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Define "stack" or "stacking"

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dougedwards

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Discussion starter · #1 ·
I have a 29 1/2" draw length and am told that some bows are too short for me because short bows tend to "stack" when pulled beyond the normal 28" AMO draw. Does this simply mean that the draw weight jumps in an extravagant way or is there some other negative implication that applies to this term?

What if I started out with a lighter draw weight and because of the "stacking" characteristic of increasing the weight in disproportional measures past 28" discovered that the weight is perfect for me?

Is that possible or is there any other negative implications associated with this term?

Doug
 
#2 ·
Doug, it's all relative to "what point" you are at in the working radius of the limbs. Lot's of variables go in that.

The negative implications that I can see is getting back decreasing performance for increasing work, with both happening at an increasing rate. IOW, there comes a point in the string angle where even through you are pulling more poundage, you are not building any more real spring tension to release into the arrow. IOW, I can pull on a closed door handle all I want, but the spring back will be nill.
 
#3 ·
Yes, simply means that the weight will increase as you draw past 28"...some limbs stack more than others. It could be 1# per inch, could be 2. I've got a set that are rated at 26#@28" but at my DL they are 35#. Another set that are rated at 36# that are 41# at my DL (30ish)
 
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#5 ·
If you rely on stacking to get to your target draw weight, you might run into the predicament where your shots start getting erratic.
The bow is fine(although exceeding 100% load probably isn't good for the life of the bow), but at that extreme load, any form flaw that affects draw length no matter how small will be greatly magnified.
 
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Discussion starter · #6 ·
Dave V said:
If you rely on stacking to get to your target draw weight, you might run into the predicament where your shots start getting erratic.
The bow is fine(although exceeding 100% load probably isn't good for the life of the bow), but at that extreme load, any form flaw that affects draw length no matter how small will be greatly magnified.
Click to expand...
Even at draw weights of 42-48# at 28"?
 
#7 ·
#8 ·
Doug -

Stacking means that as your draw length increase the weight begins to go up exponentially, rather than linearly.

All limbs will show stacking at some point, based on material and geometry.
(There are a number of "technical" reason for a bow stacking, but I'll spare you those for now.

The trick is to find a rig/configuration that stacks AFTER you have reached your full draw.

With any ILF rig, the stack point can be modified by simply adjusting the amount of reflex/deflex with the limb bolts.
With non-ILF rigs, the only option would be to lower the brace height, but that yields limited results.

Viper1 out.
 
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#9 ·
To only add a small bit,

When you're in the 'stacking' region, you're getting a whole lot more holding weight with a little more draw, but you're not really getting a whole lot more stored energy, because for most of the power stroke, you were pulling the bow as if it were much lighter.

Technically speaking, it's about how the holding weight at your draw length relates to the area under the draw force curve. Example...

If you have a bow that 'stacks' a lot, after say 28", and you're holding 30, let's say it's a 40# bow, but it's stacking yard, so at 30" it's 46#.

Take a bow with a smoother draw force curve to 30" (less stacking), and it may have the same holding weight at 30", 46#, but at 28", it might be 44#, in the more extreme scenario. The smoother bow may also have more draw weight at 26 and 27 inches as well.

The bow that 'stacks' more at your draw length will also have more variation in arrow speed (and and possibly spine requirements), as a function of draw length. I.e., you creep a little, or fail to expand as much, and the arrow flight differences are greater...

That being said, so long as you're not stressing the materials by bending them beyond their safe operating range, and it shoots fine for you, it's not a problem :)

So, speaking roughly, you'd be comparatively getting a lot less zing for your holding weight.
 
Discussion starter · #10 ·
That is what I was looking for but did not really know how to ask the question. There comes a point where weight increases and efficiency does not. I would not think that could occur over just a 1 1/2" span but I must be wrong.

Doug
 
#11 ·
dougedwards said:
That is what I was looking for but did not really know how to ask the question. There comes a point where weight increases and efficiency does not. I would not think that could occur over just a 1 1/2" span but I must be wrong.

Doug
Click to expand...
Well, it's not an instant thing, it's gradual. The degree of which you'll see a difference depends on the rate of the change. On my Predator recurves, the published draw force curve indicates the beginning of 'stacking' on their 'classic' setup somewhere between 28 and 29". With their Velocity riser, which adds pre-load to the limbs, as well as reducing the brace height for a longer power stroke, essentially simulating a longer draw length, my 28 3/4" draw pulls on the libs more like a 30" draw, where if you looked at the curve, you should be well past the stack point, but it's a pretty gentle 'stack', so I don't really notice it.

