The stiffness of a pole increases exponentially

[Bruce Caldwell]

Stiffness of a Pole
As a manufacturer let me offer some facts here and get rid of a few misnomers that other pole makers do but not ESSX!
PS thank you Rainbow girl and well said!

As long as you know you are jumping on a safe pole (ie. one that is above your weight), it is better to go by the flex number. For both psychological reasons and precision reasons, the flex will always tell you more about the pole than the weight.

This is true vault3rb0y thank you however please do not get hung up on the difference between a 16.0 and a 15.5 the actual comparison on ESSX is about 2 lbs.
Try to not put so much value on a flex number! especially ordering by a flex number it is so difficult to explain that a 17.4 and 17.6 are the same size in the weight rating!
The flex number of a 12' 2" PVC plastic tube is the same as 12'-125 lbs test pole but you would not vault with it?

BUT make sure you understand two things when comparing poles using flex:

1.) Longer poles will always have a higher flex number, if they are flexed to the same "weight". Essentially a 16' 160 is stiffer than a 15'6 160 if you hold at the same point. It seems obvious, but if you go by flex numbers the 16' may flex to 22.0cm and the 15'6 may flex to 18.0cm, and if you dont look at weights you could jump on a pole without realizing how big it is.

I suggest you always look at the weight first before jumping then the flex. The flex number means nothing to you unless you note the length, the weight then the flex. Flex just shows a relative stiffness within that weight rating, telling you how much stiffer or softer that pole is to any other poles that length!

vault3rb0y
2.) The stiffness of a pole increases exponentially. If you compare the relative stiffness of 20cm, 19cm, 18cm, 17cm, 16cm, 15cm flexed poles.... the stiffness between the 16cm-15cm poles will FEEL much greater than that of the 20cm-19cm. The physics behind that one isn't terribly complicated, but also isnt worth getting into if this is just a summary.

vault3rb0y You offer a point I feel is worth diving into thank you for mentioning it!
Other companies may not recognize this info you just presented!
Other's flex their pole with more glass within the span claiming to get a better and more accurate flex? However , my opinion is this is not a true statement as a flex measure of more of the grip of the pole does not give you a more accurate flex especially when that area rarely bends or contributes to the stiffness of the pole's flex!
If one knows that on the ends of the flex scale you get a number that is stiffer or softer between it's flex numbers such as you have sited, then they could build the sail and structure of the pole to provide you with a pole that is not affected by this anomaly!
ESSX poles are built for performance, we make the patterns to get a safe, performing pole. IT is not just a stick of fiberglass rolled on a manderal! Engineering has been performed and tested over the years to provide the vaulter and coach with a fine tuned implement!
We build the pattern to get the weight rating and flex number correlation and we build into the pole the necessary things to give you a smooth jump pole size to pole size and length. No other pole company does that!
Let em give you an example; some other companies uses the sail piece with the small side to lengthen or shorten to provide a stiffer or softer pole! they may cut this pattern from 36" to 56" wider providing a stiffer pole and using 2-3 width of the sail from their standard widths of glass!
We feel this will provide a pole that requires one to adjust their timing as they progress through their pole range to a stiffer pole. this waste season time!
A better method is expensive and much more custom to building a pole such as ESSX does! The sail piece small side stays the same length for each diameter manderal ( which is the mold used to wrap the pole on) and the width of the sail determines the increase or decrease of stiffness to the pole. Thus a pole that is smooth bending the same each time except just a little stiffer like you expect!
It is very difficult for other manufactures with the volume they are running to stop production lines and provide you with such a custom part!
And they buy their glass is slit to a certain width and to cut this down for you to accommodate a better pole would increase their costs and is only done on World Class poles custom made!
(See drawing and photos I am referring to "A" and "B" changed to get a stiffer pole rather than what we do which is smoother only moving the width of "C" to get a stiffer pole!) http://officialessx.com/forum/index.php?s=f448616a05b3d6f2a1cb470482000dc4&showtopic=16&pid=17&st=0&#entry17
We call it the Xlogic System and it is why we are the only poles providing a smart label on every pole. The smart label tells the vaulters and coaches the flex number this ESSX pole compares to in other brand spans! Allowing you to compare to other brands in your bag!
It also provide the model number of the pole you may need to move to in your progression or one to move down too on bad weather days!
You want a custom made pole just like the World Class Vaulter get? Choose ESSX
1-877-367-3779
Call Bruce Caldwell owner to be custom fitted fro an ESSX custom Pole
cell phone 817-819-1472
visit the JOE ESSX and the ELLA ESSX BLOGS at
http://www.myspace.com/joeessxflames
http://www.myspace.com/ellaessxflames

