October 2006

Home Bow Mechanic- Fun With Draw Length
by Richard Combs

Archers are often advised to let their sight pins “float,” or wander over ,
the bull’s-eye, and let the precise moment of release come as a surprise.
The subconscious, or so goes the theory, is constantly attempting to center the
sights on the target, and any conscious attempt to center the sights or time the
release will result in flinching, punching the release, target panic, or other accuracy-robbing problems.

This approach works very well for a great many bowhunters, but it is based on
the major assumption that it is impossible to hold a bow steady. Bowhunters are not machines, of course, and holding a bow immobile for any period of time, shot after shot, probably is impossible. On the other hand, it is certainly possible to hold a bow steady for short periods, or (if
you can’t buy the notion of complete steadiness, to at least minimize the size
of the wobble. Look at it however you like, but holding a bow steadier is a very good thing for accuracy.

A major factor in that steadiness is correct draw length. lf you find that you have a difficult time keeping your sight pin on a 3-inch bull’s-eye at 20 yards, and if you are not pulling a draw weight that is too heavy for you, there is a very good chance that the problem is incorrect draw length. More often than not, incorrect draw length means a draw length that is too long. The conventional explanation for this is that archers tend to stretch their draw lengths to get greater speeds. As a general rule, one additional inch in draw length generates almost 10 fps in arrow speed. Competitive 3-D shooters, in particular, often attempt to maximize speed to flatten trajectory, and even bowhunters who do not shoot 3-D competitively have been influenced by those who do.

No doubt there is some truth to all this, but over the years I’ve observed that beginning bowhunters, including those who have only a vague idea what 3-D shooting is all about and who are unaware of the relation between draw length and arrow speed, still have a strong tendency to shoot at excessively long draw lengths. For whatever reason, selecting the correct draw length
seems to be a learned and even slightly unnatural thing.

A long overdue trend in recent years has been to back off on draw length.
With today’s more efficient bows, many bowhunters-and some 3-D shooters—
have discovered that they can achieve as much speed as they want without resorting to longer draw lengths. In any case, smart hunters have always been willing to trade a little speed for greater accuracy. While it is certainly possible to over compensate and move to a draw length
that is a little too short, most top shooters agree that a too short draw length is
preferable to a too long one. How critical is it to achieve precision in draw length? The better shots of my acquaintance, including the most serious 3-D competitors, have a draw length tolerance of
a quarter-inch. Anything shorter or longer than that is immediately noticeable, and they will make adjustments.

Draw Length And Draw Weight
Holding the bow steadier is not the only reason the correct draw length is
important. We mal<e reference to draw length and draw weight as separate characteristics—-which they are—but they are not unrelated. It shouldn’t be surprising that the same draw weight will
be perceived differently at different draw lengths. imagine holding your bow at full draw from a position as far back as you can reach. A draw length that is too long increases the difficulty of holding the weight comfortably, which is one reason the bow is more difficult to hold steady at longer draw lengths. The difference is less noticeable in the case of a too short draw length, but holding bow at full draw from a position in front of the optimum anchor point is also
more difficult. And either position can increase the likelihood of the arm or shoulder problems that plague too many bowhunters.
Perceived draw weight aside, it is difficult to achieve proper and consistent shooting form outside the parameters of correct draw length is a much greater tendency for the string to slap the bow arm. For purely anatomical reasons, this can be a chronic problem for some bowhunters, but excessive draw length is often a major factor. For years I watched a hunting buddy struggle with the problem. He bought custom grips, purchased bows with very high brace heights, modified his stance to an extremely open position, and experimented with some difficult and unusual shooting forms. Finally he tried a draw length that was nearly two inches shorter and the problem disappeared.

Among the more pernicious inconsistencies in shooting form is the tendency to creep forward from the wall before release. Pros have come up with all sorts of antidotes to this, including creep tuning and stops on rests and cams. Clearly incorrect draw length will magnify the problem. Not only is it initially less comfortable to hold a bow at full draw when draw length is off, but the arm, shoulder, and back become fatigued more quickly at improper draw lengths. Fatigue is a major factor in creep.

You might assume that draw length is draw length – that if your optimum draw length is 28 inches on one bow, then it should be 28 inches on any bow. That is conventional thinking, but the folks at Spot-Hogg are not very good at thinking conventionally, and as they so often do, they have a different idea. As Spot-Hogg’s Cabe Johnson recently observed, differences in axle-to-axle length can make a significant difference in optimum draw length. The reason is that shorter bows have a more acute string angle at full draw than do longer bows.

