Monthly Archives: February 2013

A Little Bow Geometry

Everything about archery consists of tradeoffs, starting with the design of bows.

Recurve Bow Geometry Diagram
Consider the recurve bow at brace in the figure. The horizontal centerline of the bow is midway between the arrow rest hole and the pivot point of the grip. The nocking point is about one half inch above the level of the arrow rest, so that arrow (depending on size) is attached to the string about 3/8˝ above level and an additional inch or so above the previously mentioned centerline. All of these are examples of many of the various tradeoffs necessary to design a bow.

Basically this results in the archer’s fingers (plus tab), being 2-2.5˝ high, being practically centered on the bowstring (see fingers in diagram in relation to bows centerline (CL) which is also the string’s centerline). The bow hand is on the bottom half of the bow, creating what is called a “tiller” problem. (The word tiller means the same as the word tiller associated with sail boats; it means a thing “to steer.” By holding the bow asymetrically, that is on the bottom half, we in effect have made the top limb longer. Many people adjust for this by turning the limb screws to create a slightly weaker limb on top than bottom. (In the old days, they actually sanded one limb more than the other to make it weaker.) Others address this issue by adjusting the nocking point location, leaving the limb bolts alone. If you move the nocking point up, you are decreasing the leverage you have on the top limb, making it effectively stronger, etc. and apparently only small adjustments in nocking point location are necessary to adjust for the problem that comes from holding the bow on its bottom half.

The same issues come up whether you shoot a longbow, recurve bow, or compound bow. The simplest approach is to set the tiller at “even” and then adjust the nocking point location while tuning (bare shaft test). Tiller is determined by measuring from the top or bottom of the riser to the bowstring (at a right angle), then “tiller = top tiller measurement – bottom tiller measurement.” Typical recurve settings are +1/8˝ to +1/4˝ (string closer to bottom limb than top).

This situation has benefits, though, in that as the bow is drawn, a torque is created hinging on the bow shoulder that helps to raise the bow. Basically the draw is part “back” and part “up” (using the bow arm as a boom.

Full Draw Vectors

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Making the Switch: Compound to Olympic Recurve

I got a question from a new friend, Fern Slack at the Missing Marble Blog (http://missingmarble.com/): She says:

I got a great question this morning from a Facebook friend. He shoots with compound and crossbow, but is interested in learning Olympic Recurve, and asked for advice on how to choose a bow to start

“Fred, my husband has given a lot of thought to this question. We are not experts, but his input makes sense to me. Here is what he said: first, buy the best basic riser you can afford to begin. Put your “investment” money there. There is a good selection of mid-priced risers that have a lot of the same features as the chokingly expensive ones . . . which you shouldn’t buy unless you have decided to stick with it after practicing it awhile.

“Your first limbs should be cheap ones. You’ll want to start at a low draw weight in order to get your form right. Don’t let your pride push you to higher draw weights too fast. Start at 15 -20 lbs, and work your way up to 35 or 40 lbs slowly, making sure your form is not compromised by the extra weight along the way.

“So really cheap 15-20 lbs ones, because you are going to outgrow those fast.

“Once you get to goal weight, invest in better limbs.

“After that, consider a better riser. On the riser, consider the form factor of the grip heavily; go hold a bunch of different ones. Whatever form factor you train your hand to is one of the hardest things to change later.

Okay, I am an expert and I consider this really good advice!

Here are some things I can add.

I suggest that the advice on grip shape are point on: most compound archers shoot with a low wrist grip, often off of the riser itself either by the design of the bow or by removing the grip. I suggest that if you are going to keep shooting compound (no reason not to unless you have a passion to go to the Olympics or World Championships in Olympic Recurve) your bow should have a low wrist grip (or low to medium wrist). You have already trained yourself to evaluate the feel of your bow “in hand” with such a grip so use that feel to inform your Olympic Recurve shooting.