[kcvault]

I suggest you always look at the weight first before jumping then the flex. The flex number means nothing to you unless you note the length, the weight then the flex. Flex just shows a relative stiffness within that weight rating, telling you how much stiffer or softer that pole is to any other poles that length!

Not everyone has the advantage of jumping on poles that are all from the same company. Also I know the flex numbers from gill, and spirit tend to be the same but the weight ratings tend to be different. (I know nothing about essx flex numbers.) For example I have I have a 15'6 17.6flex 180lb spirit pole, The next pole in my serious is a 15'6 17.2 175lb carbon fx pole. If I knew nothing of flex numbers and came across these poles in a meet I would move up to the 180lb thinking it was the bigger pole. Also I have three poles in my serious that are all 16ft carbon pacer 190lb poles. One is a 17.0 that I can jump 16ft on, one is a 16.4 that I could jump 16-6 on and one is a 16.0 that I can jump 17 ft on. If I went off weight ratings I would be in a lot of trouble I possible went from my 17.0 to my 15.6 195 about a 7 1/2 pound difference. Not every company has a 2.2lb increment to go off of so by not going off the flex numbers vaulting could become much more dangerous then it needs to be. Also no matter what company every pole that I have put on a flex machine the number I get is within 3 tenths of the number they give though the weights may not necessarily match up. (I have not yet flexed essx poles) Therefor the flexes tend to be a much better indicator then the weight as long as the poles are the same length. Also if you have access to a flex machine and the ability to flex 16 ft pole as 15-6 poles or visa versa you can always go off the flex number relative to where you are holding. I know you will disagree with this but understanding this has allowed me to jump 2 1/2 ft over my top hand on a pole that was below my body weight. This is because where I was holding was about 25lb stiffer then the rating on the pole. An understanding of this could save a lot of programs from having to close do to lack of money for equipment. For example if an athlete has a 13 ft 135 a 13-6 130 and a 13-6 135. Really they have a 13ft 135, a 13ft 140, and a 13ft 145. As long as they do not raise there grip remembering to treat all poles as 13ft poles and not grip above 12-9. You may disagree but I have seen this work time and time again. Also knowing a 13ft poles flex as a 12-6 pole and as a 13-6 pole could save a lot of money. Bad for the pole manufacturer but good for the sport of pole vaulting. (Again this has not been tested on essx poles so I do not know if the same thing applies). This is my last story of why to go off flex numbers instead of weight ratings. Last year my wife was jumping on a 13ft 150 carbon mystic pole she blew through the pole and over bent it a little bit. I said with out thinking go to the 13ft 155 spirit the pole broke split her hand open and ended her season. When I checked the flex I found out the 155 was a full cm softer then the 150 I moved her down a pole when she was over bending the pole without even knowing because I went off the weight label.

---Kasey

[KirkB]

... knowing a 13ft poles flex as a 12-6 pole and as a 13-6 pole could save a lot of money. ...

I didn't use this trick to save money. I used it to know ... with CONFIDENCE ... that when I went up a pole and kept my grip the same (no matter what the pole lengths), I'd be able to do everything EXACTLY the same and expect just a little bit more stiffness. To do this, I calibrated my own poles with a 50 pound weight in the middle ... per Herb Jenks.

Without this detailed knowledge, I might have been hesitant in my technique ... and "he who hesitates is lost".

