill.
IBO Speed And The Role It Plays
With the abundant number of compound bows on the market today, it can often be difficult to grasp how best to compare one offering to the next. IBO Speed is one of the many figures that is used to compare compound bow performance.
Care should be taken, however, as these numbers cannot always be compared in an apples-to-apples fashion. IBO Speed is just one piece of the puzzle that warrants adequate attention when selecting the bow that best suits your needs.
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