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Note 1: How Calculated Peak Bow Weight is Determined
Recurve and Compound Bows. The Easton Shaft Size Chart was set up for archers using:
- Recurve or longbows with finger release
- Compounds bows without overdraw, and with:
- -Release aids
- -50%-80% let-off
- Steel or Fast Flight cables
- High Performance bows over 43" in length
- Fast Flight string
Variables to the "Standard" Setup:
If your equipment differs from the setup described, the variations may affect the
perfomance of your bow enough to require a shaft size other than the one you would
determine on the chart. Before using the chart, figure the effective weight of your bow
(called the Calculated Peak Bow Weight) using the bow weight additions or subtractions
listed below next to the "Variables" that apply to your equipment. Use this
Calculated Peak Bow Weight to select your corrent arrow size on the chart.
Variables to the "Standard" Setup:
- Compound bows with finger release - Add 5-7 lbs.
- Dacron string - Subtract 3-5 lbs.
- Overdraw Bows. To select the right size arrow shaft from the chart, the greater energy
stored (because the draw length is longer than the shortened arrow length) must be
accounted for by using the chart above.
- Compound bow lengths less than 43" and drawn over 28"- Add 4-6 lbs.
Variables to the "Standard" Setup for Recurves:
For each inch your Draw Length is over or under the AMO-Standard (28"), add or
subtract respectively 2-3* pounds of bow weight.
*Approximatey two pounds per inch for bows 40# and under,
and approximately three pounds per inch for bows over 40#.
Overdraw bows
If you are using an overdraw, make the above calculations (if any), and then multiply the
Calculated Peak Bow Weight of your bow by the appropriate factor listed below.
| OVERDRAW AMOUNT |
1" |
2" |
3" |
4" |
5" |
For 60#-70# Actual or Calculated
Peak Bow Weight, add to bow
weight-(or use factor below) |
1# |
3# |
6# |
9# |
12# |
For any bow weight, multiply you
Actual or Calculated Peak Bow
Weight by the factor to the right |
1.02 |
1.05 |
1.09 |
1.13 |
1.17 |
The chart indicates that more than one shaft size may shoot well from your bow, you
may decide to shoot a lighter shaft for speed, or a heavier shaft for greater durability
and penetration. Also, large variations in bow efficiency, type of wheels or cams, bow
length, string material, and release type may require special bow tuning or a shaft size
change to accommodate these variations.
"Shaft Size" column - indicates suggested shaft sizes.
"Shaft Model" column - designates arrow model.
"S" = XX78(r) Super Slam(r) shafts. (7178 alloy)
"75" = XX75(r), Autumn Orange(r), Easton Classic, Advantage,
Camo Hunter(r), GameGetter(r) II and GameGetter(r) (7075 alloy)
"E" = Eagle(r) shafts (5086 alloy)
"ACC(r)" = Aluminum/Carbon/Competition shafts
"Shaft Weight" column - indicates bare shaft weight only.
To determine total arrow weight, add the weights of the shaft, point, insert, nock and
fletching. Where two Aluminum shaft models are shown for one size, the weight listed is
for the XX75. Letter codes A-C listed to the right of shaft weight indicate the relitive
stiffness of each aluminum shaft within that "Shaft Size" box ("A"
being the stiffest, "B" less stiff, etc.).
Tuning-Although Easton has attempted to consider most variations of equipment,
there are other style and equipment variables that could require shaft sizes other than
the ones suggested. In these cases, you'll need to experiment and use stiffer or weaker
spine shafts to fit your situation.
Determining Actual Peak Bow Weight
Determining Draw Length
Your Draw Length is used to determine your Actual Peak Bow Weight for recurve bows, and to
select the proper draw length setting for compound bows. To determine your Draw Length,
use a lightweight recurve bow with an extra-long arrow and have someone mark the arrow at
the back (far side) of the bow while you are in a comfortable full-draw position. Your
Draw Length is the distance from the mark to the bottom of the nock groove.
Compound Bow:
Determining Actual Peak Bow Weight.
To shoot properly, the maximum draw length of a compound bow must be set to your Draw
Length. A compound bow reaches its maximum or peak bow weight before reaching maximum draw
length and then "lets off" in draw weight 50 to 80%. This reduced weight at full
draw is called the "holding weight." The Actual Peak Bow weight of your compond
bow can be determined on a bow scale at your archery pro shop.
Recurve bow:
Determining Actual Peak Bow Weight.
Actual Bow Wight (maximum of "peak" bow weigth) of a recurve or longbow is the
force (in pounds) to pull your bow to your full Draw Length. See "Determining Draw
Length" information above. Then measure the force required to pull your bow to your
Draw Length ( most pro shops have a bow scale). The AMO-standard bow weight is usually
marked on the lower limb or handle.
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