The Basics of Compound Bows
1.Top Cam/Idler Wheel (on single cam bows)
A compound bow is simply a device that stores and transfers energy. There are not a lot of moving parts and it doesn’t take a computer to operate it, so you can say shooting a bow is fairly easy. What do I mean when I say a compound bow is an energy storing device? When you pull the string of the bow the limbs are being squeezed inward, and the energy you put into drawing the bow is stored in the limbs. This type of energy is called potential energy. When you release the string the potential energy is transferred into the arrow as another type of energy, known as kinetic energy. The storing and releasing of this potential and kinetic energy is what gives the bow its performance. Now here is what makes high performance bows stand aside from the others, efficiency!!! The more potential energy that can be transferred to the arrow as kinetic energy means a more efficient and quiet bow. If your bow isn’t that efficient then the energy that doesn’t transfer to the arrow will become vibration that will travel through the limbs, riser, and even the accessories on the bow. And this vibration means noise, and when hunting you sure don’t want that.
Since there is not a bow that is 100% efficient then that means even in very efficient bows you will still have some noise. Where do these vibrations come from that create this noise? When you release a bow the string, cables, and limbs create vibration by oscillating back and forth and this happens after the arrow leaves the rest. The quicker you can stop this vibration the quieter you can make your bow. Now how in the world do you help stop this vibration? The answer is rubber!! Rubber absorbs vibration, so by adding this you can absorb the vibration out of your string and limbs, helping quite your bow down. There are several items available on the market that you can install on your bow to tackle the vibration problem, such as string leeches, spiders, whiskers, etc. for you string and cables. Limb Savers work well for the limbs, and you can also install cable guard dampeners and stabilizers for the riser the list goes on and on. There is that other thing a lot of people over look when trying to quiet a bow down. Accessories!!! That’s right vibration does travel into those items as well. There is an easy way to locate noise in your bow accessories, and that is to take a rubber mallet and gently tap the bow starting at one end and working to the other. The sound you want to hear is a “thud” sound, now if you here a “buzz” sound then you have just found a accessory or fastener that is making noise when you fire your bow, and this is where you need to work to eliminate that problem.
Now we were discussing limbs when we were talking about vibration, so this will lead me into the next area of discussion. Split Limbs and Solid Limbs. Some manufactures tend to design there bows to use solid limbs and some split limbs, and each manufacturer will have there argument of why one is better than the other. Such as solid limbs are more durable, offer more torsion stiffness etc, and split limb bows are lighter, faster, and produce less hand shock. Now while these manufactures go out of there way to prove to you why each limb is better than the other, in the real world of shooting each limb performs similar. So beyond looks, you shouldn’t fret over this feature too much when deciding which bow you want to buy.
Split Limbs Solid Limbs
When you go into an archery shop you will notice some bows are longer than others, or if you are looking on our website you will see axle-to-axle lengths posted on the specs. Something else you may have noticed too is that today’s bows are all far more compact then the bows of yesterday. Now some of the advantages to having a short axle-to-axle bow (31”-36”) is that they are more maneuverable (which is good for tree stand hunters) fast, less hand shock (due high limb deflection), and light. One other thing you will notice that short axle-to-axle bows will still be forgiving due to they have generous brace heights. Now before you go and decide on a short axle-to-axle bow you may want to hear about the few drawbacks they have. If you want to shoot with fingers, the angle at which the string will be when the bow is drawn back will cause finger pinching, which is quite uncomfortable, so short axle-to axle bows are intended for the use of a mechanical release. So if you shoot fingers you will want a bow with at least 38” or greater to avoid this problem. Also some tube aligned peeps, get over rotated on short axle-to-axle bows which doesn’t really allow a clear viewing angle through the hole. Just a note to you will find that target shooter will generally stick with a long axle-to-axle bow for that pin point accuracy they want which those bows have, due to being a more stable design.
When you look at the different makes of bows on the market today, you will notice that not all the bows have the same type of system. Here are the different systems that are on the market today.
- Dual Cam
- Single Cam
- Hybrid Cam
- Binary Cam
Dual Cam systems are probably the least favored among archers. Dual cam systems are a symmetrical (both cams are identical) system. Although they are known for having great speed, they also have a lot of hand shock, wasted energy (more vibration), and it is almost impossible to keep a dual cam in synchronization. If you ever notice that when you draw back a dual cam bow you will see that the distance between the cables is very little, when the cables are this close they loose leverage, thus loosing control over the cam. So with this being an issue if a cable stretches .010” then the cam will rotate roughly 4 degrees. Now one good thing with this system is that timing is not a big issue. Incorrect timing will only have an affect on peak weight, let off, draw length. So if the bow is in synch and is out of time a little the bow will still have level nock travel, and still be accurate.
Single Cam systems are probably one of the most favored designs by archers today. The single cam system is an asymmetrical system meaning that the top and bottom are different (Cam on bottom and an idler wheel on top). This is one of the simplest systems out there on the market. One of the most notable advantages the single cam has is lack of synchronization issues. This is due to the fact that the cam controls both the top and bottom halves of the bow string. Now don’t be fooled by advertising, single cam bows do need to be in time, if you talk to the manufactures there are timing marks on the cam. Now don’t get confused synchronization and timing is two different things. String and cable creep can cause timing issues with Single Cams. Poor timing affects nock travel, draw length and let off. One other drawback to a single cam is that if you ever change draw length on the bow, you will mess your nock travel up causing you to have to retune your bow.
Hybrid Cam systems also known as cam and ½ systems are relatively new. Like the Single Cam system the hybrid cam system is an asymmetrical system meaning the top cam is different from the bottom cam. Like the dual cam system, hybrid systems can have an issue with synchronization since each cam controls the string, but the hybrids don’t exhibit the short leverages seen on dual cams so they are not as prone to synchronization issues. Now one problem with the Hybrid Cam system is that if your cams are out of synchronization then you have a hard time telling it by looking due to the cams are asymmetrical. Now as long as this system is in time and synchronized you will have good nock travel with this system.
Binary Cam systems are also a relatively new design. This system is a symmetrical system like the dual cam system. Unlike dual cam systems synchronization isn’t as big of deal. This is because cable length change needs to be severe in order to have a noticeable affect on synchronization, and even if you have a severe problem with a cable the effect is minimal, this is due to the cams being slaved together, where as on all the other systems they incorporate a split yoke that slaves the cams to the limb itself. Like the dual cam system if the cams are advanced or retarded together there is no effect on nock travel or tuneability, however a shooter may detect a change in draw length and let-off the point of impact and arrow flight will be unaffected.
Well I think I have pretty much covered what a compound bow is and what different systems compound bows incorporate. But still just keep in mind that no matter what all you hear about compound bows and all the new technology they incorporate the bow itself is still just a simple machine. And I know that sitting down, especially if you are new to the sport, trying to figure out what bow is good for you can be frustrating. So if you get frustrated or have any questions about compound bows, or what bow might be better suited for you, please do not hesitate to give us a call, or drop us an email. We will be more than happy to assist you.