I read on Easton's web site that decreasing the brace height of a recurve bow will have the effect of increasing the arrow's spine; and vice versa. Can anyone explain how this works and, for example, how much approximate spine increase would result from decreasing the bow's brace height by 1".

It will differ from bow to bow, can't explain how it works. But from my experience, especially with recurves, I set the brace height to where the bow is the quietest and arrow flight is good. If you move it an inch from there, especially to the lower side you probably won't get good arrow flight from any arrow. 1" is a ginormous change in brace! I follow the bowyer's recommended brace and make minor tweaks from there.

If you start out with a BH that is quiet, an inch is really a lot. Probably won't be so quiet when your done.

I just had a LWer friend call me up and ask a related question. My answer was not thought through and I had to go back and forth, ended up saying I was right the first time.

He said his bare and fletched were impacting together. Broadheads were also impacting with field points - the key to tuning is www.acsbows.com/bowtuning.html click on 'download printable version'. "But my bare shaft is not flying perfect. I'm getting nock kick out to the right. Should I had more weight?"

I told him depending on the amount of kick out, since his bare and fletched were impacting together, he could probably get the bare shaft straight with a couple of string twists 2 to 5.

Kick out to the right is stiff. If you add string twists you're increasing poundage. Trial and error is the only way to tell how many.

I'm wondering how it worked???

Bowmania

read this from Rick Barbee http://discussions.texasbowhunter.com/forums/showthread.php?t=646137

Just remember it's not that the arrow's spine is actually made to be stiffer. Rather it is the arrow's behavior.

What is going on, is that tuning is a process where we establish amplitude, frequency and TIMING of the arrow's flex and oscillations that are established upon release. We do this to get the arrow past the riser with zero contact.

When we alter brace height we alter the timing of the arrow nock separation from the string. That's pretty much it. Yes, KE storage and delivery efficiency are altered. No doubt. But for purposes of practical application to tuning, that timing issue will will have priority.

Now if we are within "operating range" of brace height, then yes lower brace yields stiffer arrow behavior. However, if we're starting out at some extreme, or have nock fit problems with the arrow nock being too tight, then forget it. Things probably won't follow that guideline. In that case, have fun! :) Been that, done there.

Well worth the read, and thinking.

-Bones

Lowering brace on a bow that is Not cut past center pushes the tip of your arrow left giving the same effect as having a bow that no longer cut as far in. Thus making your arrow too stiff for the lesser center cut. Put an arrow on your bow and look how far left your tip is, then drop the brace 1 inch and try it again. You'll see ur tip is much farther left giving the effect of a stiffer shaft.

Understand the difference between static spine and dynamic spine, then it will make sense.

1" of brace height is equal to a corresponding 1" of draw length.

If you decrease brace height 1" you increase draw length 1". If you increase brace height 1" you decrease draw length 1".

Lowering brace height does indeed move the arrow point left of center. It's because there's an extra 1" or whatever the measurement you lowered it, sticking out in front of the bow.

However, how far the arrow is from the center of the limb is irrelevant as it pertains to arrow flight and dynamic spine in the grand scheme of things. You shouldn't be aiming the center of the limb. You should be aiming the center of the arrow from the string to the point.

Trying to aim using the center of the limb is what causes folks to have big time problems choosing arrow spine.

Power stroke IS draw length. How far the string travels from full draw to brace height is draw length. It IS NOT arrow length, but it id draw length.

That's another popular archery misconception.

That's correct. However, it doesn't change the AMO measurement.

The reason it's called draw length, is because it's the distance you draw the string. Not how long the arrow is. You can take that same 28.5" arrow and cut 3" off of it so it draws up on to the arrow shelf. You are still only going to draw the bow (move the string) 20.5" unless you change your anchor/sighting reference.

So, if you have a bow braced at 8" lets say and you move the string to 26.25" from the pivot point of the grip, to your full draw position. That's the AMO standard. 26.25" from the pivot point of the grip. You moved the string (drew the bow) 18.25".

Now, if you raise the brace height 1". and you draw the string to the same anchor, you move the string (draw the bow) 17.25".

Conversely, if you lower the brace height 1", and you draw the string to the same anchor, you will have increased your draw length (the distance you drew the string) by 1" to 19.25".

Draw length is actually the distance the string travels from brace to anchor, and from anchor to brace. Same as the power stroke.

But like I said, that's not the same as arrow length.

The measuring arrow length to the back of the bow is simply easier for folks to work with.

Ultimately the width of the shelf has a big impact on arrow length. However it doesn't change draw length.

That's why if you are using arrows that are net length, so that you can have the arrow bump the back of the bow you measure from the spot you hold the bow when you draw it, and add the width of the shelf. That the BOP measurement for your arrows.

Frank is incorrect on this one.

Nope....remember we are talking about how far the string moves from brace, not how long the arrow is.

All you have to do is go get a bow, string it up, and start playing with the brace heigh. Then start measureing string travel at each different brace height.

Draw length is not the same as power stroke. Never has been.

JusPassin, draw length was/is power stroke as I said before. ARROW LENGTH is NOT really draw length.

That measurement came about with the creation of AMO. I'm not sating it's a bad thing, it's just what it is.

A 28" draw length is defined by AMO as moving the string 26.25" from the deepest part of the grip. Wil a standard (as adopted by AMO ) 1.75" distance from the pivot point, to the front of the shelf, that would require a 28" arrow.

You aren't drawing the bow 28". You are drawing the bow 26.25" minus the brace height.