As far as draw weight goes, if you have been shooting a 60# compound (typically with a holding weight of 18-20#) I wouldn’t suggest you start at more than 20#s of draw. Try no more than half of your peak weight as a starting point instead. The reason is you have developed your “archery muscles” and form (including the leverage that is more important than the muscles) and you will overpower a 20# bow, that is make it do what you want rather than you learning to do what it is designed for.

When selecting bows consider the bow’s length, a strung recurve standing on your shoe top should reach roughly to your chin to nose height, with a “little long” being better than a “little short.” The limb’s draw weights are listed on the bow’s limbs as measured at 28˝ of draw (for adults). If your draw length is shorter or longer, the draw will be different by about 2# per inch. My draw is close to 31˝ so my “extra” 3˝ of draw makes any limb I chose be about 6# heavier than the listed weight (weight goes up the farther you draw and conversely weight goes down as you draw less).

With a relatively modern riser (one with adjustable limb pockets) you will be able to adjust your draw weight (down from the listed peak value) by about 10% (far less than the 25-33% typical compound bows provide). This allows you to swap limbs in four pound increments (previous pair maxed out swapped for a new pair of limbs four pounds heavier but backed off will create a roughly two pound draw increase). As a rule of thumb you don’t want to change draw length by more than two pounds at a time once your draw weight has been established. The exception being your situation—an accomplished adult archer starting at a “low draw weight.” After you have established reasonable good form at your beginning draw weight (28-30#) it is fine to jump up and try a 34-36# bow, just don’t add so much weight that you find it difficult to execute. (The extreme example of this is I had an archer jump from a 20# bow to a 36# bow but she had expert advice and was really timid about moving up and so shot the 20# bow longer than she needed to.)

You can recycle (actually reuse or repurpose) some of your compound equipment. For example, if you had a long stabilizer on your compound bow and if it is relatively light (or you can take the weights out of it) it will work fine while you are learning. You do not need V-bars from the get go—Butch Johnson, four-time Olympian, does not use V-bars at all.

You do not need “match quality” arrows from the beginning (although you will if you get competitive). Aluminum arrows, properly spined, work quite well. Since you will have to change arrows quite a bit as your draw weight changes (a change of 5# = a spine group difference in arrows) if you can size your initial arrows to be about 2˝ longer than you require (they will need to be one spine group stiffer per extra inch), you can cut these as you need additional stiffness when your draw weight goes up (a cut of 1˝ = one spine group stiffer arrows, so two extra inches allows you to add 10# of draw, roughly, and only need to cut your arrows down a bit as you increase the weight).

You will have to adjust your shot sequence and form a bit. Recurve archers get closer to the bow than compound archers (you will need an arm guard!). Recurve archers are holding peak weight at full draw so, you cannot afford to dawdle there. You are going to want to use a finger sling or wrist sling rather than a bow sling as you can learn a great deal from the bow’s reaction after the release.

Finally, if you are considering using a coach, the absolute best time to do so is when you begin. If you wait, you will probably spend a good many coaching dollars fixing the problems you unknowingly created by teaching yourself. In my opinion, a coach is someone who you pay. If you just take the advice of friends in your club, well the admonition is “advice is worth every penny you pay for it.”

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Still Thinking Trad

In a recent post I wrote about getting into traditional archery, typically with either a longbow or a one piece recurve bow. Today I had a student on my team struggling a little with his bow setup. When you shoot “off the point,” you line your arrow point up with something in your field of view that gets your bow in position to shoot your arrow into target center. I had made the point over and over that: if you have a “good tune” your “point of aim” will be on a 12 o’clock to 6 o’clock line through the center of the target. Unfortunately my student’s POA was to the right of that line. This means that, since he is right-handed (and everything else was okay), that his arrows were a bit too stiff. Either the arrows needed to be made weaker or the bow had to be made stronger. Since he was shooting a compound bow, we put one more turn on each limb bolt (thus making the bow’s draw weight 1-2 pounds higher) and, voila, problem solved.

