String stretching and twisting.

[Boo]

As you shorten the string you effectively pull the limbs back more raising the poundage at full draw. There are diminishing returns as you shorten the stroke while at the same time raising the bows draw weight.

[Kegbelly]

Makes sense, Boo, never thought of it that way. Thanks!

[Pydpiper]

I would think that would work the other way.
As you shorten the string you are decreasing the powerstroke, thus increasing the poundage at full draw?
Having a hard time picturing it.
Decreasing the powerstroke (shortening the string)would result in a slower arrow combined with increased pressure on the limbs?
I can see no benefit in that.
It would come down to whether the bow likes to have the speed derived from the initial snap of the limbs due to the shorter powerstroke, or if the bow prefers the full movement of the limbs, lengthening how long the string is in contact with the arrow as they try to return to their resting position.
Some arrow combinations may prefer a longer powerstroke, but it would make no sense to me to not utilize the full power of the limbs.
I suppose that's why there is a "happy medium" in a brace height, or a "sweet spot" as some call it.

[Boo]

I'm a little confused by one thing... I've put new strings on my bow a couple times now, and with a new string I start out with a higher brace height than I normally shoot, which causes the the POI to be higher, then as the string settles in and brace height gradually drops, the POI gradually drops as well. But with a lower brace height you supposedly pick up a few fps so shouldn't the arrow hit higher? More fps = flatter trajectory = higher POI? Seems contradictory, you'd think as brace height drops and arrows pick up speed the POI would raise, not drop.

Another factor that just came to mind is that there is a measurable speed lose on some new strings (not mine). When a string is settling in there is significant amount of energy wasted on the elastic nature of a string that has not settled in.

[Kegbelly]

I would think that would work the other way.
As you shorten the string you are decreasing the powerstroke, thus increasing the poundage at full draw?
Having a hard time picturing it.
Decreasing the powerstroke (shortening the string)would result in a slower arrow combined with increased pressure on the limbs?

Both explanations seem to make sense. By shortening the string you're effectively adding some preload to the limbs by pulling them back a little, which would add some extra poundage both at rest and at full draw because you're still pulling the limbs that much farther back, but it shortens the overall power stroke by whatever amount you raise brace height. I've noticed with a higher brace height the bow shoots a little smoother, yet it feels slower, but hits higher? Thats the part that makes me scratch my head, just seems contradictory. Oh well, find you're sweet spot and shoot it!

[ELLIS]

Another factor that just came to mind is that there is a measurable speed lose on some new strings (not mine). When a string is settling in there is significant amount of energy wasted on the elastic nature of a string that has not settled in.

Don,

Your remark of "elastic nature of a string that has not settled in" caught my eye.

I am rotating four Excalibur Flemish Dyna-Flight Strings that have been reserved several times to shoot 3D tournaments with. Sometimes if the serving separates mid-tournament and I change the string on course. Up until now I blame flyers on myself and not my equipment. A question has crossed my mid due to your statement. If I put on a reserved string that has been sitting for a few months could it have changed its elastic nature not being under tension on the bow? If this is the case would the speed of the bow change even if the same brace height is maintained (one inch) resulting in a bad shot?

Another question, one of my son's is giving a Excalibur Flemish Dyna-Flight String for Christmas. Could you guesstimate now many shots will I have to take with my Equinox to settle it in?

Cheers,

Bill

[Boo]

Bill, there are so many variables. If you're talking about the target accuracy I know you're looking for but I'll guess well over 100 shots. For hunting much less.
I am familiar with Danny's string but not intimately so these are just guesses.
Prestretching will make all the difference to you.

[Pydpiper]

My bow works the opposite, my POI increases as the string creeps.
I keep my spare strings under tension, always wondered if letting them sit will require a new break in period. I used to keep it in my jig, but now that we are up to a half dozen Excaliburs in the house I had to rethink my design, due to no two strings being the exact same length.
I made a unit that resembles a jig, it will hold six strings, each under pressure from the jig, but on one end I have a trampoline spring to hold one end, so each string gets even and consistent pressure.
I used to hang them, with a weight to apply pressure, but this new jig is far more efficient.
If you use a weight to keep pressure on a hanging string, be sure to secure it, or it will want to spin in the direction of the string twists, and make a string useless in a matter of minutes.
Bill, yes, a string that has once been broken in will need a new break in period, but the break in happens way faster the second time.

[Kegbelly]

That's interesting your POI shifts just the opposite. I've been shooting in a new string over the past few days, my POI definitely drops as the string moves and brace height drops. I just hunt, not competetive shooting, so I keep a couple old broken-in spares in a little gear bag attached to my stock. I figured it would just be a matter of restringing, setting brace height to the desired level, and go, didnt know an old string would require another break-in phase. Learned something else today.

[awshucks]

my POI definitely drops as the string moves and brace height drops.

Happened that way on every Excal I've owned.......

[Kegbelly]

my POI definitely drops as the string moves and brace height drops.

Happened that way on every Excal I've owned.......

Whew, thought I was losing it!

[Kegbelly]

...I'm no marksman, but I think setting your brace height back to your sweet spot on a spare string should be good enough for any hunter. I do recommend shooting the string in before making it a back up. JMHO!

Me either Dan, but I play one in the woods. What you said is what I was thinking, as long as a string has been shot in beforehand, it should be good enough to hunt with if you have to restring in the field. Good to know!

[Pydpiper]

A couple shots on the string will do a lot more to the settling in process than leaving it cocked.
I left a Dacron string cocked for 72 hours, it dropped about 1.5 string widths (new string), 3 shots and dropped almost 2 more.

I guess one would need to specify what the mean when they say "is there a difference?" I measure change with a caliper, both on the string end, as well as the target.
For hunting purposes, there is little change, it should not affect your POI to the point you should be concerned.
But, there IS a difference.
I am no target shooter either, but I love to accumulate data. When a string will need to be broken in after it is removed from a bow, I didn't mean a week, I meant a season, like when most would consider swapping strings.
If we are only talking a few feet per second, or a half inch at target level, then using that principal it would make no difference to randomly click the scope turrets 1 click every now and then, the end result will be the same. Still deer accurate, and an almost non measurable difference, but a difference all the same.

When I seen the question "is there a difference?", I thought it meant they wanted an quantifiable answer, not a "deer accurate" answer.

[Pydpiper]

Yep!
The way I see it, the bow is very well designed, so much so that it will repeat the same thing over and over.
One just has to decide what it is they want it to repeat.

[Limbs and Sticks]

I've got a white string that is close to four yr's old, it's been reserved three times by three different people, the only time my dirty blond gets shot is during hunting season, same speed and BH no changes what so ever, to me once the stretching is done the only thing left is for it to break, I've seen one string width make a little difference on poi. To me there's just a starting point then you figure it out from there, there is no fit all BH each bow has it's own personality.