Brace height and its affects on speed

[widow sax]

I got a new to me acs longbow. I deceided to check what affects changes in brace height has on speed. First let me say I have posted that I believe it does not have a affect on speed so I thought I would back up my words with results. I have a very consistent form, draw and release I usually only very one fps high or low so the results schould be accurate. I have worked with this bow some and I am using a brace height of 7" so I will start lower then this and move up 10 twist at a time untill I go over one inch past starting point and then go back to my 7" were I will keep this bow. I used three different arrow weights let me know what you think and any thoughts about the results. This is a 12" riser 58" bow 45@28" bow I draw 26.5 usualy but with this lower lbs may be 27".  

6 13/16 brace height

387gr 182fps 452gr 177fps 517gr 166fps

7 1/16 brace height

387gr 182fps 452gr 175fps 517gr 165fps

7 5/16 brace height

387gr 182fps 452gr 174fps 517gr 165fps

7 5/8 brace height

387gr 182fps 452gr 174fps 517gr 165fps

7 15/16 brace height

387gr 180fps 452gr 174fps 517gr 163fps

I then went back to my 7" brace height.

387gr 185fps 452gr 178fps 517gr 167fps

I then deceided while I have the crony setup I would check the difference with a hold at full draw and release and the way I shoot a pull threw release. I used one arrow for this it was the 452gr arrow.

Hold and release 174fps

Pull threw release 178fps

So what do you think about the results!

I think I found the correct height for this bow and I will keep it a 7"!

As I thought untill you get a good bit over it does not have any real affect on speed. Widow

[Benny Nganabbarru]

Thanks for posting your testing! Interesting stuff, and food for thought... To be honest, I have never been much of a tinkerer with brace height, and approximately the recommended one is always good enough for me, being unable to tell the difference (not counting some of my learning episodes of either way too low or way too high).

[john gerrard]

Thank you for posting,very interesting. I am another one who only tinkers a little with brace height. I work mostly for quietness. Brokenwing

[Joe Subler]

Widow,  did you take much note about any sound difference at the various brace heights?

Joe

[Flingblade]

Nice to know.  I recently padded the ends of my string with wool yarn to quiet my Black Widow PSA and it changed the brace height from 8 1/2" to 9" which is the top of the bowyers recommended brace height.  I liked the way it shot at 9 better so I left it but soon found that the arrows I was shooting were overspined as most shots were well to the left.  I switched from Arrow Dynamics traditionals to the trad lites and they fly great.  Did you notice any difference in how the arrows flew at different brace heights?

[Maxx Black]

Thank You for taking the time to check this and then record for us . I find it interesting as I'm always tinkering as well but without really knowing the speed changes.(mostly trying to quiet the bow). That amount of speed changes(lack there of) makes me feel better when I'm playing around. Maxx

[Rob DiStefano]

i think that, with trad typical hunting distances in mind (10-20 yards or so), the difference between 163fps and 178fps is nearly meaningless.  i take that back - it is meaningless.

what's most important to me is not dialing in the fastest arrow speed for a particular bow, it's finding the best "stability" for a bow and its arrow.  there is a brace height *range* (not just one specific brace height) that will allow for the bow's best stability with me pulling its string.

[Swamp Yankee]

Interesting, but for a max difference of 5fps, I'd be looking for quiet over speed.

[**DONOTDELETE**]

That tells me you have a pretty nice set of limbs on your bow with good preload. That... and long bows are a bit more forgiving to different brace heights until you get real low. but testing down to 5" isn't practical or she'd be biting your wrist.

Different bows with different limb designs are going to test differently too. Some recurve limbs are a lot more sensitive to brace height. You may not see a huge jump in speed, but noise and vibration is where you'll notice most the difference.


each bow design has a sweet spot where the tension of the string stops the tips clean with the least vibration.

[Rob DiStefano]

Originally posted by Kirkll:
That tells me you have a pretty nice set of limbs on your bow with good preload. That... and long bows are a bit more forgiving to different brace heights until you get real low. but testing down to 5" isn't practical or she'd be biting your wrist.

Different bows with different limb designs are going to test differently too. Some recurve limbs are a lot more sensitive to brace height. You may not see a huge jump in speed, but noise and vibration is where you'll notice most the difference.


each bow design has a sweet spot where the tension of the string stops the tips clean with the least vibration.

well said, sir - and right on the money.

[jhg]

Originally posted by Rob DiStefano:
...it's finding the best "stability" for a bow and its arrow.  there is a brace height *range* (not just one specific brace height) that will allow for the bow's best stability with me pulling its string.

