# Dumb question, what does brace height do?



## Eldermike (Mar 24, 2009)

A drawn bow is a D shaped spring with a bent string forming a triangle. The shorter the string the more flex required in the limbs to make the same triangle. The triangle is your draw length. Longer string means less limb flex to achieve the same triangle. The energy is stored in the flexed limb.


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## Viper1 (Aug 21, 2003)

Celtic -

A taller brace height will:

1. Increase draw weight
2. Decrease arrow speed
3. Soften the dynamic spine of the arrow

A shorter brace height will:

1. Decrease draw weight
2. Increase arrow speed
3. Stiffen the dynamic spine of the arrow

Now, that's all well and good, but your bow will have a "sweet" spot based on the arrow you're using, your shooting technique and your tuning ability. That's the brace height you're looking for and that will be trail and error.

Viper1 out.


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## Celtic Dragon (Jan 4, 2009)

Cheers guys.

If my thoughts are right, I'm looking for a 37 - 40lb at 29" (to get to my prefered anchor is 28.5")


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## DwayneR (Feb 23, 2004)

Adding to Vipers list...

BH can also be used to control the slap on your arm. We are not all built the same way... sometimes only a 1/4 of an inch is the difference between being slapped silly and shooting for fun.

BH can be used to control Point of Aim and Gap.

BH can be used to sound (noise) of the bow... 

But most of all, use it for proper tuning and have the above as secondary assets.

Dwayne


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## Viper1 (Aug 21, 2003)

Celtic - 

Not following. Hitting a brick wall means you've hit the bows stack point or you have a physical anomaly that stops you from going back any farther. In other words, draw weight/brace height should have no effect on your ability to anchor/extend.

The TALLER brace height should make the the bow a few pounds HEAVIER and reach its stack point (if that's what's happening) earlier.

Viper1 out.


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## DwayneR (Feb 23, 2004)

> If my thoughts are right, I'm looking for a 37 - 40lb at 29" (to get to my prefered anchor is 28.5")


 You probably will not find such a bow...

Look for a bow that is marked 35 @ 28.

Most all bows are marked X # @ 28 meaning X pounds at 28inches.

add/sub about 2 pounds per inch difference.

Thus, a 35#28" will be about 36 pounds at your 28.5 inch DL.

Also, if 28.5 is your compound DL, then you may find out you will drop about 1" or so when you switch to a recurve. 


Dwayne


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## DwayneR (Feb 23, 2004)

Viper, it almost sounds like a homemade bow, and he has hit a high stacking situation.

Celtic, how many pounds is this bow?


Dwayne


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## Celtic Dragon (Jan 4, 2009)

Dwayne, its being custom made so is possible. Thats not my compound draw either, thats 27.5, but I draw recurve further back.


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## Celtic Dragon (Jan 4, 2009)

Viper1 said:


> Celtic -
> 
> Not following. Hitting a brick wall means you've hit the bows stack point or you have a physical anomaly that stops you from going back any farther. In other words, draw weight/brace height should have no effect on your ability to anchor/extend.
> 
> ...



Stack point would fit perfectly, but its happening with the lower BH, with the taller BH I can get to my prefered anchor, with the lower 1, I hit the stack.

Dwayne to answer you, its a Samick SHB not home made.


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## alanraw (Feb 18, 2005)

Celtic Dragon said:


> Cheers guys.
> 
> If my thoughts are right, I'm looking for a 37 - 40lb at 29" (to get to my prefered anchor is 28.5")


Your brace height is going to be the distance between the string and the bow, usually measured from either the back of the shelf to the string or the throat of the grip to the string


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## Viper1 (Aug 21, 2003)

Celtic - 



> Stack point would fit perfectly, but its happening with the lower BH, with the taller BH I can get to my prefered anchor, with the lower 1, I hit the stack.


Not by the laws of Physics. something else is going on. The lower brace height should be lighter, possibly smoother and stack later. 

If you have a scale, measure the weight in 1" increments from 26 to 30" with both brace heights and see what happens.

Viper1 out.


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## Celtic Dragon (Jan 4, 2009)

Then I have no idea, unless my shoulder is goosed.

I do know with the taller BH, I pull 37lbs.


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## Celtic Dragon (Jan 4, 2009)

Did a quick experiment last night. Low BH is 8" an higher is 8.5"

With the taller BH I can get back to my prefered anchor and my bow arm is straight, its also easier to pull.

Alarmingly, the limb tips are past vertical when at full draw!!!!. The new bow will be 62" where as this 1 is 54"


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## alanraw (Feb 18, 2005)

Celtic Dragon said:


> Did a quick experiment last night. Low BH is 8" an higher is 8.5"
> 
> With the taller BH I can get back to my prefered anchor and my bow arm is straight, its also easier to pull.
> 
> Alarmingly, the limb tips are past vertical when at full draw!!!!. The new bow will be 62" where as this 1 is 54"


A longer bow will typically be more forgiving. Also easier to draw and shoot with less or no finger pinch. Wise choice in going longer


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## DGZ (May 11, 2013)

I just found this old post, but I have to say I'm a bit confused. With a bow with a shorter brace height (i.e., longer string), wouldn't the bow be drawn back further, thereby increasing the amount of stored energy? Maybe that's why the arrow speed would increase, but why would the draw weight be less, instead of more? (Doesn't screwing in the limb bolts also decrease the brace height, but that definitely increases the draw weight, doesn't it?)

The reason I'm curious is that I've noticed that I've needed to lower my sight over time. The only equipment thing I can imagine that would cause that is my string stretching, which would lower the brace height. But then I thought that would make my arrows go higher, not lower. 

Thanks in advance for any clarifications you can provide.


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## Viper1 (Aug 21, 2003)

D - 

Yes, the lower brace height will increase the power stroke (push the arrow for a longer distance) and make it go faster.
However the taller brace will shorten the power stroke and (push the arrow for less distance) and make it go slower.

BUT .. the taller brace height also make the limbs bend more at any draw length, so the weight will be more and vice versa. 
Seem counter intuitive, but that's the way it works. 

However, with modern bows, especially ILF rigs, those differences are minor and in some cases hard to detect. 

Viper1 out.


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## Hank D Thoreau (Dec 9, 2008)

Except that it is energy that counts, not how long you push the arrow. It's like pushing a car. I can push a longer distance with a little energy, or a shorter distance with a lot of energy. The energy I put into the car will tell me how far it will go when I stop pushing.

I have done some brace height energy tests that are counter to the counter intuitive rules of thumb. My tests were with super recurves which may differ from the rules normally experienced with conventional recurve bows. 

I need to redo the tests with more bow configurations.


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## Hank D Thoreau (Dec 9, 2008)

Here are some charts from tests I did a few years back. Click on the image to increase the size of the pictures.

The onset of stacking is best shown with the first derivative of the draw force curve (aka, the smoothness curve). Notice that lower brace heights are stacking later as suggested by Viper.


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## survivalistd (Jun 26, 2017)

Great charts....thx for posting

Sent from my SM-N950U using Tapatalk


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## lentuk (Oct 21, 2012)

When building a warf, how does one know where to start with brace height?


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## Stash (Jun 1, 2002)

Suggest 13% of the bow length, with a minimum of 8” as a starting point.


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## lentuk (Oct 21, 2012)

Great, it looks like its going to be a 64" bow so 8.32 inch brace height to start, thank you.


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## Corene1 (Apr 27, 2014)

So on a ILF type bow or a 3 piece takedown bow how does the limb pocket angle or amount of deflex in a given riser affect starting brace height?


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