This is one of the advantages of compound bows, that they have a draw weight that is adjustable typically over a range that is 25-33% of the maximum peak weight. (They are now making ultra-adjustable bows that have mammoth draw weight ranges, like 5-70#!) But then I thought “You can’t do this with a trad bow, so how do you tune up a trad bow?”

Good question: how do you tune a traditional bow?

To change the draw weight of a traditional bow is no small task, although at one time it was common practice. Back when most longbows were “self bows” that is made of a single thickness of wood or possibly with a backing made of linen or leather or a different wood, bows were often shot a while and if the bow started to take a “set,” that is go from being straight when unstrung to being curved (also called “following the string”) they were often reconfigured. Since the bow taking a curved shape when unstrung lowers its draw weight, it needed a draw weight boost and the way this was done was to cut an inch or two off of each limb tip and have new nock grooves filed in. A little filing and sanding and voila, a new bow, shorter by 2-4˝ and more powerful. (The shorter a piece of wood, the harder it is to bend.)

This is almost impossible to do with a recurve as it messes up the shapes of the curves of the limbs.

Another thing that was done was the limbs could be scraped or sanded to make them slimmer which would result in a bow with a lower draw weight (permanently). You can’t do this with a laminated longbow (or recurve), as it will reduce just the outside laminations only, so they sanded the dges only, creating a limb with less material and thus weaker.

So, let me just say that changing the draw weight of a traditional bow is not a first option and sometimes not even an option at all.

So, how does one tune a traditional bow?

You can adjust two things: the bowstring itself and/or the length of the bowstring.

Tuning with Your Bowstring
In general you can change the length of the string you have and it will change the power of the bow. This is how it works. By adding twists to the string (10, 20, 30, more) you can make it shorter. Placing it back on the bow you will see that the bow is now more bent at brace than it was before and that the string is farther from the handle (the “brace height” is greater). What this means is that when the arrow is shot, the string will stop more quickly and the arrow will come off the string sooner. Since the longer the arrow is on the string, the more energy it absorbs from the bow, so:

shortening the string, raises the brace height and makes the bow weaker
lengthen the string, lowers the brace height and makes the bow stronger.

The effects are not huge but they are significant.

The other thing you can do is switch to a different string of the same length but of different composition. A string can be made heavier (making the bow weaker) or lighter (making the bow stronger) by changing the number of strands. An 18-strand string is 50% heavier than a 12-strand string of the same length and materials. The bow’s energy gets wasted moving the heavier string rather than moving the arrow, so a heavier string makes the bow appear weaker, etc.

And string material changes can make substantial (but not huge) differences. Most older bows use Dacron strings. Dacron, as a bowstring material, is quite “springy” and some of the bow’s energy goes into stretching it rather than into the arrow. The stretchiness also protects the bow when the limbs are slammed to a stop when the string stops them at the end of a shot. More modern bowstring materials have very little stretch in them and transmit almost all of that shock to the bow and the archer. Modern bows have been designed to handle this, older bows not so much. (Do not put a modern material bowstring on an older trad bow, you could break the bow. The new materials are also more abrasive and have been known to cut into unreinforced limb tip notches.)

So, if you have a modern bow with a Dacron string, you can make it slightly stronger by putting in a bowstring made of a modern material, such as Fast Flight (a polyethylene material).

Tuning with Your Arrows
Most of bow tuning is really done my adjusting the weight, inherent stiffness, and length of your arrows. This is true for all bows and is the major source of tuning adjustments for traditional bows.

Once you have bought the bow, fiddling with the bowstring only buys you a little variability. The majority of making a good bow-arrow-archer system is going to be made with adjustments to the arrows. So, be very careful about the bow you buy. I have been known to buy bows with specifications that suit the arrow I want to shoot, not the other way around. Your arrows are more important than your bow to you or the students you coach becoming consistently accurate.

If you are interested I will address the processes used to tune a trad bow. Let me know.