KC, you make some good points, but remember that we're much more experienced than HS vaulters and HS coaches. For them, the pole manufacturers need a more simplified system of calibrating weights and flexes.

I like ESSX's system of using kilograms instead of pounds. This is a simple math principle, related to "significant digits". Basically, becuz there's 2.2 kilograms per pound, ESSX uses kg and calibrates [arguably] ~twice as accurately as the other manufacturers. For the other manufacturers to follow suit (sticking with imperial weights), they would have to calibrate to the nearest 2.5 pounds.

But if the other mfrs wanted to be even MORE accurate than ESSX, they could go to the exact pound or two. Let's say they went with only even-numbered pounds. This would give them 5 poles in every 10-pound range (they presently have 2, and ESSX has roughly four-and-a-half).

HOWEVER, this would mean that they'd have two-and-a-half times the Model Numbers, designs, and inventory (to hold sufficient supply for the demand of each weight). This would increase their costs. Altho the cost of the pole is an important factor in selecting which one to buy, it's not as easy as you might think to jump up 5 pounds in weight (for a given length). So for these reasons, I applaud ESSX on their system ... even tho I have no personal experience with their poles.

The logical conclusion to this ... which is what Bruce Caldwell is trying to say ... is that ESSX poles might cost a little more, but THEY'RE WORTH A LITTLE MORE.

Caveat empor!

Kirk

[kcvault]

To do this, I calibrated my own poles with a 50 pound weight in the middle ... per Herb Jenks.

I use Jan's flex machine which appears to be the same system as yours. The flexes match that of the number gill or spirit puts on there poles.

The logical conclusion to this ... which is what Bruce Caldwell is trying to say ... is that ESSX poles might cost a little more, but THEY'RE WORTH A LITTLE MORE

I have used Essx poles for the first time this year and really like them, i think they may be my favorite pole I have jumped on but can't decide between them and the old carbon pacers (I will say though that it is a poor mechanic that blames there tools.) I think 2.2lb or 1kg increments is a great idea. With 2.2lb increments essx has taken a lot of the guess work out of pole vaulting. In a world with no cost and unlimited supplies i would say it would be ideal to only go up one pound at a time.

I am simple saying understanding relative weight and stiffness is a huge advantage not just because of the cost but also safety, and confidence. you may have the next pole in your serious and not even realize it. Also people need to understand that if they have a 14ft 180 a 14'6 180 is not the next pole (I thought it was in high school which resulted in a lot of pain). A 14'6 175 is the next pole. i am not using science or knowledge of how a pole is made to come up with my conclusions I am using my own experience and what I have observed. I know that I can jump nearly the same height on a 15ft pole with a 15.2 flex as I can holding the same height on a 15'6 pole with a 15.2 flex when flexed as a 15 ft pole. The pole may roll over slightly differently but the end result is basically the same. (I could show video to back this up) Also six years of helping with Jan Johnson camps I have learned that when using relative stiffness you can almost always find a camp kid the next pole to move to. Of course Jan has a lot of poles but with out an understanding of relative weight and stiffness he would need 2 or 3 times as many poles for the camp to run smoothly.

---Kasey

[Bruce Caldwell]

For example I have I have a 15'6 17.6flex 180lb spirit pole, The next pole in my serious is a 15'6 17.2 175lb carbon fx pole. If I knew nothing of flex numbers and came across these poles in a meet I would move up to the 180lb thinking it was the bigger pole.

I think this is why it is so confusing. Is the FX stiffer or is it the carbon return that is faster?
I would tell a coach or vaulter to follow the lbs on the two poles! So reveal to me which one was actually stiffer?
Bruce

[rainbowgirl28]

I would tell a coach or vaulter to follow the lbs on the two poles! So reveal to me which one was actually stiffer?
Bruce

I would too seeing as Gill flexes their 15'6 poles on a 15'6 span but Spirit flexes theirs on a 15' or 16' span, I forget which.

[kcvault]

I think this is why it is so confusing. Is the FX stiffer or is it the carbon return that is faster?

