Monthly Archives: August 2016

Wanting to Try a Compound?

QandA logoI had a Recurve student write to ask:
I’ve been thinking about compound bows, is it a big difference shooting one and another?
If I wanted to buy a compound bow what would you suggest? (Not that I’m going to buy one, I just want to check prices and everything else)

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Oh … boy, oh boy, oh boy! There are big differences between compound bows although they all operate on the same principle. The basic design of a compound bow (there are many variations) builds in a mechanical advantage by not attaching the bowstring directly to the limbs. The bowstring is attached only to the “eccentrics” at each limb tip which can be as simple as a pulley with an off-center axle to fantastically complex freeform shapes, but which all have the same role. The eccentrics are connected to the limb at the other end of the bow through the means of a cable. When the bowstring is drawn, the eccentrics rotate and act as levers to bend the limb opposite via its cable. Once the rotation gets past a certain point, the force of the pull on the cable is thrown onto the limb and the only force required to keep the bow drawn is the force need to keep the eccentrics rotated, which is a small fraction (one fifth to one third typically) of the “peak weight” of the bow. Because of this “letting off” of some of the draw force, compound bows are made with substantially harder to bend limbs than recurve bows, allowing them to store more energy that other bows of the same draw force.

Pros and Cons of Compound Bows
First of all they are quite a bit heavier than recurve bows. This makes them more stable when shot (improving consistency) but makes them harder to lift up shot after shot (especially for youths).

• Because of the letoff, the stress on the archer at full draw is much less and more time is available to aim.

• Because of the design of the bow, the bow has its own draw length! The string, when pulled, goes back only so far and stops. That “stop position” is adjustable and must be carefully adjusted to fit the archer’s draw length (which will be different from his recurve draw length, even if still using fingers on strings). Some bows have only slight DL adjustments (circa 1/2˝) and require new parts (draw length modules) to make larger changes. Most bows have several inches of DL adjustment, and some of the new ultra-adjustable bows have many, many inches of DL adjustments (and draw weight adjustments, too).

• Virtually all modern bows are designed to be shot with mechanical release aids, which have a technique all to their own to learn (it took me three years to master release technique).

• Most modern compound bows have been designed to be shot in bowhunting environments which means they are short … very, very short. The lengths of compound bows are measured from “axle-to-axle” (aka ATA). When compounds were first invented, the ATAs were 48-54˝. All of my compound bows that I shoot with my fingers on the string are in the 46˝ to 48˝ ATA range. Most modern compound bows are less than 35˝ ATA, which means the string is at a very sharp angle if you try to draw the bow with a tab and fingers. This sharp angle causes “finger pinch” which is very uncomfortable (not so much at full draw, but definitely at the “peak weight” of the bow you must go through to get to the more comfortable “holding weight”).

• Kid’s compound bows are often “zero letoff” meaning they don’t have their own draw length, they just keep going like a recurve bow (although typically the draw weight does not go up in the latter part of the draw). These bows do not have to be constantly adjusted to the ever increasing draw lengths of fast growing kids.

By all means, try a zero letoff bow (e.g. a Mathews Genesis), their very low draw weight makes the finger pinch of these short bows endurable.

• If you want to try a “real” compound bow (aka one with letoff), ask somebody who is your height, as they will have a draw length roughly your own. You want a very (Very!) light drawing bow to try first and they are rare. If the someone you ask has a typical bow they will have a peak weight of 55# to 70# and you can hurt your shoulder just trying to draw such a beast. So ask someone what their draw length is and what their peak weight is. You are looking for something 45# or less. So, the prime candidate for you to ask is a tall woman. Most people are willing to let you give their bow a try, but if they say “no” they are not being rude, so do not take offense.

• This is very, very important (especially with modern bows). Once the bow reaches “peak weight” … let’s say #45 of force, it will rapidly become much less than that, say 15# at full draw. This is such a shock to people expecting for the draw to increase and increase as it does on recurves and longbows, that they are shocked and let go of the string, dry-firing the bow. This can damage the bow if you do it and will be really, really embarrassing, so on your first draw (always with an arrow), draw and let down, do not even give your fingers permission to open.

