determining Brace Height

[Mjl834]

I'm wondering how professional and amature bowyers determine the brace height for their bows.  Are there standard brace height measurements that are used for the various lengths and styles of bows for example a 70" longbow or a 64" recurve? Many bowyers suggest a range for example 7.5-8.5 inches. How do they come up with those numbers? I've looked around on the internet and have come across a blog post on Lancaster Archry site that has a chart for recurves.

     

And another article on 3Rivers site that says modern longbows are braced at 7" and recurves 7-9".

I'm relatively new to archery and am curious.

Thanks

[Eric Krewson]

Back about 20 years ago when I shot recurves I would shot the bow at a low brace height with my intended arrow setup.

 At first the bow would shoot with a whack, be noisy and the limbs would reverberate after the shot. I would gradually raise the brace height until the bow noise would change to a light "putt" with no limb vibration and would shoot silky smooth.

I would measure this brace height and use it for as long as I owned the bow.

I wrote an article for TBM in Aug of 94 about my bow tuning process.

[Mjl834]

Thanks for the reply.  I understand how and why to fine tune the brace height for a particular bow.  My question is, for a new bow or design that has never been strung before, how does a person determine the rough brace height.  I found a document produced by Archery Australia Inc. Coaching and Standards Committee that suggests to take the over all length of the bow and divide that by 8 to find the rough brace height. Then you'd have to fine tune it from there. Is this an accepted method? Industry standard?

Thanks

[Roy from Pa]

7.5 would be a good starting point. Then do as Eric suggests..

[Mjl834]

For example, I own a Samick Sage. The manufacturer suggests a brace height of 7.5 - 8.5 inches. How did they determine those numbers?

[Roy from Pa]

My guess would be from years of building bows and testing.

[BMorv]

On my longbows I start at 6" and adjust from there.  It normally ends up pretty close to that.
 
If I were to start selling one of my longbows I would determine where the sweet spot was for that particular bow and design at 28" draw, lets say 6.25", and state 6.25" BH plus/minus .5".  I would imagine the bow companies do the same thing, but have lots of samples to determine that their range is correct.

[Mjl834]

BMorv, what length are your longbows?

There must me industry standards / charts out there that have this information.

Thanks for the replies everyone.

[Wolftrail]

I have a 68" FG longbow and it seems ok at 7 1/2".. I prefer a lower brace on my wood bows to reduce set and stress, about 5 1/2 - 6" from the belly side of the handle. A good fistmele as the old timers say. Recurves slightly more because of the Deflex.

[BMorv]

My bows average 66" and they are all wood.  
Fiberglass bows can get by with higher brace heights as the fiberglass doesn't have memory.  The big box manufactures of FG recurves and longbows probably have standards but I doubt many on the bowyer's bench have that information as they set the brace height that works best in each bow they design.  
 
I could make a deeper cut in my riser and gain .5" brace height, but all I really care about is how it feels in my hand when I shoot it.

Sorry if this isn't the information you are after, but BH is about number 165 on the list of things I worry about when I make a bow.  I adjust it till if feels right then leave it there.  

Maybe pow wow would have more answers?

[mwosborn]

It seems as if you are asking for a "formula" to determine brace height.  I am not aware of a formula that anyone uses other than to get in the ball park.  11-13% of bow length.  Then it is experimenting as Eric described for each bow.

The bottom line and reason for brace height is so that you don't hit your hand or arm with the string...  I have found that anything under 6 1/5" I start hitting my arm... Then after that is performance and noise... Pick one and start tuning your bow to gain or avoid one of these... I think the two may run hand in hand... If you have way too much brace height you will lose performance and possibly over stress your bow...  So in a nutshell that is how you determine brace height...  Not too much science to it...

[Mjl834]

Thanks for the input.  Yes I am looking for a formula that will get me in the ballpark then I can fine tune from there.

Thanks again for all the help.

[Roy from Pa]

You are way over thinking this. String it up with a 7 inch brace height and go from there. Follow what Eric wrote.

[kennym]

"I have found that anything under 6 1/5" I start hitting my arm..."

Rich, you measure in fifths? Thought only Roy used shots to measure?    

Good advice above , its only a guideline that folks put out.

[Roy from Pa]

OK OK Buckswheat's boy....

I'm gonna start the 2018 thumpin list tonight.

Guess who is gonna be at the top Of the list?

           

[kennym]

Its not lonely at the top.... of this list!!  

LOL...  Well...  That's what you get when you buy a tape measure at a Harbor Freight Clearance Sale...

[Roy from Pa]

I needs to get me one of them thar digitamal tape mearures, like ole Kenny has.. Then I could measure me up some lambs..    

[kennym]

I figured you had done checked out all yer lambs, Roy...