posted
I always thought that raising the brace height (ie- from 8 - 8 3/4) would stiffen the spine b/c it caused shorter length of travel for the string, and that lowering the brace height would increase arrow speed and therefore weaken the spine.
Am I correct on all this? Thanks
Posts: 201 | From: Tifton, Ga | Registered: Oct 2007
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posted
Think opposite. I'm not smart enough to explain it, but lowering the b.h. will actually make your arrow shoot stiffer, and raising it will make it weaker.
I learned this from Ken Beck in one of the Black Widow tuning videos. It has held true to all of my bows. Some seem to react to it more than others.
posted
raising the braceheight will weaken the arrow
lowering creates stiffer arrow
there is a valid reason..but im not smart enough to explain it.
-------------------- TGMM Family of the Bow
"There's a race of men that dont fit in, A race that can't stay still; So they break the hearts of kith and kin, And they roam the world at will" Robert Service Posts: 3506 | From: dansville ,michigan | Registered: Jan 2007
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posted
Lower brace heights shoot faster, so go from there. It's like adding draw weight. How can that make your arrow act stiffer?
-------------------- I didn't claw my way to the top of the food chain to eat vegetables! Posts: 3597 | From: Brunswick, Ga | Registered: Mar 2005
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posted
With a lower brace height the draw weight actually drops so the arrow is now stiffer than it should be; i.e. - if your arrow worked fine when the bow had a 50# draw weight and the bow now has (with a lower brace height) a 45# draw weight then the arrow is effectively stiffer than it should be.
One of the reasons that lower brace height adds speed is that the power stroke is longer (the string is pushing the arrow for more time so it is absorbing more energy). You are not getting higher draw weight.
One of the problems with understanding how a bow works is that there are many factors and most folks just look at some of them. Hope this helps.
-------------------- Larry Schwartz, Annapolis, Maryland
Do yourself a favor and join your state bowhunting organization!
Professional Bowhunters Society Traditional Bowhunters of Maryland Maryland Bowhunters Society National Rifle Association Posts: 1600 | From: Annapolis, Maryland | Registered: Mar 2003
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posted
..... remember guys...the arrow spine will stay the same... the change is in the bow braceheight..which will make the arrow "act" weaker or stiffer...
I stole this from oldyork on a previous post..hope this helps...
Short version - Arrow shows too stiff, raise BH. Arrows shows too weak, lower BH.
Long version -
Easton Tuning Guide, 2nd edition
Brace Height For recurve bows, another way of altering arrow spine is with the brace height. By increasing or decreasing the distance from the bowstring to the pivot point of the grip, the dynamic spine of the arrow can be made slightly weaker or stiffer. Increasing brace height will make the arrow shoot weaker, and decreasing brace height will make the arrow shoot stiffer.
Brace height affects arrow spine by increasing or decreasing the amount of energy delivered to the arrow at the moment of release. Raising the brace height (shortening the bowstring) compresses the limbs, increasing stress (prestress or preload) in the limb material. The more preloading of the limbs, the greater the actual bow poundage at full draw. The reverse is true when lowering brace height. A lower brace height (lengthening the bowstring) reduces the prestress in the limbs and reduces bow weight at full draw.
However , raising brace height produces some small loss in arrow velocity as the slight increase in draw weight does not equally compensate for the reduction in the bow's "power stroke". When the power stroke is reduced, the amount of time the arrow stays on the bowstring is also reduced, in turn, decreasing the length of time the arrow has to absorb the bow's energy.
-------------------- TGMM Family of the Bow
"There's a race of men that dont fit in, A race that can't stay still; So they break the hearts of kith and kin, And they roam the world at will" Robert Service Posts: 3506 | From: dansville ,michigan | Registered: Jan 2007
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posted
Thats pretty interesting Larry, I would not of thought that shortening the BH would actually give you more speed. You would think a heavier draw would.
Interesting. I learned something today.
-------------------- Maryland Bowhunters Society Posts: 122 | From: Carroll Co. Maryland | Registered: Mar 2009
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quote:With a lower brace height the draw weight actually drops
Exactly what I was about to say.
**Sorry, Jacobsladder. You posted while I was typing.** I didnt mean to repeat your info.
Super low brace heights will result is lower lbs at the same draw but raising the brace height dramatically INCREASES the draw weight.
With an already further back starting point, the limbs react the same to as they would to a longer draw (but will have a shorter power stroke).
Find the balance of quiet (higher brace height)and speed (lower brace height) and, at least IMHO, you've found the best brace height for most preferences.
I prefer quiet over everything else and set my brace heights accordingly if I have to choose between the two.
This isn't a guess on the weight thing, I've put several on mine on my scale and it holds true.
The change is not DRASTIC but 10 percent of the bow's labeled poundage is about how much mine will change in poundage from pretty high to pretty low brace heights.
Im sure the limb design, material, age, length etc all come into play when considering such on any particular bow so this is only a "rule of thumb" that has worked for me and is not carved in stone.
I can change my brace height on my "43lb" Super K and get 41 lbs and 46 lbs at both extremes of brace height (at 28 inches of draw on the scale)which is a bit OVER 10 percent of the draw weight, in difference.
Picking the right arrow for your desired brace height would seem, to me, to be the right choice but other methods will work with changes in speed or noise resulting that may not be what you find to be what you want.
A couple pounds either way isnt much to give you much of anything by draw weight ALONE, but does exist.
God Bless
-------------------- "Beauty is in the eye of the BOWholder" God Bless!! Posts: 764 | From: Indiana | Registered: Jun 2009
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posted
slowbowke...no problem bud.... i was just trying to help folks make sense of this...it is fairly confusing....
-------------------- TGMM Family of the Bow
"There's a race of men that dont fit in, A race that can't stay still; So they break the hearts of kith and kin, And they roam the world at will" Robert Service Posts: 3506 | From: dansville ,michigan | Registered: Jan 2007
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posted
I approach this with a fundamental outlook; I could give a rat's patoot about any such information, other than to refer to it when I'm old and need some nonsense to blather about in the old folks home.
It's amazing how we can delve into the intellectual side of physics, biomechanics, and other such stuff, and then can't hit a target at 17.3 yards on a regular basis.
Now, of course I'm old and particularly stodgy about my sport of simple archery. I like the fact that I don't have to think much any more and still get perfect flight from any bow I own without using quantum physics, or even elementary math.
You see, we figured it out through trial and error, and knowing why it worked would have taken all the fun out of our mindless escapades. Archery needs mindless escapades, and I will not have people around me using their cerebrums unnecessarily. It just don't seem right when we can be doing things more socially redeeming.
Now....what was the question again????
Posts: 5075 | Registered: Mar 2003
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posted
I'm glad I read this post. Don't know where I got the info, but I've been doing things backwards, i.e., trying to stiffen spine by raising the brace height, lowering to weaken it. No wonder I wrestle so much with my tuning!
posted
Oh....just one more thing, if an inch of brace height, either way, sends your arrow tuning into oblivion, you are dancing on the line of dimishing returns with the spine of that arrow. A well tuned arrow should tolerate a lot of dynamics from the bow without being unduly affected.
Posts: 5075 | Registered: Mar 2003
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posted
What George said,,, and said well..I think!!!!
-------------------- In the beginner's mind there are many possibilities. In the expert's there are few...So the most difficult thing is always to keep your beginner's mind...This is also the real secret of the arts: always be a beginner. Shunryu Suzuki Posts: 9326 | From: tribes hill , new york | Registered: Jan 2008
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