Determining the correct string length needed on a given bow can be confusing. It is one of the most common questions I am asked. Correct string length is needed to achieve proper brace height on a traditional bow and it is needed to achieve the proper mechanics on a modern bow. In this article I hope to give enough information so you can select a string length that is at least a good starting point.
With any style bow the most fool prove way to determine correct string or cable length is to measure the one you have. If the brace height and mechanics of the bow are the way you want them you can just use those lengths, measured from end to end. If you want the bow’s mechanics or brace height to be different then the lengths will need to be adjusted accordingly. Of course this is pretty much common sense and you probably already knew all that. The real problems come when there is no string to go by.
Here is the procedure I use to determine replacement string or cable lengths on bows that do not have the strings or cables already on them.
1. Use the factory numbers given on the bow. Some notes regarding this:
A. On some bows(such as Hoyt) the cable length does not include the yoke.
B. The numbers on the bow may be incorrect.
2. If there are no numbers on the bow or you feel the numbers are incorrect call the bow company and ask for tech support. Have the bow with you when you call and it is good to have a tape measure handy to answer any questions the tech person might have about the bow.
3. If the bow company no longer exist or if for whatever reason you cannot get the string or cable length you will have to do some educated guessing. You will need these items: some type of bow press; a piece bow string, fishing line, thread, etc. to use as a gauge; tape measure and a helper.
A: Put the bow in the press and put it under pressure.
B: Make a loop on one end of the piece of string or thread you have.Put the loop over the string peg on the cam. Wrap it around the cams and pull it to the other string peg.
C: Get your helper to hold the cams so they look like they would when the bow is actually strung.
D. Measure the brace height, adjust the bow press until you get the desired brace height. Your helper will have to keep the string tight and the cams indexed correctly while you are doing this.
E. When you get the desired brace height mark the string end opposite the loop end that you made. You can use a magic marker or whatever to do this. Mark the string on the far side of the peg.
F. Take the string off and measure it from the end of the string loop to the place you marked. This is your string length.
The above procedure works for cables as well.
Traditional bows are somewhat easier. This is the procedure I use for them.
1. If the bow has a bow length written on it such as AMO 60″ then you can use that as your bow length.
2. If the bow doesn’t have a bow length written on it or you want to make sure the bow length that is written on the bow is correct then you can measure the bow as follows. Measure the bow on the belly side from nock groove to nock groove, following the contour of the bow. This is the correct way to measure bow length.
3. From the bow length subtract 4″ if it is a recurve and 3″ if it is along bow. This is the string length you will need to start with. Two examples are a 60″ recurve would take a 56″ string, a 64″ longbow would take a 61″ string.
Keep in mind these are just starting points for string lengths and once you install a string you may have to adjust string length to get the desired brace height. The majority of the time though the string will be just right
I hope this has helped you in your quest to be a better archer/bowhunter.
Good Luck and Good Huntin’
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