Confused over string length

[Jakdaw]

Hi, hoping someone here could enlighten me as to the correct string length and possibly explain why there is conflicting information.
The Hoyt manual for my matrix says the recomended string lenght for a 68inch bow is 65inches ie 3 inches shorter than the bow. However all shop sites that I have visited, list the string length as 63.5 for a dacron string ie 4.5 inches less than bow and 64.75 ie 3.25 less than the bow for a D75 string.

The 3.25 I can just about understand as .25 of an inch will not change the brace height very much. But won't 1.5 inches differance make a large differance to brace height.

Thanks Jeff

[Kellog]

Dacron stretches a LOT more than D75 which could be why. However I don't think I've ever brought a pre-made string for my bow so I don't know how long mine is :S

[Russ]

Agreed with Kellog, I think it has to do with the stretch of different materials. When I put my first D-02 string on my bow it was over-braced - but only for the first few ends or so - then it settled down. I just used fewer twists at the beginning, and added more as the string stretched (i.e. over a week or so). It's been stable now for a while but haven't bothered to measure it, but now that it's stretched & "shot-in" I imagine it comes pretty close to Hoyt's recommended length.

[TimGriff6]

Originally Posted by Kellog

However I don't think I've ever brought a pre-made string for my bow so I don't know how long mine is :S

So (assuming you mean that you make your own) how do you decide how long to make the string?

[Kellog]

I do make my own

To decide how long to make a new string I set up the string jig using my current one. It ensures the the string is the same length (or as close as possible) as the one I have been shooting, which makes setting the bracing height on it a quick job. As the string length is nearly there already

[TimGriff6]

Ah, right. So you must use a non-creep material otherwise each string would get a bit longer. I know that different materials stretch under tension and have found a bit of info on that but how do you find out the amount of creep to expect? Is it related to stretch?

[Kellog]

Creep is caused by stretch, as the string stretchs the bracing height "creeps" down.
And tho yes I do use a non-creep material (BCY 8125) it wouldn't matter whether I did or not.
Bracing height is something that (theoretically) should be checked everytime you shoot so you know what it should be. And if its dropped you put more twists into the string. Therefore, even if the string has stretched you'll have enough twists in it that it will be the right length to set up the jig

[reckless]

Originally Posted by Kellog

I do make my own

To decide how long to make a new string I set up the string jig using my current one. It ensures the the string is the same length (or as close as possible) as the one I have been shooting, which makes setting the bracing height on it a quick job. As the string length is nearly there already

personaly i find that useing an old string to measure the lenght for a new string is not quite accurate as you introduce the strethch that has occured in the older string and you also have to make sure that the older string you are useing is fully untwisted.
i find it best to have a mark on the jig for your string lenght. this enables consistant and repeatable strings..

[Kellog]

The jig I use isn't mine, it belongs to the university club; so marking it isn't really an option.

Why would you untwist it? By leaving it twisted you ave it at the correct length? And given I make all my own strings I know the details, like how many strands etc, so I don't need to untwist it to count them or anything. (genuine question, not a snipe.... I just can't find a way of saying it that doesn't sound rude or aggressive!)

[Huffy]

Kellog, would you not need to untwist the old string as the way you describe your method you will end up with a new string with no twists being the same length as the old twisted string. Then when you fit the string (and put some twists in to keep the strands together) it will be shorter.

Sorry if I am missing something in your answers.

Best wishes, Mark