Bowmania, 3 twist to shorten the string, was 1/8" increase in brace height, bare shaft straightened right up, and already quiet bow was quieter. Thanks for letting me bounce my thoughts off of you. Randy

Even back in the 50's and 60's power stroke was the number of inches the string pushed the arrow, not how long your arms were and how the bow was designed and how long the string was or all the other variables.

Not where I come from it wasn't. That's why folks measured true draw length to the center of the riser, the plunger hole, or a point just above the deepest part of the grip.

Then they added to that length to arrive at an acceptable arrow length.

I mean this can be argued all day long, and you can try and justify it any way one wants to.

But draw length is the length that you draw the bow. That's why it's called draw length.

If one prefers the term "power stroke" that's great. But just know that the power stroke can't be longer than then the distance you draw the bow.

Whenever I change brace height I change my powerstroke but my draw length stays the same.when you change brace it will either put the string closer to the bow or further away (powerstroke).draw stays the same...

"Whenever I change brace height I change my powerstroke but my draw length stays the same.when you change brace it will either put the string closer to the bow or further away (powerstroke).draw stays the same..."

This makes sense to me.

exactly Jeff

Well guys, you have the way you learned recently, I have the way I learned long ago, and they are different.

However, the power stroke is EXACTLY the same measurement as the length you draw the bow, the draw length. Always has been.

You guys are talking arrow length, not how far you are actually drawing or moving the string. Your arrow length can stay the same, and you can actually draw the bow (increasing draw length) by 3" by lowering the brace height a corresponding amount. And yes, that's an exaggerated example.

Spine not just about your aim. If you lower the brace too much and put the arrow point too far left it takes a weaker arrow in order to have enough flex to go around the riser and achieve good flight.

As for draw length why not just keep it simple so people don't have fits buying a bow at the right weight for their draw length. No one uses amo any longer and most people didn't even back then. When I had my archery shop in the 80's only one compound manufacturer used amo for draw length. Jennings used what they called true draw as their measurement. Which measured draw length to the berger button hole which was directly above the deepest part of the grip. Everyone else measured to the back of the sight window.

Oh, and the arrow points farther left when you lower brace because the string is in the center of the bow and most stickbows are not cut past center so on some bows if you lower the brace till the string touches the bow the arrow would be pointing 90 degrees left.

I am sorry fdp you are mistaken. Look at any written material such as Easton's How to Tune book on how to measure your draw length. It is from roughly the low point of the grip/plunger hole + 1 1/4" to your anchor point. You can measure your draw length pretty close from your chest to the tip of your outstretched fingers. I have a draw check bow like all shops used to have. It has a captured arrow marked off in inches. It makes not one bit of difference what the brace height is. It will still measure DRAW LENGTH exactly the same. You can measure draw length with an unbraced bow. Brace height changes the power stroke it does not change the length of a person's arms. It is a common mistake to interchange the terms draw length and power stroke. Draw length is the individual. Brace height is the bow. No big deal but don't want to confuse folks.Bows have brace heights and power strokes. People have draw lengths. Hope that clears it up. What is your draw length? Mine is 29 1/2 with any bow at any brace height. Ken

I'm trying to remember if anyone ever answered the OPs original question, before the debate on draw length vs power stroke took over! LOL

fdp ....amazing!...lol

You know you are right. They are connected though. O.K. If you lengthen the power stroke/lower the brace height it may need a little stiffer spine. Although that increases the angle of the triangle from bow string to arrow rest(angling the arrow farther to the left) if it is not cut to center. That would call for a little weaker spine to flex around the riser. Soooo call it a wash. If you are on the extreme edge of an acceptable tune it could necessitate a change in spine. It is best to tune for the middle so a little change like a couple of twist in the bow string does not throw you out of tune. Temperature,getting wet,how long the bow has been strung can slightly alter the brace height. You don't want to be on the very edge, that close to being out of tune. Tune brace height for smooth quiet bow first. Use spine/point weight or strike plate if necessary, to tune for flight. Hope that helps. >>>----> Ken

Thank all of you for your input. I've learned a lot. Bill Hofstetter

If my bow is braced at 8" and if I will decrease it to 4" does my drawlength increase for 4" ...? Do I gain more poundage cause of more drawlength ... hahahaha ;-)

FDP couldn't be more wrong , GLF couldn't be more right

There are a lot of terms used to describe various aspects of any activity a person pursues. It is fairly often that the words used to identify those terms are not necessarily descriptively accurate. I think all this arguing about power stroke and draw length is just a matter of the differences in the understanding of the terms being used.

I also think that there has always been a difference between draw stoke and draw length. Draw stroke equals power stroke and I believe that is what FDP is actually talking about. Maybe I misunderstand him.

Draw length for as long as I can remember (at least 50 years) has always been measured in relation to the pivot point of the bow. And this is just a definition of a term. The term itself is not necessarily accurately descriptive.

Well Nordland, you will be drawing the bow (moving the string) 4 more inches to get it to your anchor point, so you decide.

Any slo mo camera will show a degree of string travel past brace-less so with new string material. Does this get added into power stroke? If f so how is it determined? Or is it ignored in this way of viewing it?

fdp, a guy shoots a 30 inch arrow. His power stroke is say 20 and I ask him and 90% of the people here to describe WHAT his draw length is, they're going to say the distance from the back of the bow (closest to the tip of arrow) to the nock at anchor.

While I agree with you and JustPassin, if the power stroke and draw length are the same, there's no need for one of the terms.

Bowmania

Just curious fdp. I read every one of your posts. Did you read mine? There were only 2 this being the third.Thanks.>>>----> Ken

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