• If you are looking to buy a compound bow, I suggest investigating the ultra-adjustable bows first. You can turn the draw weight down to a very low value for learning and then up later. You need to make sure that the bow’s range of draw lengths includes yours! A bow I am currently reviewing is the Kinetic Rave bow which is built in Europe (where this student is located) and there are quite a few others. Beware! Not all draw weights are available at each draw length. I am aware of only one manufacturer who is claiming they are for their bow (the Parker bow company) but they haven’t returned any of my emails, so I can’t vouch for that. You can download the Owner’s manual for almost any bow now from the Internet and it is well worth the research to do so.

A Final Note
The best case scenario is to have a large archery shop nearby with a knowledgeable staff. If you tell them what your interests are, they can measure you up and show you some of your options, which you can also usually test shoot. Of course, they are not doing this for their health, they are trying to sell you something. So, don’t go and find the bow you want on the Internet for $10 cheaper and stiff your local vendor. The pre-sale service and post-sale service you are getting are usually invaluable. You do not get those through Internet purchases. And, if you don’t spend some of your custom at your local shop, there won’t be one soon (this is the predicament of this questioner—no shop, no range, no club nearby).

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I found this great article about the role coaches play in the success of star athletes. Since they wanted US$500 to re-post it here, I am just adding a link.

FYI, for non-English speakers “FYI” is shorthand for “For Your Information”

Coaching Can Make or Break an Olympic Athlete


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Archery Ignorance on Display! Argh!

I guess I should be grateful that Scientific American chose to write a piece about the inclusion of compound archery into the Olympic Games (Compound Archery Shoots for Olympic Inclusion), but it is difficult to do so when the execution was so poor.

Consider the following statements:
In order for the International Olympic Committee (IOC) to consider adding a new event to its roster, the event must be distinct from other Olympic events. Competitive compound and recurve archery differ technically and also procedurally, with different point systems and rules used in each country. Compound archers generally shoot at a six-ring target with a diameter of 80 centimeters from a distance of 50 meters whereas recurve archers shoot at a 10-ring target with a diameter of 122 centimeters from a distance of 70 meters.

Hello? The international archery federation, World Archery (formerly FITA), sets all of these rules and they are all quite arbitrary. Why compound archery, the archery that is more precise, shoots at a distance that is only about 70% as far as the recurve people shoot is illogical at best. They compensate by using a target that is 66% as large, but a recent world record was set in the compound ranking round that was 1 point off of a perfect score. Soon we will be up to our hips in perfect scores. The compound people could be shooting at that same target at 70 m or farther and it would be a fair test, but apparently it is too important to salve the egos of the recurve community. (Those gaudy score the compounders are shooting? Well, they only shoot at 50 m and …)

Another factor the IOC considers when evaluating a new event is whether the athletes—not their equipment—are scoring the points and setting records, Dielen says. That is technologically where compound and recurve archery deviate most. Compound bows have a mechanical release aid that assumes some of a bow’s draw weight and also come with a magnified scope, which together make the sport less about physical power and more about shooting accuracy. Recurve bows are more about a complete performance, requiring more physical strength to pull back and hold the string until the arrow is shot.

Hello? The release aid takes none of the bow’s draw force, none! It passes all of it through to the archer. It is physically impossible for it to assume any of the draw weight because it is only in contact with the bowstring and archer. Where is the force it “assumes” supposed to go?

So drawing a 50# recurve bow requires more physical strength than a 60# compound bow? Holding up a 8-9 lb compound bow at arm’s length requires less strength than holding up a 6-7 lb recurve bow? Plus the 60# limitation is by rule. If that rule were to be lifted, you would find any number of archers at draw weights over 60#. Also, why are compound bows limited as to draw weight when recurve bows are not?

And so what if the compound archer has a magnifying lens in his sight’s aperture. That lets him see the target a bit clearer by does not help the archer hold the bow more steady. In fact it leads archers to try to reduce normal motion at full draw (a fool’s errand), thus requiring additional training to get them to accept that.

