When it comes to bow tuning I hear a lot of people talking about areas that don’t actually matter when it comes to tuning for shoot-ability. It seems the trend now is to tune for results they’ve heard of on ArcheryTalk or someone at their club has mentioned. No cam lean. Stops hitting together. Peak weight perfect to what the bow’s sticker says. None of this has anything to do with how the bow shoots for you and is purely based on a warm feeling, cosmetic touch.
Let’s briefly talk about what tuning a bow is for. The outcome you really want from tuning is for the bow to be more accurate, more forgiving to your bad shots, and help you when your form isn’t 100% exactly the same from one shot to the next. And everyone’s different. Read that last sentence again. That’s the important part here because when we look at tuning the bow we want to tune the bow to the archer shooting the bow. That means that during the process the person who will be using the equipment has to be involved with bow in hand to see what changes to make.
There’s no special formula here that works for everyone. Take me for example, I will tune a bow totally different from a good friend of mine (and well most people) because the grip pressure I naturally put into the bow will always give me a right tear through paper. Totally opposite for most archers considering I’m right handed. So I shim cams the opposite way of most people, move my rest differently, and build my arrows a little differently too. But it works for me and I get my best groupings this way.
So what’s really important and what do we need to look at for tuning?
It’s going to depend on how well you shoot as to how deep down the rabbit hole you want to go. I’m a big believer in all archers benefiting from a good tune on a bow. A newer archer may see a bigger benefit than an advanced archer too. You’re less skilled in repetition as a new archer so the tuning will help your flaws. But with that said, you don’t need to nit pick and fine tune to a point that an advanced archer will because you wouldn’t see the differences in it due to the lack of repeat-ability at your current stage.
Where to start?
Let’s look at the basics here. I’m a firm believer in having the correct tools for the job. Bow press, draw board, draw scale, tools to work on the bow. Start there.
The myth of peak weight
Most people believe they need to painstakingly twist cables until peak weight reads exactly the 60/70 pounds the bow is stated to be at by the sticker. In reality though there’s a peak weight variance of up to 2 pounds less or 2 pounds more than peak weight on the sticker that you’ll encounter. Some of this variance has to do with limbs and their consistency from one bow to the next and also your draw length mod or setting because it affects cam rotation on a cam with multiple draw lengths available. Keep in mind that manufactures test bows at 30 inches of draw length and 70 pounds of draw weight in a lot of cases and anyone outside of that mold will vary. Speaking of draw length, the actual measured draw length versus stated draw length can vary 3/4 of an inch by ibo standards.
What I suggest is looking at the total picture. Measure your peak weight, holding weight with your cams’ draw stops just touching the cables at full draw, and then measure your draw length that you’re getting. To measure draw length you’ll want to measure AMO length which will be from the deepest part of the grip to the string then adding 1 3/4 of an inch to that number.
These three elements show you cam starting position, total rotation, and the correlation to being under or over rotated. If the draw length is too long, your peak weight too high, and holding weight too low; then this is showing that your cams are over-rotated. On a basic level, twists need to come out of the cables here if poundage and holding weight is more off than draw length. If your draw length is more off than the peak weight and holding weight then add twists to the string. You’re looking for a good balance of the correct draw length, peak weight, and holding weight to match the let off percentage on the bow’s cam mod.
The formula for finding let off percentage is:
Peak Weight – Holding weight = X
X / Peak Weight = Y
Y * 100 = % of let off
60 – 12 = 48
48 / 60 = .80
.80 * 100 = 80%
Don’t get too hung up on everything being exact because most of the time they will not all line up due to variances. What I always recommend is dialing in the draw length you need to be at to shoot your best as your primary objective. Then holding weight/let off percentage can be manipulated to get as closely to what you need to hold your best from there.
This is another topic that I see people get really hung up on thinking they need zero cam lean no matter what. In reality you’ll have to have some cam lean on virtually any bow. It may start out with little to no lean but then lean at full draw, or vise versa, but with cable guards being on one side of the bow all the stress and strain of the cables goes to one side of the bow during the draw cycle. This shift in turn moves the cams. The key to this is tuning the bow through paper up close, 2-3 yards, to get a bullet hole with your natural grip using correct placement of the hand into the bow. Depending on the bow you may have yokes to use here or you may have to shim the bow, or a combination of both, to get the bullet hole but that aspect is most important. For me I start with the arrow rest running through the middle of the limb pockets, not necessarily riser, to give a good position to begin. From here you can adjust cam spacing/lean to get the bullet hole you’re needing.
These are some quick, high level areas of tuning and you can definitely go much deeper than this. For me personally I’ve developed a method of tuning my bows through trial and error over the years and tracking results. To know more about my process I can work with you directly to guide you through tuning your own equipment by going here: Coaching Packages