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Q&A To Cant or Not to Cant, That is the Question

QandA logo Coach Kim Hannah of Chicago, IL writes in with a question one of her students came in with: “In my abundant free time (kidding) I have tracked down some DVDs on instinctive shooting. I have noticed that when explicitly or implicitly they all shoot with a slight cant of about 15 – 20 degrees or so . . . not the straight statuesque position of Olympic archers. What do you make of this?

I like inquisitive students and this is a good question! The answer depends on whether your audience is comprised of target shooters or bowhunters. Bowhunters tilt their bows, typically top limb to the right if right-handed for a couple of reasons. This technique, called “canting the bow” allows the archer to see more clearly the bowhunter’s prey, basically because the bow is no longer in the way. Most importantly, it allows both eyes to clearly see the target, providing the binocular vision required for accurate distance estimation.

Now traditional bowhunters, hunting this way (it is not really “instinctive” rather learned through repetition), are not estimating distance using formulas or schemes involving conscious thought but are doing it subconsciously. No matter how it is done, without binocular vision, aka both eyes wide open and able to focus on the target, our ability to estimate distance is very poor.

Now, the reason target archers do not do this is this: when you cant the bow, the bow is rotating in your hand. If your bow has a typical recurve style grip section, it is rotating around the “pivot point,” or the deepest point of the grip. This means that the arrow swings in a quite tiny arc during the cant because it is very close to the pivot point. But if you are using a bow sight, the bow sight’s aperture is swinging in a much larger arc (because it is farther from the pivot point) and you have now messed up both the windage (left-right) and elevation (up-down) connection between the arrow and sight. In other words, the sight only works correctly at the exact cant that you sighted in with. Any other cant introduces error. Since all techniques are subject to “normal variation” (sometimes the cant is more, sometimes less), we have introduced another source of variation into our shooting which makes our groups larger, not smaller.

Consequently target archers are taught to not cant their bows. Placing our bows straight up and down is a direction we can find with some accuracy and variations from it cause small errors. The more we cant the bow, the bigger the error we are talking about.

Traditional bowhunters can get away with a sizeable cant (as much as 90 degrees!), because they are not using a sight and the benefits far outweigh the tiny error introduced. This is further an acceptable technique in that bowhunters are shooting at relatively short distances compared to target archers. Back in the longbow era, typical target distances were 60, 80, and 100 yards. Most deer are taken, for example, well short of 25 yards. Shorter distances means larger errors produce smaller effects in that, once an arrow is off line, the longer it flies the farther off line it gets.

As far as instruction goes, we teach all beginners to shoot with their bows upright as we are teaching target archery. Should the student want to try traditional bowhunting, it is not so hard to learn to cant their bow.

Hope this helps!

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Going Trad

I have decided to post here more frequently. I was hoping those of you following would send in your questions but that hasn’t taken off yet, so I will plow on using my own compass as a guide.

Modern Longbow

A Modern Longbow

Lately I have been thinking a lot about training traditional archers. I have one student on my college team who got so excited when I let him try a longbow that he ran out and bought one. Happy archer, that; he found his bliss!

Generally, traditional archers shoot longbows or one-piece recurves but may shoot “takedown” bows as they are often used by hunters. (Takedown bows break down into two or three parts.)

Trad Recurve

A One-Piece Recurve Bow

Recurve or Longbow?
This is a matter of taste. Recurve bows shoot a little more smoothly and have less “hand shock” (vibration transferred from the bow into the bow hand). Some longbows come with a shelf (see photos) others require you to “shoot off your knuckle,” that is use your hand as an arrow rest. Almost all traditional recurves have an arrow shelf. If the shelf is rounded, it is designed to be shot with the arrow resting on it (usually a soft piece of leather or fur provides the resting place). If the shelf is flat, some kind of arrow rest is needed (often these are just plastic stick-on rests).