Recurve shooters must also take into account the archer’s paradox, or the phenomenon that arrows take a curved and undulating path through the air after leaving the bow. This requires skill on the part of the archers, as they need to shoot slightly off to one side in order to hit their target. “The compound bow is a much more efficient system,” says American recurve archer Zach Garrett, who will represent the U.S. at the upcoming Rio Games. “You don’t have to worry about how you make the string leave the arrow.”

This doesn’t require skill on the part of the archer as the correction for the archer’s paradox is set into the bow when the centershot of the bow is set (and matched with a appropriately spined arrow). The archer does nothing special. Consider the poor compound archer by comparison. The recurve archer’s arrow is off of the arrow rest (and therefore no longer touching it) after the arrow has traveled about a third of the way to the point where it comes off of the bow string. Because of the archer’s paradox, the oscillating/undulating arrow bends around the bow so that the fletches pass by the arrow rest when they are at a maximum extent of the oscillation thus making clearance problems with a well-setup bow moot. But the poor compound archer has his arrow sliding along the arrow rest virtually its full length and even if the arrow “lifts off” of the rest, it is still close enough for the fletches to hit the rest as they go by, thus deflecting a perfectly aimed arrow making it a less-than-perfectly aimed arrow.

Compound bows show smaller group sizes at any distance compared to recurve bows for really only three reasons. The compound bows, being heavier, have more inertia and hence are less likely to move or move less than lighter recurve bows during the critical phase when the bow is pushing the arrow out of the bow and the bow is being held in one hand only. The second reason is letoff. The compound bow has eccentric wheels built into them to cause the bow’s peak weight to be reduced to a small fraction of the bow’s peak weight at full draw. This gives the compound archer more time while being under less tension/stress to aim the bow and release the string. The third reason is the mechanical release aid. It provides a cleaner lose of the string, creating less variation in a set of shots. But release aids aren’t a cheat. They are only used by archers competing against others also using a release aid. And they are not easy to use, far from it. From the first time I used a release aid, it was three years before I felt I knew how to use it properly.

This article did correctly address many of the issues associated with the expansion of an included sport (archery). But they quoted a World Archery officials and an Olympic Recurve archer. Could not a compound archer have been consulted or a compound coach? And while the officials quoted are two of the more knowledgeable ones, this is the organization which banned “shoot through” cabling systems for compound bows for a time for fear that the archers could brace their bows by pressing their bow forearm into the cables. (For the compound uneducated, doing such a thing would create large quantities of unresolved forces that would make even hitting the target at all quite an accomplishment.)

So, thank you Scientific American for the exposure for compound archers. But I can’t thank them for all of the mistakes riddling their article.


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Another Example of Archers Getting Screwed

I received an urgent email from one of my students who discovered that one of the locking screws from the rear of the limb bolt on his recurve bow was missing. He didn’t know how long it had been missing and he had been shooting a great deal so his concerns were twofold: was it safe to continue shooting with that screw missing and how was he to find a replacement?

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Top Limb Bolt showing missing locking screw (top), Bottom Limb Bolt (bottom)

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For those of you who do not shoot modern recurve bows, the screw being referred to is a common part on “adjustable limb pocket bows.” Compound people know that turning the limb bolts in or out creates more or less draw weight, respectively. It has only been recently that this feature has been added to recurve bows. A common mechanism designed to accomplish this involved taking the limb bolt and drilling a hole in the very end and tapping it to accept another, slightly oversized, screw. The drilled and tapped end of the limb bolt has several saw cuts made into it and then it is inserted into the bow. Through a hole in the other side of the riser, the “locking screw” is screwed into the newly tapped hole, causing the end of the limb bolt to spread out in its hole, effectively locking it into place.

Compound people don’t have locking screws of this nature (although some models have used a kind of locking mechanism). Because three-piece recurve bows are typically dismantled after every use, they need some sort of locking mechanism, otherwise the limb bolts could move around while the bow was being jostled while traveling in your car. Compound bows are not dismantled after each use and the tension on the limbs tends to keep the limb bolts in place (although it is wise to index then with marks on the bolt heads to show whether they have turned or not).