My first thought was that carbon poles return faster. But I land deeper in the pit on the spirit so I know the spirit must be softer. Either way when going with the same brand of pole and you have two or three poles of the same weight you should definitely go by the flex number. Also I remember the first time I jumped 16 ft I went from the 17.2 carbon fx to a 17.0 pacer fx. On the 17.0 I made the bar and landed in the pit slightly shallower. Before this I always thought pacer fx fiberglass was softer then spirit or the carbons. Now I believe the best predictor of push off and where you are going to land in the pit is flex number regardless of pole brand.

It may be true that one pole is lighter then the other or one is more likely to break then the other but in my experience flex number determines the softness or stiffness of a pole as long as we are talking about poles that are made of fiberglass or carbon fiber. I am not saying this as fact but in all of my experience with flex numbers this has been the case. If I come across a pole that what I am saying does not seem to hold true I will be sure to post it. I have not flexed my essx poles so I do not know if this holds true for them. I have to go off the factory flex. I have a 15ft 180 16.4 spirit and a 15ft 180 15.2 essx I jump way higher on the 15.2. Also when I am able to jump again in a couple weeks I have a 16ft 18.1 spirit and a 16ft 18.1 essx I will be able to tell you then if they react basically the same, and if what I am saying appears to hold true for essx as well.

I would too seeing as Gill flexes their 15'6 poles on a 15'6 span but Spirit flexes theirs on a 15' or 16' span

This is why it is huge advantage to find some where you can flex your poles. The flex spirit gave on my 15'6 pole was 20.0 which is what I got when I flexed it as a 16 ft pole. I got 17.6 when I flexed it as a 15'6 pole. It would make things a lot easier if all the pole companies would just flex there poles the same though.

---Kasey

[Bruce Caldwell]

My first thought was that carbon poles return faster. But I land deeper in the pit on the spirit so I know the spirit must be softer. Either way when going with the same brand of pole and you have two or three poles of the same weight you should definitely go by the flex number.

Let me share some info I have learned over the years!
Carbon when laid up in a pole with all the fibers going up the pole will provide you the strongest and stiffest use of the material.
Thus using less glass you have a very light weight implement. However you also have a pole difficult to bend initially and one that will straighten up sometimes too abruptly!
A way to confirm this is to have someone stand to the side of your jumps and watch for two things!
1. Do you lose some take-off energy at the plant does your arms collapse far too much to transfer the energy consistently?
2. At the top of the vault are you actually upside down or more like a flag pole in comparison to the Spirit pole?
You are correct in saying

but in my experience flex number determines the softness or stiffness of a pole as long as we are talking about poles that are made of fiberglass or carbon fiber.

Flex number does determines the softness and the stiffness of a pole within the brand, the new variable is how the carbon is laid up in the pole. People will not be able to use that myth, unless they take into consideration how the pole is made!
a. some carbons are straight carbon fibers to the ENDS OF THE POLE
b. some carbons are straight carbon fibers to the ENDS OF THE POLE and a spiral wrap to dampen the stiffness
c. and others are cloth with carbon strengthening both directions depending on the resin content a carbon pole with layers against each other without a layer of Fiberglas is subject to inner de-laminar failure IDF well known term in the industry to sell more parts such a gold shafts and hockey sticks. I call it built in obsolescence http://www.merriam-webster.com/dictionary/obsolescence to sale more poles.
I watch a man who worked for thermo-flex the red poles and he once broke 10poles at a show on a flex machine and kept laughing "that if they lasted forever we would not sell many! And if the break we sell another pole!" The next year no one wanted to jump on the red pole that got the nick name as the pole that talks to you with a crackle!
The whole thought runs chills up my back. I have and will be making poles that last longer, I want to sell them because they work and never let you down!

[kcvault]

I was wondering how exactly is the weight of the pole determined?
Is it determined before hand based on how much material is used?
Or is determined after based on a machines calibration?

I understand how flex numbers are determined. Maybe understanding how weight ratings are determined will give me a better understanding of the dangers of going strictly from flex numbers.

