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longer axle to axle reach distance easier?

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anyone know why a long axle to axle bow will have a higher sight elevation setting for a given distance shot...noticed out at long range shots for sure.

Marcus from archeryforum said he noticed as well and was going to investigate why, maybe you talk about this a bit if you have anything else to share,

thanks
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if you are comparing equal speeds then yes the longer A-A will because the string angle will put the peep at a higher position at full draw from the arrow.
 

· Francis
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Discussion Starter · #3 ·
Hi Sean,

Thats what i was thinking at first, but when you picture it a little deeper, its the vertical height of the peep from that matters, and this will be the same no matter the axle length of the bow, so nope I dont think it could be this,

I am now wondering if it has something to do with the difference in distance between the peep and the sight pin, a shorter bow you have to slide the peep up the string more, which at fulldraw would make it closer to the sight pin as compared to how you would have the peep adjusted on a longer axle bow.............but if this does make an impact, the results should be opposite of how I would expect it to be .......
 

· Registered
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Hi Sean,

Thats what i was thinking at first, but when you picture it a little deeper, its the vertical height of the peep from that matters, and this will be the same no matter the axle length of the bow, so nope I dont think it could be this,

I am now wondering if it has something to do with the difference in distance between the peep and the sight pin, a shorter bow you have to slide the peep up the string more, which at fulldraw would make it closer to the sight pin as compared to how you would have the peep adjusted on a longer axle bow.............but if this does make an impact, the results should be opposite of how I would expect it to be .......

You're both right. The peep height and distance from the sight pin will change the elavation position as well as pin gap,
 

· aka former "treeslayer"
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but the peep height doesnt change........

Can you explain what the change in peep to sight distance does, I am having trouble picturing what happens and why...
The distance from your eye to the peep will affect what size peep you need to center the housing of the sight in the peep(for accuracy). The further from your eye the peep is the bigger peep you need.

The distance from the peep to the sight will affect this as well. The closer the peep is to the sight the bigger peep you need.

The only thing that should affect where the sight gets positioned would be peep height or anchor point.

An example, Hoyt Vulcan is 33" ATA and I used a 1/4" peep with the sharp string angle.
I switched to the Vectrix XL at 36"ATA and had to drop to 3/16" peep. Used the same sight on both bows, and the same anchor point. The only thing that changed between the bows was the string angle. There was no noticeable difference on sight mounting height.
 

· Registered
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but the peep height doesnt change........

Can you explain what the change in peep to sight distance does, I am having trouble picturing what happens and why...
actually thinking about it, it would change slightly. take into account its just a triangle, and for instance use your arrow as the triangle's base. trig here, string length from arrow to peep = a, height to arrow = b, x = angle of string to arrow in degrees

sin x = b/a
(sin x) * a = b

at rest, x = 90º,
b = (sin 90º) * a
b = a

at full draw, assume 60º angle for simplicity of math
b = (sin 60º) * a
b = 0.866 a

and so on... but it does show that peep height would change less with a longer ATA, as the angle change would be less than a short ATA.

Although i'm not sure how much of an effect that would have considering the distances...
 

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At full draw, the peep to arrow shaft measurement is longer on a longer ATA bow because of less string angle!

On the short ATA bow, the string angle causes the peep to arrow shaft measurement to be shorter!

Even though it is a small amount between the two, it is enough to cause the sight picture variation you are seeing.

And remember, the static peep sight measurement can be identical and still have different peep to arrow shaft differences at full draw.:)
 

· Banned
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sean is right,these new super short bows have ridiculous string angles at draw,particularly with longer draw lengths.
 
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