Also, what you're used to has a lot to do with what you feel. If I get used to pulling Border limbs, or other similar super recurve design, most standard recurve bows are going to feel like they stack a lot, comparatively.

Regardless, if it was optimal at 28", (whatever that means, because there is a degree of personal preference when it comes to feel, some people like a little stacking as an indicator that they're at full draw, kind of like a 'stop'), then another 1 1/2" isn't going to make it suddenly suck, unless the design is pretty harsh. It just means that it's going to be different, and if it was optimal at 28", by whatever metric you choose, at 29 1/2", it isn't.

So long as the limbs can take it, it isn't actually a less efficient setup, in the technical sense of the word. You don't get proportionally as much energy out of the bow, at the holding weight, because you aren't putting in as much energy into the bow for that holding weight, if that makes any sense.
 
#12 ·
Viper1 said:
Doug -

Stacking means that as your draw length increase the weight begins to go up exponentially, rather than linearly.

All limbs will show stacking at some point, based on material and geometry.
(There are a number of "technical" reason for a bow stacking, but I'll spare you those for now.

The trick is to find a rig/configuration that stacks AFTER you have reached your full draw.

With any ILF rig, the stack point can be modified by simply adjusting the amount of reflex/deflex with the limb bolts.
With non-ILF rigs, the only option would be to lower the brace height, but that yields limited results.

Viper1 out.
Click to expand...
This is a good explanation
 
Discussion starter · #13 ·
Soooo.....after reading these responses I have surmised that it would not be best for me to purchase a 58" longbow 44@28 (48# is just about perfect for me at 29 1/2") because I may well not get proportional benefit out of the last 1.5" of draw not to mention having to deal with a more acute string angle.

In the words of the late RosaneRosannadanna......... "It's always something"
 
#14 ·
I'd say that would be a bit short....I would think that mid 60" would probably be a better bet.
 
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#17 ·
dougedwards said:
Soooo.....after reading these responses I have surmised that it would not be best for me to purchase a 58" longbow 44@28 (48# is just about perfect for me at 29 1/2") because I may well not get proportional benefit out of the last 1.5" of draw not to mention having to deal with a more acute string angle.

In the words of the late RosaneRosannadanna......... "It's always something"
Click to expand...
I think it may depend on the longbow. If the bow in question is of the hybrid style they are very popular in lengths shorter than what would normally be considered a "longbow". The limb design allows them to work at a shorter length. Some of the most popular hybrids are even shorter than 58", take a look at the LaClair "Shrew" and Big Jim's "Thunderchild". Short bows can work just fine for someone of your draw length if they are designed that way. An extra 1.5 inches of draw beyond 28" is well within the acceptable working range of many bows.

If this is a used bow it might be worth trying out, you can always resell. You won't know if you like a short bow until you try one.
 
#18 ·
i think big jim has a 30 or 31 inch draw and shoots the TC fine. i've seen my old TC on the scale and the weight stayed the same out to 31 and some change.
i have a 29.3 draw and i've settled on that sarrells you traded me doug. the bow shape and limb shape have a lot to do with it. i think i'll stick with 60" plus bows from here out tho and only r/d long bow designs.
 
#19 ·
It depends on the bow design. I have a draw length around 30" and I like to shoot 66-68" longbows. I have noticed that longbows generally will gain 2-2.5#s an inch at the end of my draw length, this gives the bow a sense of a heavier holding weight. Therefore, the longer bow will generally minimize this.

On the other hand, I have an Omega Delta Recurve which is just under 59" tip to tip when strung and around 40#@30", and this is one of the smoothest bows I have ever shot. So the design of the bow can also play a factor, where string angles can be minimized with proper design.
 
#20 ·
in my opinion, Stack is anything less smooth than your used to.
You read posts all the time. Such a bow is super smooth. and yet others feel it stacks.
Its all relative.
there are bows out there that defy the 2lbs per inch rule by about 1/2lbs and these feel super smooth
there are bows that defy that even further by only pulling 1lbs per inch or less up to some heavy weights. like 55lbs. from short models. an example would be a 40lbs 60" bow wuling 0.6lbs from 29-28"

these later bows make the older models feel like they stack, while they make conventional smooth bows feel like they stack. and they make the 2.5lbs per inch feel stacky.

so it depends on what you shoot, as to what you discribe as stacky.
its relative.

out of these four examples. which one is going to feel smoother
1: 40lbs at 28" 60" bow 28-29" 2.2lbs gained
2: 40lbs at 28" 70" bow 28-29" 2.2lbs gained
3: 40lbs at 28" 60" bow 28-29" 1.7lbs gained
4: 40lbs at 28" 60" bow 28-29" 0.6lbs gained

All these are real trad bows. that can be bought.
 
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