There are 3 basic types of string materials.
100% HMPE, such as Dynaflight '97, 8125, and 8190.
HMPE blends, such as 450+, 452X, and BCY-X (HMPE blended with Vectran).
And 100% polyester such as B-55, B-500, and B-50.
HMPE materials come in different grades and there are different manufacturers so the quality can vary. BCY uses the Dyneema brand. To give an idea of grades, original Fast Flight was SK65 Dyneema. Dynaflight '97 is SK75 Dyneema. 8190 is SK90 Dyneema.
The higher the grade, the stronger and more durable it is, with less stretch/creep.
The advantage of 100% Dyneema is it's durability and lack of stretch. Disadvantage is when the temperature gets high, it can stretch a little. How much depends on how hot, how heavy the draw weight is, what grade Dyneema, and how many strands are in your string. This material can also reduce hand shock.
Dyneema/Vectran blends offer more stability, especially when it gets warmer. Vectran has practically no stretch. Disadvantage is it's more brittle, so it can cause a string to look fuzzy. On paper, it's a tad slower because Vectran weighs more than Dyneema. On our bows the difference is very small.
Polyester ("Dacron") is safe for any bow. Down side is the lack of durability, and the comparably huge amount of stretch/creep, especially in higher temps. This can be reduced with a higher strand count, but that can also increase hand shock.
How the string is constructed can make as much or more difference as the material used. You can make a decent string from a mediocre material; or you can make a really lousy string from the best material.
Of course the best string is a combination of the best construction and best material matched to a specific bow and draw weight.
IMO the best material on the market today is BCY-X. It's SK90 Dyneema (highest grade available) with a small percentage (17%) of Vectran added for even higher stability. Very stable, very durable, very quiet, with very low stretch or creep. Your bow must be rated for High Performance materials though.
I know some folks have used High Performance materials on old bows not rated for them with great results. Honestly, the only two bows I have ever seen damaged by the string were due to the string not being made properly, but I can't recommend it myself. I haven't seen definitive proof one way or the other, so I wouldn't risk it.
I'm not doubting anyone's results--I just know results can vary. Some may remember B-75 and PENN-66. Those both got rave reviews for a while--some folks got great results. Others had bows ruined due to strings breaking. Both were taken off the market.
That's my two cents. I'm still learning.
Chad
Topic: Differences in string materials (Read 340 times)
