Byron Ferguson and brace height tuning

[NothingHappenedToday]

Hi all, I just read Byron Ferguson's "Become the Arrow." In it, he recommends decreasing brace height for stiff arrows, and increasing it for weak arrows. This is the exact opposite of everything I've read and seen online and in books. Seeing as how he's such an accurate shot, is he right and everyone else is wrong? Thoughts?

[Orion]

Byron's right. And it coincides with most everything I've read. Reducing the brace height lengthens the power stroke, increasing it reduces the power stroke.  Small changes in brace height are really just for final tuning though.  They don't make a big difference, but the direction of difference is what Byron suggests.

[Cootling]

My personal experience mirrors that of other things you've read. Symptoms of a stiff arrow are resolved by increasing brace height, symptoms of a weak arrow are resolved by decreasing brace... and very slight changes that don't much affect length of the power stroke can make quite a lot of difference.

[Mr. fingers]

opposite

[Caughtandhobble]

I'll I have read the book... If indeed he states that I will have to agree to disagree.

[NothingHappenedToday]

Caughtanhobble it's on page 46

[Greg Owen]

First off, I am no expert but what Byron Ferguson says seems correct to me.  A stiff arrow will be weakened slightly by a longer power stroke which means a reduced brace height. Increasing the brace height would reduce the power stroke and make a weak arrow shaft seem slightly stiffer. Again, I am not an expert just the way my brain thinks.

[Orion]

I should elaborate.  As I noted, these differences are very small.  Increasing the brace height increases the poundage, but it reduces the power stroke.  Which has the greater effect is probably determined by bow design, and it may be a wash.  

Likewise, lowering the brace height decreases the poundage, but increases the power stroke.  Again it may be a wash. Would have to compare force draw curves for the various adjustments on the same bow to know for certain.

Think about it. A change in brace height of 1/8 inch might increase or decrease the draw weight by 1/4# or so.  That's a very small difference.  That's not a difference that most are going to notice, though those who tune to the nth degree say they can tell the difference.

[Greg Owen]

Please explain how changing brace height changes the poundage of a bow?  I see it changes the preload of the limbs, but at a given draw length the limbs are loaded the same regardless of brace height. It is just the power stroke that is changed. And as you said, it is a minor change.  Just trying to learn the physics of the bow here.

[Greg Owen]

Ok after thinking I understand the poundage change (I think).  Basically, changing the brace height changes the string length. A shorter string increases brace height but also loads the limbs more at the given draw length. So the draw wight is increased, but the power stroke is decreased.  Which has greater significance?  This is where I need a chrono to do some testing.

[Caughtandhobble]

The way I see it is all about the angle of the arrows approach. The shorter the brace height the arrow is getting to the shelf faster and heading to the left sooner (right hand shooter). Vise versa for the longer brace height... I hope this makes some sense.  

[highlow]

Please stop. I thought I had this tuning stuff figgered out and now this. Oy vay!  

[Tradcat]

IMHO...Mr. Ferguson is correct

[ChuckC]

Ok, so.... if the tuning of your bow isn't quite right, add or remove twists to your string, which will change the brace height and several other factors about the bow's physics.

That can either change or not change something and everything might be good... or not so good... or we can't tell anyway.

I got it !      

ChuckC

[BWallace10327]

Originally posted by highlow:
Please stop. I thought I had this tuning stuff figgered out and now this. Oy vay!      

That's how I feel- I knew how to coax my arrows to fly right until about 2 minutes ago.

[trasher]

Why is a Bow with 45#@28" slower than with 45#@31"
Because the arrow is accelerated longer at 31".

That means you can shoot stiffer arrows at 31".

OK, this difference is about 3" and the difference by tuning the brace heigh is maybe 0,5" but it also has an impact!

Another comparison.
On my bow 400 spine works perfekt at 31".
When I'm shooting 360 spine the arrow always went to the left because he is to stiff but... when I'm drawing a littlebit more the 31" the arrow went right straigt as he should.

I'm conform with Byron.

[Brock]

actually the longer draw gives you a HIGHER DRAW WEIGHT.....that is the primary reason over drawing increases arrow speed...all things being equal.

for a hunter with consistent draw...the lower braceheight will provide a LONGER power stroke pushing arrow...

two different things...draw length affect vs brace height affect.

[McDave]

Part of the problem here is nomenclature and use of language.  If someone says, "reducing the brace height stiffens the arrow," do they mean that reducing the brace height makes a given arrow shoot as if it had a stiffer spine, or do they mean that reducing the brace height allows you to shoot a stiffer arrow than you could use at the higher brace height?

Same with center shot.  I think I have this one figured out: you need to use an arrow with weaker spine for bows not cut to center shot.  But I've read things that are vague enough to be interpreted either way.

[McDave]

Originally posted by Brock:
actually the longer draw gives you a HIGHER DRAW WEIGHT.....that is the primary reason over drawing increases arrow speed...all things being equal.

for a hunter with consistent draw...the lower braceheight will provide a LONGER power stroke pushing arrow...

two different things...draw length affect vs brace height affect.

I have to disagree with your first statement.  For a given draw length, decreasing brace height results in a lower draw weight, because the bow is less flexed at full draw.  To take it to extremes, imagine drawing a bow strung with the string tight, but not flexing the bow, which would be the ultimate in low brace height.  By the time you got the bow to full draw, the bow might only be flexed to a normal brace height, so would be lower poundage than a bow that starts its draw at normal brace height.

What lower brace height does is increase the power stroke, as you say, which may result in increased arrow velocity, if the energy stored by the increased power stroke more than offsets the energy stored by the slightly higher poundage with the higher brace height.

[Caughtandhobble]

Good topic...

One more thing to think about a shorter brace height has the exact same effect as a harder side plate, leather vs Velcro. When changing the side plate on the shelf from Velcro to leather it will move your arrow to the left (righthand). The brace height has the same effect as how much the bow is center cut only on a smaller scale. Everyone agrees that you can build the side plate out to shoot a lesser spined arrow, right.

The bottom line is if your arrows are spined correctly, the difference in brace height is minimal but it is a difference.

Sorry if I sound opinionated on this matter, what can I say, I'm very passionate about tuning.