So, the residual vibration from shooting this recurve bow caused the “locking screw” to wiggle its way out and fall to Earth. (I keep a strong magnet available to find small iron-based parts in the grass. Sliding such a magnet around where one shoots frequently might turn up the missing part.)

Is it safe to shoot without the locking screw? Yes and no. Those limb bolts are often quite tight all by themselves. But if the vibration left over from shots causes the limb bolt to turn, you are changing the tiller setting of your bow which will effect the size of your groups, etc. Nobody wants their bow to give them poorer feedback on how well they are shooting, so, clearly, it is in any archer’s best interest to replace that screw.

Here is where archers have been screwed in the past. It was almost impossible to obtain replacement parts for bows. Local vendors didn’t stock them and even their manufacturers didn’t always stock them. Once a manufacturer has made a “new, improved” model that doesn’t contain that part, they don’t have an incentive to maintain an obsolete parts inventory. When you sell millions and millions of units, you can have a thriving parts industry serving it, consider auto parts stores and restoration auto parts companies as examples. But if you don’t sell millions. . . .

So, I would recommend that archers remove the back screw from the other limb (remember to hold the front screw in place while doing so) and take it down to a good hardware shop to see if they could get a replacement (or two or three if they are cheap). The store should be able to check the threads to see whether they are metric or Imperial/Standard/English/SAE. The bow companies almost never sold spare parts but you may be able to get on the phone with customer service of said manufacturer and talk them out of one. If you had a good relationship with them, you might just get what you want.

In this case it turns out that Lancaster Archery Supply carries the needed part! They also carry replacement limb bolts for Hoyt and Win&Win bows. They aren’t cheap ($49.99 for a pair of limb bolts!) but at least they are available.

Addendum For you history buffs, before the adjustable limb bolt bows were available, people did adjust their bow’s draw weight and tiller but it was a clunkier process. Since limb bolts were just plain bolts, archers would back the limb bolt out (or nor screw it in as far) and then slip tiny wedges, also called “shims,” between the limb butt and the pocket, then tighten down the limb bolt. If you shimmed both sides of the limb butt equally, you adjusted the draw weight of the bow (downward, slightly). If you shimmed the top limb differently from the bottom limb, you were adjusting the bow’s tiller. If you had a larger shim on one side of the limb bolts than the other, you were actually rotating the limb (slightly) which could be enough to compensate for a slight twist in the limbs.

One can argue that the advent of the adjustable limb pocket systems currently available were the result of too many bows being returned to manufacturers when initially bought due to very slight limb twists and tillers being out of spec. With the adjustable limb pockets this small issues could be adjusted out as a matter of course. I suspect that the “spare parts” available in Lancaster’s catalog (Bless LAS!) are there because of so many of them either wearing, or falling, out.


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“Three Fingers Under” is for Beginners, Right?

There are tremendous advantages to a “three fingers under” string grip for beginners. Its only disadvantage is a loss of distance/cast. Consider the photo below.

Christine Bjerendal of Sweden (2016 Olympics)

This is Christine Bjerendal of Sweden. She competed in the 2012 Olympic Games (London) and she is currently competing in this year’s Olympics. Please note string grip.

Yes, there is a loss of distance/cast with this grip but there are also offsetting positives. Just because we start beginner’s with this string grip does not make it a “baby grip,” a grip adults would be embarrassed to use.


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Want More?

I have been watching the Olympic Archery coverage online, not because I am particularly interested in the outcomes (I am not.) but out of professional interest. Yesterday I watched the quarter final through medal matches for the men’s team competition. Until the medal matches, the team with the better alignment won the matches. But in the medal matches, it was different. In those the team that was mentally stronger won, possibly because the technical differences were much smaller. The winning Korean team showed me something I hadn’t seen from them before: mental toughness. In the past they displayed their technical excellence but crumpled under pressure. Not so yesterday. I can not imagine them being beaten by another team when they perform like that: almost perfect technical execution with mental calmness and security. A near flawless performance.

Now, if you want me to post more, I need ideas as to what you want to know. If you will send me questions or ideas for posts (use my personal email I will do my best to answer them and if I cannot I will do my best to find someone who will.



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