How Long?
Both types of bows come in various lengths. The shorter versions are generally used by hunters (less likely to catch on brush or tree branches or bang against a stand) and longer versions for target archers (less pinch of the draw fingers by the bowstring, smoother draw), In general, target archers prefer longbows to be about as tall as they are, while recurve people think a strung recurve bow, stood on one’s shoe top, should have it’s top limb tip reach between the chin and nose.

Longbow Shelf

This longbow has an arrow shelf, note the leather pad installed.

How Stout?  
Archers who have been shooting compound bows often make the mistake of getting a traditional bow of the same draw weight as their compound bow, e.g. “If I can handle a 40# compound, I should get a 40# longbow.” Ahhhn, wrong! A #40 compound bow with 65% letoff has a draw weight at full draw of 14#. The longbow has a draw weight of 40# at full draw (assuming a 28˝ draw length)! (This is the definition of heavy lifting!) Also realize that recurves and longbows get harder to pull the farther back you pull them (from brace!). The listed draw weight of a recurve or longbow is the weight or pull force at 28˝ of draw (for adults, typically 24˝ of draw for youth bows, and many traditional bowyers list their draw weights at the design draw length (as they are often made to order) such as 42#@26˝ of draw). If your draw length is different from this, the actual draw weight will be different. Typically 1-2# of draw is lost for every 1˝ short of 28˝ the bow is drawn and 1-2# of draw is gained for every 1˝ past 28˝ the bow is drawn (this is the rule of thumb for the relatively light drawing bows used by beginners; heavier bows can go up/down 3# per inch, for example).

As a general rule, a compound archer should look at a longbow that is 10-15# lighter than his/her compound. Recurve archers can get traditional recurves or longbows anywhere near their normal draw weight and they will be fine.

Realize that if you buy a longbow or one piece recurve, if you get the wrong draw weight, you will have to buy another bow, a whole new one! There are no limb swaps or limb bolts to crank up or down. So, be cautious when you buy and, if possible, always “try before you buy.”

Arrows: Wood or. . . ?
Many traditional archers use wood arrows. Beginners should not. The reason is that they break easily. I recommend that you start with inexpensive aluminum arrows and after you gain control of your new bow, then try wood arrows. (They are fun to make from parts, by the way.)

Wooden arrows . . . you may need a lot of them as they do break easily.

Wooden arrows . . . you may need a lot of them as they do break easily.

The markings regarding the stiffness of wood arrows is different from aluminum and carbon arrows. With aluminum and carbon arrows, the arrow’s “spine” is usually listed (a number like 720 or 480). This number is simply the number of thousandths of an inch an arrow shaft sags when a two pound weight is hung on its middle. A “spine” of 520 means the shaft sagged 0.520˝ when it was supported at both ends horizontally with a two pound weight hung in the middle.

Wood arrows are more likely to list the spine as something like 35-40# which is a reference to the draw weight range the arrows were designed for. This is tricky though, as you can’t just match your bow’s draw weight to the wood arrow’s rating. The reason is that when the arrow’s are cut, they become stiffer. If you have a very short or very long draw length, you have to adjust things. My longbow is 30# @ 28˝ but I buy 35-40# arrow shafts because my draw length is 31˝ which means I don’t cut the arrows at all! There are charts to help you with this process. Send me an email if you can’t find one.

Horsebow

There are even traditional bows designed to be shot from horseback! (Yes, a galloping horse!)

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How Should Archery Coaches Dress?

I am not trying to set myself up as a fashion Nazi but I am trying to “professionalize” the coaching of archery, so this topic does come up. We think it is important enough that it comes  up in our AER Coach Training Manuals.

Too often I see coaches who have dressed without thinking. We, on the other hand, want to establish a number of things that how you dress impacts on: the validity of coaching fees, coaching authority, perceptions of competence, etc. If you show up to a coaching session in ratty running shorts, flip flops, and a raggedy teeshirt, you aren’t especially broadcasting “professional coach,” now are you?