Assume for instance, that you draw your string back to touch the tip of your nose at full draw, with two bows one short and one long. The distance between grip and nock point may be the same on both bows, but the distance between the riser and the string where it touches the nose will be different because of the different string angles. The tendency will be to change the shooting form to compensate- to modify the head angle, change the anchor point, extend or bend the bow arm
more. Those adjustments will probably decrease the ability to hold the bow steady and increase discomfort, not to mention reinforce inconsistencies in shooting form. The bottom line is that,
contrary to conventional thinking, there is no “right” draw length for a given individual. The optimum draw length will depend in part on the bow.

Adjust Draw
Many—though by no means all—compound bow designs offer a range of draw length adjustment accomplished by moving the end of the string to one of several different posts on the cam. Often
the range is three inches, with changes in half-inch increments. With other bows, changing draw length requires changing modules on the cam. However these adjustments are made, they may
have slight effects on let off or bow efficiency, but any loss in these areas will be more than compensated for by the advantages of shooting at the correct draw length. In most cases the bow will have to be pressed to make these changes. Changing draw length will usually require that the bow be returned. (In some cases, simply pressing the bow will require that it be returned.)
For more precise adjustments, strings or cables can be shortened by twisting. Lengthening the string lengthens the draw, and shortening the string shortens it.

The opposite is true for cables:Lengthening cables shortens the draw and vice-versa. Manufacturers of modern, high quality strings usually warn against shortening a string more than a quarter inch or so by twisting, but usually this is enough, especially if done in conjunction with moving the end loop
to another post, or changing modules. One way to reduce the number of twists necessary to accomplish the desired change is to adjust both strings and cables. To shorten the draw length, for
instance, untwist the cable a few turns, then twist the string a few turns.

Draw Length Alternatives
Repeatedly pressing the bow and making adjustments until the precise draw length is arrived at can be a frustrating and time-consuming affair, and not every bowhunter owns a press. Fortunately, there are better ways to experiment with draw length. For starters, the length of many release aids can be adjusted. Almost all wrist caliper releases are easily adjusted. You might object that adjusting the release aid is not really changing draw length, and you would be correct. Shortening the length of a release aid does move the anchor point forward, though. In fact, it accomplishes
all the objectives of shortening the draw length, without the disadvantage of reducing arrow speed. I’m all in favor of maintaining, or even increasing, arrow
speed if it can be done without a downside. ln effect, achieving the proper
anchor point without shortening the power stroke of the bow is a free lunch.
The only caveat, of course, is that the release itself should not be uncomfortably short. Many bowhunters touch the trigger with their fingertips anyway, which is not the best form. In that case,
shortening the release aid is a “twofer,” providing a better anchor point and a positioning of the finger on the trigger that is less likely to contribute to punching the release or even target panic.

Some bowhunters looking for extra 10 fps or so of speed might find that by shortening their release aid, they can actually extend their draw length without changing their anchor point. Don’t need an extra 10fps of speed? Shorten the release aid, extend the draw length, and back off on the draw weight by five or six pounds. Speed will be about the same, but you’ll be pulling and holding significantly less weight.

Bowhunters who feel that their release aid is already as short as it should be can switch to a forward trigger design release. By using a release aid with a trigger farther forward, and much closer to the jaws of the release, it is possible to shorten the release without changing the position of the trigger relative to the wrist caliper to another to another shorter style of release aid.

A similar option is to alter the size of the string loop. (If you’re not using a string loop, you should be) As with the release aid making the loop shorter will move the anchor point farther forward, while making it longer will move it back. If a longer loop makes for a better anchor point, then lengthen the draw length by changing string posts or modules, or by untwisting the string a few turns then shorten the loop. Perceived draw length will be unchanged, but real draw length will be longer with a longer power stroke and more speed.

Finally, bowhunters shouldn’t overlook the effect of grip on draw length.
We’re talking an optimum range of quarter inch in draw length for most shooters. The difference between a wrist high grip, in which the riser touches only a small bit of skin between the thumb and forefinger, and a low grip, in which it is in contact with much of the hand, can easily make a difference of half an inch.

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