Who Pre stretches their backup

Crossbow Hunting

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sumner4991
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Joined: Thu Oct 19, 2006 12:16 pm

Re: Who Pre stretches their backup

Post by sumner4991 »

Pre-stretching is not a requirement to get the same POI as a stretched string.

You will get the same POI if you use the idential string and same brace height.

However, if you do not pre-stretch the string, then you will need to maintain it more closely while hunting. Your brace height could change slightly when it's cocked during your hunting hours(depends on who made your string and the type of string).

I have shot my backup strings . . .first thing I did when I got a new string was shoot it at least 50 shots.
I'd rather wear out than rust out.
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Hi5
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Re: Who Pre stretches their backup

Post by Hi5 »

I understand the idea of pre-stretching.

However, doesn't a string "relax" after the tension is removed? Doesn't a string that has been prestretched shorten again after it has been removed from the bow? Does it make a difference how long after prestretching and removal the string has been stored?

String makers, what's your verdict?
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Dash
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Location: Australia

Re: Who Pre stretches their backup

Post by Dash »

Hi5 wrote:I understand the idea of pre-stretching.

However, doesn't a string "relax" after the tension is removed? Doesn't a string that has been prestretched shorten again after it has been removed from the bow? Does it make a difference how long after prestretching and removal the string has been stored?

String makers, what's your verdict?
Your right that maybe its not as good as leaving it ready on a jig, but generally that's not a practical option for most people. Even so, a prestretched string will creep less.
For competitions I made a "portable" tube stretcher. A week before a comp, I take my string off the bow while keeping the same twists in it, then kept it under medium tension on a 1"diameter metal tube that I modified to be a basic stretcher. In a comp where 1 or 2 bad shots can mean winning or losing, I wanted to be 100% sure POI will be within an inch for the duration of a comp regardless of a string change. I'm a little OCD when it comes to getting things as perfect as possible, but I've tested this method and its spot on.
For most people doing hunting only, this is over the top, considering without shooting a lot, brace height shouldn't change quick , plus the small effect on a very large target like deer. But during a 120 shot comp, changing to an unstretched & unheated string could send you out of brace height easily in very hot weather here.
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8ptbuk
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Re: Who Pre stretches their backup

Post by 8ptbuk »

In my opion Endless loop strings made with Premium Materials and a high strand count stretch very little . What stretching they do is within the first 20 shots . The factory strings made with D97 dont seem like they ever settle down . JMHO :D
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colouredchameleon
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Re: Who Pre stretches their backup

Post by colouredchameleon »

From a hunting point of view under hunting conditions as I see it if you need to change a string on go the replacement string when first put on is usually put immediately into a loaded position for hours.
So a non-conditioned pre stretched string could have unpredictable environmental influences placed upon it such as temperature.
The result of which could be stretch from the load, which could result in changes to string length / brace height resulting in unforeseen changes to what you believed was your established POI.

The question I have is has any body, which I would think a string makers or a competive shooter might have done to better understand their product or equipment tried the following experiment.

1. Measured the actual length of a new string (both Flemish and Factory supplied). Recorded its actual brace height when first installed.
2. Then cock it placing it under load in the firing position on a crossbow such as the Equinox or Matrix for 8 to 9 hours.
“No Shooting” ( under both high and low ambient temperatures )

3. Then UN cock it measure the brace height again and then completely remove the string and measure its length and compare.
4. Then let the string relax for days or hours to see if it’s length retracts back closer to the original length.


Then shoot the string 20 to 40 times to condition it.
( ie: pre stretch as this tread suggests).

Then repeat steps ( 2, 3, 4, ).
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Dash
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Location: Australia

Re: Who Pre stretches their backup

Post by Dash »

I see what you mean. You can't really measure the string accurately off the bow without some tension, better to compare under the bow tension which is consistent. I haven't measured the difference in creep as you've explained, but it would definitely be relative to temperature in your area, warmer weather more severe creep. It doesn't go back to the original length under bow tension, but there may be a small bit of movement initially when you first reinstall it on the bow.
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