Here are some of my thoughts:

I Avoid “Archery” Teeshirts Shirts with manufacturer’s logos or which advertise events are what I mean here. If the class is at your club, obviously wearing a club shirt is appropriate. I just don’t want to be giving what appears like equipment advice as a billboard. Fancy shooting shirts are also something I don’t wear. The fact that you are a factory sponsored shooter doesn’t really mean anything with regards to your abilities as a coach.

I Wear Khakis and a Polo Shirt This is a simple outfit that makes you look like a coach. Anyone coming up to the archery field takes one look at you and guesses “that’s the coach.” The whistle around your neck doesn’t hurt, either. Men and women can both wear such an outfit. For really hot weather Khaki shorts are appropriate.

Wear Safe Shoes Students shouldn’t be wearing flip flops, so neither should you be. You are a role model for your students, whether you like it or not. If you tell students they must cover their feet at the range (to prevent wounds from dropped arrows, bug bites, whatever), you will be sending a really mixed message if you violate your own policy.

I am getting a little long in the tooth (a little? all right, a lot) and my comfort is important to me. I don’t expect you to forgoe yours, just to consider how you appear to your students and their parents. There is something to that “dress for sucess” stuff.

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Even More on Coaching Archery is Out!

I just checked and my latest book, Even More on Coaching Archery, is now available on Amazon.com. If you enjoyed, or better benefited from, Coaching Archery or More on Coaching Archery, this is more of the same. Let me know what you think (steve@archeryfocus.com). If you like the book, or any of the others really, I would appreciate you posting a review on Amazon.com. Many people say the reviews really help them decide whether or not to buy a book.

EMOCA Cover (10%)

Table of Contents

On Form and Execution
Using a Release Aid (The Right Way)
Teaching Aiming and Sighting
The Whole and Its Parts
The Pre-Draw
The Pre-Draw Redux
BEST Step by Step #1 Overview
BEST Step by Step #2 The Stance
BEST Step by Step #3 Hooking and Gripping
BEST Step by Step #4 Mindset and Set-up
BEST Step by Step #5 Drawing and Anchoring
BEST Step by Step #6 Loading-Transfer to Holding
BEST Step by Step #7 Aiming and Expansion
BEST Step by Step #8 Release and Followthrough
BEST Step by Step #9 Relaxation and Feedback

The Mental Shot
Shooting in the Now
Mea Culpa
Coaching Four Personality Types

On Coaching
Adapting Standard Form
Shot Planning
A Weighty Matter Put in Balance
The Lines of Archery
Following Up on Following Through
Taking Advice
Finding Coaching Wisdom
The Elements of Winning Archery
Drilling for Archery
The Whole and its Parts
Watch Your Language
Practice Prescription, Pt 1
Practice Prescription, Pt 2
How Relaxed is “Relaxed”?
What’s Your Preshot Routine?
How Compound Bows Mislead Beginners
Do As We Do? Do As They Do?
Coaching Precepts
Serious Questions About Teaching Form
Inexpensive Video for Archery Coaches

On Equipment
Teaching Archery Crafts
The French Method of Tuning

General Commentary
 Do As We Do? Do As They Do?
Just How Important is Safety?
Competitive Age Categories in Archery
Golf Envy
Golf Envy, Part Deux
The New AER Archery Curriculum

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“Brave” Got It Right!

I finally got around to seeing the movie Brave last night. Brave was one of the three archery prominent entertainments that sparked the latest wave of interest in our sport (the other two are the Hunger Games, and The Avengers).

Most archery based media (Lord of the Rings, Rambo (First Blood, Part 2), The Avengers, Arrow (TV), etc.) present a showy archery, typically with poor form and unreal accuracy.

The cool thing is that Brave got it right. Their depiction of archery was spot on. Not only did they get the form flaws of the poor archer’s right, but Merida’s form was impeccable. Plus they showed the Archer’s Paradox beautifully. Congrats to Pixar and whomever their technical consultants were (couldn’t find this information unfortunately).

Plus it was a danged good movie!

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