I agree with Rob on this one, but its always worth the effort to explore and experiment. There is nothing wrong with finding within that stability and quiet the sweetest performance your tackle can deliver, whether an extra FPS or 20. Numbers do tell us something. Its worth knowing what they are, even if in the larger context of trad hunting where skill, both woods wise and at the shot, are paramount. But we all know that already anyway ;0)

Joshua

[widow sax]

Yes I was checking how the bow felt and sounded with the lower brace height when I untristed the string the beaver balls also untwisted and made a vibrating or buzzing sound and the string seamed to feel that way also. I have found if you do not get beaver balls tight they make a buzzing sound as the string vibrates against the leather inside. AS I twinsted up the string the balls got tingter aroung and that noise went away. I was shooting close so I could not tell any small change in arrow flight but there was a change from the lowest to the hightest in the way they stuck into the target. There was a difference in the sound from the arrow weight but you would expect the lighter one made the most noise and the heaver one made the least. I did not use a crony to come up with the seven inch brace I just shot it after and found I liked 7" the best I got lucky that it was also the fastest for some reasion. The only thing I need to do in make up my mind what weight arrow I will shoot I would like to shoot around 170fps to 172fps as I am use to that trajectory. I know a few fps won't make that big of a difference in that I am going to try to get close to 500grs that schould work for me with this bow I also did a little math and found that this bows speed changes 1.3fps to 1.34fps for every 5gr of arrow weight. I may try this with one of my widows somedsy but I did not want to mess with them now because I am hunting with them. Thanks for you imput guys.   Widow

[widow sax]

Sorry about all the missspelled words I was typing fast and did not proofread it enough I guess O and buy the way I can't spell worth a lick anyways LOL.   Widow

[widow sax]

(i think that, with trad typical hunting distances in mind (10-20 yards or so), the difference between 163fps and 178fps is nearly meaningless. i take that back - it is meaningless.)

I personaly believe that if I'm putting the effort of pulling the bow then I schould get the most out of the bow for that effort but not at the expence of making the bow shoot bad. It still has to be stable and all the other things that make it a good shooter. I think my findings kind of point out that there is a range and in that range the speed does not change that much so you can find were your bow works good and you do not have to worry about its affect on speed because it realy does not affect it. That is what I was trying to prove because I always heard people saying that lower is faster and higher is slower I always set the bow up to were I liked it and never worried about it but believed it did not have a big affect on the speed. I do not think any infomation is bad you take from it what you want and use it however you want. I happen to love the tec side of things and always will I like to tinker and see its affect be it in speed, arrow flight or how the bow reacts thats what I injoy doing and sometimes post it for all to see. The word speed in now a bad word in the trad comunity it is just one of the many componets that make a good shooting and performing bow there is lots of others and I'm not saying it is the most important one either it is just another measurement.    Widow

[Javi]

Now repeat the test going down to 6" and see if you get the same results..

Note: I've done almost the same tests with very different results.. a 49lb@28 1/2" mild R/D longbow shooting a 658 grain arrow.. difference between 7 7/8" and 7 1/4" was 14fps.. above 7 7/8" showed no effect... under 7 1/4" speed fell off slightly.

It's fun to play with stuff....  

[widow sax]

That is amazing good for you. I could not go to much lower because I had a short 6 strand skinny string on the bow that I had on hand. I'm not shure I would want to go lower anyways I would hit my arm I have womans elbow it bends inward and I would not like the way the bow felt either even if it did go faster.I could put the string that came with it on and go lower I may do that when I get time after all it is hunting seasion LOL not that I'm seeing much to hunt. I am still playing around with the two strings but with the string that came with it i liked 7" also.    Widow

[Sixby]

I agree with both Rob and Kirk on this one. However in my opinion 5 fps is vry significant in that it basicaly represents 5 lb of draw weight to lose that much speed.

It becomes even more important when we are talking about building efficeint short draw bows for those that are already being challenged performance wise or for those that want the most performance out of an extremely heavy arrow for large or dangerous game.

However a good quiet bow of basicaly any shootable speed is suitable for close range shooting at deer size animals.

That said I will always pick a fast , quiet bow over a slow quiet bow. I also will not own a bow I have to put over one set of silencers on to make it quiet with a hunting weight arrow. 9 gpi or better./

God bless you all, Steve

God bless you all, Steve

[Rob DiStefano]

i hear you, steve, about the fps/holding weight thing.  however, i will always take "stability" over *added* fps/holding weight, because "stability" allows consistency.  i think most of us know how fast bows aren't necessarily the most consistent/accurate bows.  to get the most outta yer gear, one DOES need to put in the efforts ...

[**DONOTDELETE**]

Originally posted by Rob DiStefano:
[qb]      i think most of us know how fast bows aren'y necessarily the most consistent/accurate bows.    

I'm real curious why you would make that statement Rob?  

I understand that generally most of the "Fast" bows you see out there the guys are using ultra light arrows...and light weight arrows are real sensitive to a poor release vs heavier shafts.

but is this the reflection of the archer, not the bow. To say most fast bows are unstable, would be like saying most fast cars are unstable. There are bows out there that cast heavy shafts at impressive speeds that are rock solid in the stability dept.

What difference does this extra speed and extra power in the bow mean to a hunter that shoots 10-20 yards?

Flat trajectory for threading the needle, or missing that branch....

 and.... getting that extra power at a lighter draw weight is icing on the cake for when that less than perfect shot hits a shoulder....

Seems to me.... a guy might like those qualities in a bow.

[Rob DiStefano]

Originally posted by Kirkll:
 

Originally posted by Rob DiStefano:
[qb]      i think most of us know how fast bows aren't necessarily the most consistent/accurate bows.    

I'm real curious why you would make that statement Rob?  ... [/b]

didn't say all bows, but *some* bows can be incredibly fast - maybe even by 15/20fps - but at those speeds they may have no stability/consistency, which affects accuracy.  

having such a bow, what would you opt for, speed or stability - or sell it and get a bigfoot?  :D