---Kasey

[Bruce Caldwell]

Yes to make a really good pole one must calculate the structure's needs. Like I mentioned before a 2" schedule 40 Pvc white shipping tube has the same flex number of a 12'4"-125 but I would never jump with one they will not hold a vaulter. And a paper tube use to roll up a rug is also the same but will not bend and return!
The specific pattern cut is made up of blends of glass and carbon oriented to a function.
A fiberglass pole is made for a purpose no other tube is made for. FEA Finite Element Analysis allows one to build computer model of a pole and calculate the strands needed every 0.001mm one could if you had the time measure in nanometer. This finite structure can be built for function and performance without failure and best when you have the program model made by an engineer who understand the pole vault , and a World record holder and myself who has studied the pole vault for many years all calculating the needs for the vaulters.
As one gets closer to the larger World class poles of others you start seeing similarity to their performance as that of smaller length ESSX poles

The specific pattern cut is made up of blends of glass and carbon oriented to a function.
I had another pole maker who builds very good poles tell me my 15' poles had too small of a sail piece and wondered why I was shortening the sail. Yet he does not make carbon poles and was not familiar with the properties of carbon wrap that stiffened the pole instead and the need for such a tall sail was not necessary.
Was I making the sail shorter, yes but for the function of the pole, the stiffness within the areas needed were there, it just was not performed by the sail and the carbon covered the stiffness within that area as a substitute. One would upon looking at the pole would say the sail is lower no wonder the pole rolls over better, well yes that is the function but the stiffness is there as in non carbon poles just not used by the heavy sail material.
I have heard that only a few other pole makers have dived into FEA for confirmation and alteration of designs. others are using a pattern built they have used now for many years.
I would want a pole that is designed for function and not one that is designed to look like a pole!
Bruce

[Todd Haire]

Here is what I don't get.
We the consumer would have a better understanding of flex numbers if the manufacturers would inform us of how the flex number is determined. Specifically, the distance from each end of the pole that the supports are placed.
For example, I have a pacer 13'6" 170 16.4. Placing my supports 12" from each end, this creates a span of 11'6".
Placing a 50lb. wieght in the center of the span(5'9") and measuring the sag,give or flex, I came up with the same number,16.4.
The delimna is that I (and others I suspect) are unaware of the distances from top and bottom that are used to determine the flex numbers of all the different pole lengths. Not to mention that not all lenghts are even imperial numbers. I really like Altius poles, for thier value, but I cannot figure how to compare a 14'3" to a 14'er.Why?
Because we do not know the distance from each end of the pole that the supports are placed to determine the flex number.We know "it varies". That is not the answer.
Perhaps a way to explain what I am getting at is that a lot of things that we purchase have numbers.On my car I have a set of tires.225/75/15. These numbers tell me the the hieght, size and width of the tire.Understanding what these numbers mean helps me select the tires I want. If i don't know what they mean, I just ask the tire guy. Why cant the pole manufacturers do the same?
I agree with KC that some standard should be developed. If such a standard exists then perhaps one of the manufacturers would reveal it here on pvp.Surely the guys at the plant have some chart to tell them the afforementioned distances. Just post it here.
There has been a lot of discussion about flex numbers but (unless it's just me) I do not believe this particular aspect has been explained.

[rainbowgirl28]

Even if you knew the exact span, you would have a hard time precisely replicating the results because you don't have frictionless ball bearings and precise lasers to measure the deflection.

It doesn't matter what each manufacturer does. It's all relative. If you want to know how your 14'3 Altius compares to your 14' Pacer poles, you just need to flex them yourself on your own span, it doesn't matter if yours is the exact same as the manufacturer.

And that only gives you a rough idea anyway since the poles are designed differently and could respond differently depending on your takeoff. Ultimately you have to jump on them to see, comparing them on your own spans just gives you a rough enough idea that you won't go shooting off the pit or come up way short because the pole is a lot bigger or softer than you thought. Of course on any modern pole, the weight ratings give you a similar comparison.