Advanced Bow Stabilization

Easton Technical Seminar

George Tekmitchov, Easton Product Development Engineer
Originally presented at the 1993 Arizona Cup International Tournament
Revised January 1995

History of Stabilizers

In 1961 Earl Hoyt introduced the first Pro Medalist with Weight Platforms - what he called a "torque stabilized" bow. Previous to this target archers had two styles. One was what you might call the "White Knuckle" (exemplified by longbow champion Larry Hughes and Howard Hill among others). This involved a strong grip on the bow. Another was the "natural approach", letting the bow react naturally, flipping to the right for the right-handed archer who held the bow loosely.

Later, Mr. Hoyt added torque-flight compensators or TFC's, to what we today would consider to be the top and bottom rods of the stabilizer system. This cushioned the effects of the stabilizer system and made for a nicer feel after the shot.

Other manufacturers later added their own refinements. For example, there were so-called 'active systems'. In the late 60's Ben Pearson had stabilizers with mercury suspended in a small barrel at the end of a slender parallel rod. The Lord Mercury bow had mercury tanks in the riser. The mercury added lots of mass and also absorbed vibration because it was liquid.

Hydraulic-damped and dashpot-damped stabilizers soon followed. Hydraulic damping uses oil, water, or other liquids besides mercury in a baffle chamber. This helps absorb energy, particularly energy which would otherwise result in noise, so for a while such stabilizers have been seen on hunting setups. Their main advantage is that they are much less expensive than mercury damped stabilizers. Foam and sand damping was used later and is quite common today in stabilizers such as the Bomar and Golden Rod. More advanced systems such as the Easton VRS use a "dry liquid" made up of millions of perfectly round, microscopic borosilicate spheres.

All of these systems have their advantages and disadvantages.

Fluid-damped units can change their characteristics in two ways. One is temperature related and the other is related to the distance being shot. Some (but not all) of these units can react differently in different temperatures. Most of these units will have the working fluid slosh back toward the bow as the shooting distance increases and the bow angle changes. This can be a problem for some shooters and tuning situations as it can change the balance and feel of the bow at full draw, changing the shot reaction. Sand-damped stabilizers can change their 'feel' drastically over time as the sand grinds itself to dust.

The dashpot-type stabilizer dampeners which use a spring and a weight are mechanical in action. To some people that represents one more thing that can go wrong with the bow. In reality, they tend to be quite reliable. However, they are of limited effectiveness in dealing with the vibrations and extra energy of a high-performance bow.

For many years European archers have used small TFC's which go on the weight end of the stabilizer instead of the base of the rods. Recently some American archers have rediscovered these accessories. These are sold as 'doinkers'. These work well but again, as with normal TFC's they can change their reaction as the rubber ages. The rubber modules are easy to replace.

Many European archers, particularly field shooters, like the feel of the so-called 'swing rod'. Some of the Swedes do very well with these devices, which use longer than normal side rods which are allowed to pendulum off bearings. These give some Olympic style field shooters a feel for when they are canting their bows because of terrain variations.

Finally, some people like very large weight stacks on their rods and some even like rather whippy stabilizers. Both of those were common in to the 1960's. What were those shooters in the 60's looking for in their stabilizer system ?

Some of what they wanted was subjective or feel-related. Some gave a lot of thought to the physics of their setups.

What they got by adding big weight stacks to the rods was...

-Increased moment of inertia to, in their view, let the arrow get out of the bow before its flight could be affected by the torque of the bow.

-Less shock and oscillation following the shot. This particularly helped with recurves that had lots of vertical instability.

-Increased mass weight helped SOME recurve archers (in good physical condition) hold more steadily. Remember, this was at a time when some draw-hold cycles exceeded 10 or 20 seconds. In fact one particular archers' hold time was so long it is said he is solely responsible for the three arrow in 2 1/2 minute time limit. It took excellent physical condition to use that kind of setup through an extended shooting session, and archers were often 'wiped out' after a tournament.

Top FITA recurve shooters don't necessarily shoot that way today.

The best Olympic style archers, such as Jay Barrs, Rick McKinney, Sebastien Flute, Kim, Soo Nyung and Cho, Yeong-Jeon, have draw-hold- release cycles of between 2 and five seconds. In fact some Korean women have a metronome-like 2.7 second shot.

Without getting into the various philosophies of aiming or holding time, the fact is top Olympic archers in the world today have reasonably fast draw-release cycles. They are not holding and bearing down on the target, trying to aim finely, for a long period of time. Their shot can be summed up as 'up...on... and gone."

Part of the reason they can do this is their stabilizer system balance usually works in harmony with their own personal feel and bow tiller. There is harmony between what they feel and what they are doing.

Specifically, these archers use stabilizer systems and tiller balance combinations that helps them get on target as smoothly and as fast as possible.

And this is what one might call the first phase of stabilizer function.

When you get to full draw, you want that nice comfortable feeling right away. If you are trying to emulate those top shooters, you want your draw to your anchor point in a very linear manner... just like you want your arrow to fly. And there's a lot that can be done with stabilizer balance to help you do that. You also don't want to waste energy, time and that nice muscle line-up trying to get that bow settled down, twisted around or pushed up or down to get the pin in or ring around the gold. You want to be able to draw on target, and not worry about fighting your bow.

