Why does the Bracing height change ?

[Robert]

Just wondered if anyone could nail this one down for me.
When I setup my bow I use my string which has the same number of twists in it from when the bow was taken down, since the ends have been held together. I check the bracing height after assembling the bow and "seating" the limbs by pinging the bowstring. It is at its normal value (23cm). After approximately 2doz arrows If it is checked again it has fallen to 22cm.

I add twists to the (fastflight, shot in) string to bring it back to 23cm and continue. The string is carefully removed at the end of shooting and the ends are secured together.

The next time the string is used its at 23cm initially but almost always I end up adding twists after a while.

1. Is this normal - I'm getting worried a bit as the string is getting more twists every time its shot.

2. Would a new string sort this out or is something else more likely to be at fault.

Thanks in advance.

Robert

[Schme1440]

Well if the string is quite old then it may have lost some of its strength and is stretching again. That is a possibility.

IMO get a new string but Im sure some one will have a full on scientific explination for this and will help more than I was able to.

[buzz lite beer]

just about all materials in a bow, stretch or are affected by temperature and moisture to some degree even synthetic foam cored limbs aren't immune, elongation of the strands in the bow string, wax dispersing along length of string, limbs relaxing, a good piece of advise given to me was to put my bow in my shooting line tent keeping it in the shade, a whole centimeter is a lot of settlement, If you unwind your string and pull the loops tight are there any loose strands amongst them, if so discard string. I like to set my gear up as soon as possible, then just before commencing sighters/shooting check settings again and adjust if required

[moley101]

One of the main culprits for changing brace height will be 'stretch' in the string. It isn't the actually bow string material itself that stretches, more the wax in the string enabling the strands to resettle. I would suggest you use a piece of kitchen paper or serving, and give your string a good rub to remove excess wax.
If you notice you have more 'stretch' in warm indoor halls or outdoors in the sunshine, rather than cold halls or outside in the cold, then this should help it.
Other than that, try a new string to see if you have the smae problems.

You may have hidden broken strands I used to shoot fastflight and it stopped stretching much after a few hundred arrows.Try a new string, shoot it in and see if the problem goes away providing that you don't change anything else it should be reasonably stable

[john heff]

Would it be possible for you to leave your bow strung after shooting it one day until after the next time you shoot it, and then measure the BH after you've finished shooting it the second day? If BH remains the same measurement then I would think the string is good. - John

[Robert]

Well I left it strung in my nice cosy lounge for a couple of hours and the BH dropped by a couple of mm , Numpty is going to make me a new string (and I'm going to learn !) and we'll see how it goes. The worst that can happen is I learn a new skill and get a new string, but hopefully I have discovered that a few pounds on a string is the best value upgrade you can get.

Thanks for all your replies, the is on me.

[TJ Mason]

(Bit late to this thread, but...)

This happened to me when I got back into archery 3 years ago. I bought a Fast Flight string from Top Tox, and it wouldn't stop stretching. After a while I bought another from them, and that wouldn't stop stretching either. Then I bought one from Aardvark, and that was absolutely fine. The ones I've since made for myself have also been fine. So I'd suspect the build quality of your string.

[exziit]

this happened to me about a week ago, my bracing height is 8 3/4 but for some reason it changed to 8 1/2 without unstringing the bow, the string was really old and it stretched again i guess, i always though strings would just stretch when theyre new...

[Kae]

Originally Posted by exziit

this happened to me about a week ago, my bracing height is 8 3/4 but for some reason it changed to 8 1/2 without unstringing the bow, the string was really old and it stretched again i guess, i always though strings would just stretch when theyre new...

As the string material gets older it can start to break down. The modern string materials don't tend to snap anymore, they just lose consistency and seem to never stop stretching. Thats why its a good idea to replace recurve strings at least once a year, whether you it looks like it needs it or not.

Kae.