Almost all hunters nowadays use the compound bow. The advantage of these bows is that they reduce the force needed to hold the bow back at a full draw. They can reduce the force from between 50-80%. This reduction in force, called the let-off, lets you hold your draw for a longer time than you could a standard long bow. This gives you the time needed to take perfect aim. The let-off percentage is an important factor to choosing the right compound bow for your.
Almost all compound bow makers now offer their products with 1 or 2 cams.
The advantage to the one cam bow is that you do not need to synchronize both cams as you do on a bow with two cams. Instead the wheel at the top of the bow, called the idler wheel, uses 2 tracks that ensure the arrow will travel along a straight path.
Two cam bows come in three different styles; soft, medium and hard cam.
The soft cam compound bow has irregular shaped lobes. This gives the string both a smooth draw and more speed and power.
Medium cams have symmetrically shaped lobes. Both are oval, and while the draw is not as smooth as the soft cam, the medium cam has more energy storage and therefore more speed.
Hard cams have elliptical shaped lobes. While the draw is the least smooth of the 3 cams, this is the fastest of all the styles. These hard cams are called hatchet cams.
As to which cam is best for you? The hard cam takes the most strength to draw back. In addition, the compound bow must be held perfectly still while the arrow is being launched. The slightest movement of the bow will cause the direction of the arrow to be dramatically altered. The soft and medium bows both require less strength to draw the bow back fully. In addition, they provide just as good a shot as the hard cam from about 20-30 yards, which is about the standard length of a hunting shot.
Adjusting the Draw Length
One way to adjust the length of the pull back is with an E-wheel. This wheel has 2 string pegs and the draw is adjusted my placing the string behind 1 of the 2 pegs.
The other method is to change out the string modules that are located on the cams. Both of these methods increase the draw length along with the draw weight. Conversely a decrease in the draw length decreases the draw weight of your compound bow.
The way a cam is designed determines the let-off of the compound bow. Let-off can be as high as 80% and as low as 50%. With a compound bow that has an 80% let off, that means you are only holding 16lbs of weight when the string is pulled fully back. Reducing the hold back weight does reduce the stored energy and ergo the speed of the arrow. The better let-off to have is around 60%. Some compound bows let you change the let-off by altering the cam axle or cam module.
When purchasing your compound bow keep the above factors in mind. Remember the best bow is the one that lets-off just under your chin. In addition you do not want the draw hold to be too strenuous. Good luck and happy bow hunting!