One way to get that which has been successful for many shooters is with a stiff, light stabilizer rod like the Easton A/C/E rod, the Shibuya Mushashi/Kojiro, Angel Parallel Rod, Carbofast rod, or Yamaha URS. These and some other rods all have a number of common factors.

1. They tend to be quite light for the most part.

2. They are all quite stiff, made with carbon fiber or Aluminum-carbon. Some also have a Spectra or Kevlar fiber wrap for cosmetics.

3. They are parallel, not tapered. This has some definite effects we'll discuss ahead

4. They can be used with and without TFC's, swing bars, V-Bars, and other accessories.

What do these stiff light rods do for the target archer ?

Let's look at the physics concept of inertia for a moment. I know most of you know what inertia is but for the sake of the discussion let's explain it as the tendency of an object that is stationary to want to stay where it is, and of a moving object to want to stay in motion. Inertia is tied to the mass weight of an object. Supertankers take several miles to stop from even a slow speed because of their tremendous inertia.

One important reason you use stabilizers is to increase the inertia of the bow as a system. By using a stabilizer, you are increasing the moment of inertia on the bow's vertical rotational axis. This makes the bow harder to twist and therefore torque (induced by the fact that many of us have a less than perfect bow arm, hand position, and shot reaction) is offset.

On the issue of these stiff light stabilizer rods, because they are light, they maximize the effect of any weight you use on the end of the rod. A light rod with one ounce of weight can be as effective in certain properties as...for example... a heavy rod with two ounces of weight.

Earlier, we discussed the old-time finger shooters who would hold forever and shoot with a dead release.

Today's top shooter wants that arrow gone in a short amount of time. But say that shooter comes through the clicker just as he or she gets hit with a wind gust. That wind gust will give his or her body a push no matter how heavy in terms of mass weight the bow is. But the shooter with a lighter bow... one with less inertia... can get that bow back on target faster.

If you will note, most of the top Korean shooters use relatively little mass weight on their stabilizers. The A/C/E and Yamaha rods they use are rather light.

Some of you might think the heavier bow won't be pushed as much... and that would be true if you were as stiff and unyielding as a rock... but the truth is that wind gust is moving you, not just your bow. So, you want to get it back on target without a lot of effort.

That's another reason for light stabilizer rods. You can put the weight you do use at the ends of the light rods where it does the most good.

So we can see that the first job of the stabilizer is to help you get on target fast and smoothly without a lot of bouncing around or adjustment.

Part of that first job also includes keeping you comfortable while you're on target. Comfort in this context means the avoidance of feelings or perceptions that might interfere with your shot execution. Let's look at one of those anti-comfort factors, namely, oscillation. Many of us tend to have small muscle tremors during the aiming phase of our shots. The longer you hold and the more you try to steady down, the more you tend to have these tremors... one reason top shooters shoot relatively fast. Whippy stabilizer rods which are not stiff enough or have too much weight on the ends tend to pick up these tremors and start oscillating. The shooter feels the oscillation, bears down more, creates more tremors, more oscillation, until pretty soon the poor shooter is standing there shaking like a leaf... and you can't tell whether the shooter is shaking the bow or the bow is shaking the shooter.

Light, stiff stabilizers with the proper weight and vibration absorbing characteristics can help absorb those small muscle tremors before they can interfere with your feel.

Another big comfort factor for the finger shooter is string pressure distribution on the fingers. Proper bow balance, which is determined by mass weight and static tiller, can do much to make your finger pressure more consistent and reproducible as you shoot each arrow.

Now, we're moving into the actual 'release phase' of the shot. This is where today's stabilizers don't really function too differently from those of the old days.

If you have seen Easton's high-speed videos, you may have noticed that the stabilizers don't seem to be doing much in the 15 milliseconds or so the arrow is coming out of the bow. But the stabilizers are increasing the moment of inertia of the bow, decreasing the tendency to twist to one side or another during the shot. You might think of this as the second phase of stabilizer function.

Finally, there's the third phase.

When the arrow is a couple of meters out of the bow, all stabilizers start a good deal of oscillation. That's where some of the energy of the bow is going, getting dissipated as motion, heat, and noise. How much of that energy is transmitted as vibration and shock back to your bow arm helps determine the overall feel of your bow. This can have an impact on your mental game, your ability to resist fatigue during extended shooting, and even the durability of some of your accessories such as your sight. Stabilizers can be designed to help soak up that energy faster or more smoothly. Stabilizers can also be set up to react in different ways.

The bow reaction as the arrow is part way down range largely depends on how the stabilizers are set up, as well as the design of the rods and accessories themselves.

A properly set up stabilizer system keeps the bow from twisting sideways, flipping over too fast, kicking the top limb toward the archer, or any of the other negative, follow-through interfering things you may have experienced. The properly set up system should help the bow move positively and naturally toward the target, as if the bow were trying to follow the arrow to the ten ring.

With all of this in mind, you may wonder, what's the best setup ? The best answer may be the best setup is the one that works for YOU. Go ahead, and experiment, because in the final analysis, the best stabilizer system is the one that works best for you as an individual archer.

Only experimentation and time can prove which configuration is best for you as an individual.

Following the general principles outlined above may speed your search for the 'perfect' system !

The preceding Stabilizer Seminar is provided to the Internet Community by myself, and is NOT an official publication of Easton, Inc.
Consider this to be a standard disclaimer !!

George T.
Easton Van Nuys
California, USA

rising, falling at force ten we twist the world and ride the wind.