Buying a Bow? Learn About the Working Parts of a Bow Before You Buy

Whether you’re looking to upgrade your hunting bow for the coming season or are just getting into archery, the information below will help you find the perfect bow to fit your needs.

The Bow Cam Selection

Compound bow A lot has been written about cams (or wheels) over the years. The different styles, shapes and individual features are numerous, but they generally can be narrowed down to five distinct types of bow cams: round wheels, single cams, dual cams, 1.5 hybrid cams and binary cams.

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Each have their own set of characteristics that dictates their best application. Factors that make an archer choose a particular cam style over another are speed, comfort, tunability, quietness and accuracy.

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Round-wheeled bows are the slowest of all compound bows, but they are still with us today for a reason – they are smooth and accurate. Round wheels are reasonably quiet, vibrate very little and are easy to tune. Due to their rainbow-like trajectory, they are not a common choice for hunting applications.

Single cams are matched to a round idler wheel. Their popularity has been such a success that virtually every bow manufacturer today produces a single-cam bow. They are very easy to tune, since there is only one cam that rolls over.

Dual cams typically offer more speed than a single cam, but also require more tuning and maintenance. Both cams need to be synchronized to maximize the bow’s potential.

The 1.5 hybrid cams are a newer style of cam. They are a combination of both a dual cam and a solo cam. The speed of the hybrid cam is oftentimes comparable to dual cams. It functions the same as a solo cam, where the idler wheel is replaced with another cam. The addition of the second cam offsets the movement of the nock as compared with a solo cam.

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Binary cams are similar to dual cams, except both cams are slaved to each other. This means that each cam rotates the same amount when drawing and shooting, making a binary-cam system virtually maintenance-free after the initial tune.

The Ins and Outs of a Bow Cam Let-Off and Adjustability

Compound bow camRegardless of which type of cam you decide works best for you, there are several things to pay attention to when selecting the exact model of bow/cam. Thankfully, most of today’s bows are adjustable for draw length, but how adjustable they are and with what amount of difficulty are two important questions that need to be answered.

It is always smart to have your draw length measured before buying a bow. If you change your shooting style or grow a bit (in the case of an adolescent), draw-length adjustment becomes imperative. Be sure to check the draw-weight and draw-length adjustability of a bow to make sure it will fit you now and in the future.

Let-off is another cam function that needs to be understood to effectively tailor a bow to your needs. When a bow is at full draw, its cam geometry greatly reduces the effort required to keep it there. Let-off is the percentage of the peak draw weight that disappears when you’re at full draw. Common let-off percentages range between 65% and 85%.

If you ever have to hold a bow at full draw for an extended period of time (while waiting for your trophy to present an ethical shot), you will appreciate the lower holding weight of high-let-off cams; however, higher let-off results in slightly decreased arrow speeds.

The Bow Riser is an Important Part of How the Bow Works & Feels

Risers (the handle part of the bow) come in different shapes, designs and materials. Their construction and design greatly influence the price, function and performance of the bow.

Like cams, they have many subtle differences, but the three main styles are reflex, deflex and straight.

Reflex Risers:  are easily spotted, as they curve away from the natural curvature of the limbs (see photo at bottom). This design produces faster speeds, as it reduces the bow's brace height (distance between the string at rest and the center of the riser). Modern-day hunting bows are almost exclusively designed with reflex risers.

Deflex Risers: are the exact opposite of reflex risers. Instead of curving away from the limbs, they follow the curvature of the limbs. This increases brace height and creates a slower arrow speed (all things being equal), but bows with deflex risers are more forgiving to shoot and are generally more accurate (especially for a shooter with less-than-perfect form). Deflex risers are the least common type of risers found on today’s hunting bows.

Straight Risers:  fall somewhere in between. They are technically reflex risers, just with a much less extreme curvature than some of the radical reflexes on the market. They are reasonably fast and forgiving — although, like deflex risers, straight risers have all but disappeared from the hunting-bow world.

The material construction of a riser affects the cost, the weight and the size (grip diameter), but does not really affect the performance, accuracy and longevity of the bow. There are two basic ways that risers are constructed: cast (aluminum, magnesium), and machined (aluminum). Risers also are constructed with lightweight carbon fiber, but these are not nearly as common.

Cast Risers: are every bit as strong, accurate and reliable as machined, and can be had at a fraction of the cost. The only disadvantages are in size and weight. Generally speaking, cast risers are thicker in the grip section and heavier than machined risers.

Machined Risers: are the lightest (for metal) of all the risers, and have a smaller grip that tends to fit most hands better than a cast riser, but they are also more expensive to produce.

Carbon Risers: are lightest of them all, but they are also at the top of the price ladder.

Bow Speed Ratings: IBO

To keep the playing fields level and give consumers a basis for comparison, the IBO (International Bowhunting Organization) standard is used to measure a bow’s speed. IBO speed is figured using an arrow that weighs 5 gr. for every 1 lb. of draw weight. Most manufacturers obtain speed ratings using a 70-lb. bow with a 30” draw length and a 350-gr. arrow. Variables such as draw weight and length, arrow weight and weight added to the string have a large effect on arrow speed. An average hunting setup will likely shoot 10-20% slower than a bow’s IBO rating.

The basic parts with namesof a compound bow,

Which Bow is Right For You?

Selecting the right bow is a personal thing, and the decision will depend a lot on what you will be doing with it. Here are a few things to look for when deciding on a compound bow:

  • Axle-to-axle length (ATA) – This is the distance between the axles of the cams (or cam and idler wheel). Much like the balancing pole a tightrope walker uses, a longer ATA will make it easier to hold the bow in a steady, vertical position. However, if you’re going to be hunting from a ground blind or treestand, or stalking through thick brush, a bow with a shorter ATA will be easier to maneuver. Most hunting bows have an ATA between 31” and 34”.
  • Brace height – Brace height is the distance from the string's resting position to the groove in the bow’s grip. Brace height influences a bow’s power stroke (the distance the string travels) and greatly affects arrow speed. A shorter brace height increases arrow speed, but it also magnifies any errors in the archer’s form. A longer brace height is slower, but since the arrow is in contact with the string for less distance, errors in form are not as noticeable. 6” to 7” brace heights are most common.
  •  Bow weight – As a general rule, heavier bows are easier to hold steady, but can fatigue an archer more quickly. Lightweight bows can take more practice to shoot accurately, but are also easier to carry on hunting trips. The average hunting bow weighs around 4 to 4.25 lbs. without accessories.
  • Adjustability – Again, make sure your bow can be adjusted to your draw length and weight. Most compound bows have draw-weight ranges of 10 to 20 lbs. – you’ll see a lot of 60- to 70-lb. and 50- to 70-lb. bows – but if you’re growing or just getting into archery, there are an increasing number of bows with even higher draw-weight adjustability, letting you start out low and work your way up to your target draw weight. Likewise, most bows have a draw-length range of approximately 4-6”. If you’re done growing, then this is fine, as your draw length will not change. For youths, a bow with a larger draw-length range will be able to adjust as they grow.

Understanding the different features of a bow and applying them to your specific hunting conditions and need makes selecting the right bow for the job much less difficult.