Getting the right size string for your recurve or longbow is critical to getting the best performance out of that bow.
To do so, you’ve got to get a string that’s the correctlength for your bow, and has the correct number of strands.
When figuring out the correct length for your bowstring,you’re likely to come across the acronym “AMO.” This stands for ArcheryManufacturers and Merchants Organization, and it represents a uniform system ofmeasurement for recurve and longbow bowstrings.
Let’s say you have a 68-inch recurve bow. You might think,“Well, I need a 68-inch string.” What you need is a 68-inch AMO string, whichwill actually measure 64 to 65.25 inches long depending on the bow and thestring material.
According to AMO standards, the correct bowstring length for a particular bow is three inches shorter than the stated bow length. That is a good rule of thumb, but it’s not guaranteed to be optimal in every case. The latest modern materials (such as BCY DF 97 or 8125 Dyneema) and string-building methods give us bowstrings that do not stretch nearly as much as Dacron B-50 or Flemish bundle-made bow strings.
Dacron bow strings can measure up to one inch shorter untaught then they would under100 pounds of tension, while a new material, such as BCY DF 97 or 8125, mayonly vary by a quarter-inch.
Using the correct string length allows you to achieve thecorrect brace height to ensure quietness and maximum performance for that bowonce it’s strung.
Brace height can be easily adjusted by increasing or decreasingthe number of twists over a wide range in your bowstring. For example, on a string for a 68-inch bow, anywhere from20-60 twists will produce world-class results in order to get your bow’s braceheight correct.
Usually, the bow will have its length measurement printed somewhere on it. But what if you have a bow that doesn’t indicate its length anywhere? You can measure it for yourself.
Set the unstrung bow on its side on a flat surface. Now measure a longbow from string groove to string groove on the belly (grip facing you) side of the bow. For recurves, your groove-to-groove measurement should follow the curvature of the top limb, run straight over the riser, and follow the curvature of the bottom limb.
That measurement is the length of your bow, and the stringyou put on it should have an AMO measurement to match it. Again, a 68-inch bowgets a 68-inch AMO string.
By understanding this standard, you can then match a stringthat doesn’t have an AMO designation with the proper bow. If a string measures65 inches long, then you know it should be used on a 68-inch bow.
A bowstring is a collection of individual fiber strands bound together by serving. Generally, you’ll find recurve and longbow bowstrings with anywhere from 10-20 strands. The number of strands needed in a bowstring depends on the draw weight of the bow.
Modern bowstrings for recurves and longbows are generally madefrom one of two types of material – Dacron(Polyester) or Dyneema/Spectra (HMPE-High Molecular Polyethylene).
If your bow was made prior to 1990, only use a Dacronbowstring to avoid damage. Dacron ismore forgiving on limb tips and string grooves as it elongates, or gives a bit,on each shot. Dyneema or Fastflight/Spectra bowstrings offer very littlecreep/stretch and higher arrow speeds on newer bows.
Dyneema materials such as BCY’s DF 97 and 8125 offer evenless creep than Fastflight strings made of Spectra material.
Bowstrings made of Vectran or Vectran/Dyneema blend arerarely used on recurves and longbows due to the harshness created by zero creepor stretch.
The number of strands required for your bowstring can varydepending on string material and serving thread. Be careful to check your arrow’s nock fitonto the center serving. It should lightly click onto the string, but notrequire more than a tap on the bowstring to dislodge.
Here’s the strand guide our recurve and longbow experts at Lancaster Archery follow:
For bows with draw weights from 10-30 pounds, use Dacron strings with 10-12 strands or Dyneema/Fastflight strings with 12-14 strands.
For bows with draw weights from 30-40 pounds, use Dacron strings with 14 strands or Dyneema/Fastflight strings with 16 strands.
For bows with draw weights over 40 pounds, use Dacron strings with 16 strands or Dyneema/Fastflight strings with 18-20 strands.
Finding the “perfect” bow string for your bow can make a huge difference with accuracy, quietness and performance. The most important factors are brace height and proper nock fit on the serving.