A common Stiffness/flex standard?

[Divalent]

I just found out the expensive way that weight rating are useless as a measure of the relative stiffness of a pole if they are not the same brand. A new Altius 130 12'4 turns out to be about "1 pole" *LESS* stiff than a 130 11'8" (max grip) skypole (~ 10 years old), when compared at the same grip height. Whereas if the weight ratings was a similar benchmark for stiffness, then one would have expected the Altius to be a bit more than 2 poles stiffer: essentially, an 8 inch difference should be approximately 13 lbs.

IOW, I thought I bought a pole that, if gripped at the same 11'8" level as the 130 lbs skypole, would have behaved more like a 143, but got one that behaves like a 126. I do understand that because poles are rated in 5 lb increments, it would be reasonable to expect the difference to be as little as 8 lbs, or as much as ~18 lbs, more. But negative 4 lbs is 17 lbs (more than 3 poles!) less than my average expectation (and since it was less than the existing pole, that makes the new pole totally useless for it's intended purpose).

It seems to be a brand thing, because a 125 11'8" skypole behaves like a pole less than the 130 skypole, and a 130 12'9" Altius behaves as if its just a bit stiffer than the 130 skypole. IOW, it seems to be that the two brands differ in what stiffness/flexibility they consider safe for a given weight, using a different scale for making the call, and unless you are aware of the different scales the different manufacturers use, you rely upon the weight and length tables at your financial peril.

Did I just make a rookie mistake and fail to consult some source of information that is out there to make the right purchase? (If so, where can I find this information?) Is it well known that Altius poles are not as stiff as skypoles? (and how about other brands?) Or should I have called the manufacturer and explain what I had and what I wanted (because the manufacturers have this information)?

Is it too much to ask that the manufacturers to come up with a common standard for expressing the basic stiffness/flexibility characteristics of a pole so that consumers can at least get close? I mean, weight rating is supposed to be a measure of what weight of vaulter can use it safely, not necessarily what the stiffness is. And if they don't use the same flexing process, the flex number isn't helpful either. Otherwise, those charts of pole lengths and weight ratings useful only for comparing pole within the same brand. (because skypoles are about "15 lbs stiffer" than a seemingly equivalent Altius, and I presume other brands will also vary).

[Thanks for letting me vent :-]

[KirkB]

You can download the http://www.skyjumpers.com Relative Stiffness Chart from here: http://www.skyjumpers.com/articles/pvprogressiontable.html

The purpose of this chart is to provide a uniform way to compare poles of similar weight and length ... regardless of brand. This chart was constructed by Jan Johnson in a very meticulous way, with consideration of the various differences between brands. In fact, that was the very reason for him building the chart ... to provide a "standard" way to compare poles between brands. To compare poles of the same length within the same brand, you can use their flex #, but to compare poles from different brands, use this chart.

This assumes that you're gripping each pole of the same length at the same grip.

To my knowledge, this chart is reliable to roughly plus or minus 5 pounds of pole weight. And to my knowledge, it has been proven to be brand-agnostic ... altho I have no experience with the various brands. Someone else can speak to that.

It's important to understand that only poles of the same length can be compared to each other across brands ... and poles of different lengths will vary in "relative stiffness" according to the chart.

But if you map your poles to the ones shown on this chart, you should be very close (within 5 pounds).

Kirk

[rainbowgirl28]

So you mean it was a 12'130 Skypole?

In 2003, Gill redid their flex charts, and changed how they flex poles 12'6 and shorter to make them more consistent with each other, and the longer poles (and probably with other manufacturers as well). So an 11'6 130 Skypole from 10 years ago would most likely be more like a 12' 140 today.

I haven't used Altius poles much, so I am not as familiar with how they compare to other brands, but I think they are usually pretty comparable.

[rainbowgirl28]

I wouldn't say you made a rookie mistake, but if you're not personally familiar with how two brands compare at a given length, it's always good to ask someone who is.

[Divalent]

@Kirk, I basically am referring to that chart, which sorts poles by length (L/R) and weight (up/down), and applies a "6 inches = 10 lbs" offset. Using this same formula to compare the skypoles and the Altius, the main point I was making is that the actual stiffness of the Altius poles is 3 levels softer then I would have predicted relative to the skypoles. IOW, I thought I was buying a pole that was more than 2 poles stiffer (>2 rows down the chart, since both were 130, but the altius was 8 inches longer), but which behaves as if it was 1 pole less stiff. IOW, with two poles of each brand that I've been able to compare, these 10 yo skypoles appear to be ~3 pole levels stiffer than the altius (which is the same as saying that the altius appear to be ~3 poles more flexible than the skypoles)

I can't determine which brand is not behaving like the chart, because I can only compare the two brands to each other (and haven't looked at any other brands either). Rainbowgirl suggest that these older skypoles might be stiffer than one would expect.

@Rainbowgirl, It sounds like you have identified the discrepancy, which is that the older skypoles were originally considered less stiff than they are, or less safe for heavier vaulters than they actually were. This kind of illustrates the unsuitablity of using the weight rating as a *reliable* measure of stiffness when comparing across brands, since for a given stiffness the different mfgs have different ideas about what the max weight should be, and their "ideas" are subject to change in the future.

BTW, I was giving the length of the skypoles by the exact max grip (per the band on the pole), since it seems some manufacturers use the physical length of a pole as the designated length, even if that is not a full usable length (so I suspect these skypoles would be considered 125 and 130 lb 12ft poles, but with tape and all on the pole, I haven't found anything that says what they are.) The nice thing about Altius is that the Mfg stated pole length is exactly the grip length, so it is a lot easier to know you are comparing an apple to an apple within that brand. (and It would be nice if all the Mfg could follow that standard).

Anyway, it seems to me it would be nice if *everybody* could use the same benchmark to measure stiffness in a pole, and ideally something that even consumers can employ. If the deflection caused by a given weight that is hung at the exact mid-point of a span of the pole is a reliable measure of the overall general stiffness a vaulter experiences with a pole, it would seem a simple matter to come up with a common standard.

And if I were to suggest one, it would be something like: the weight would be in multiples of 1 gallon plastic milk jugs filled with water (2? 3? 4?), hung with no more than 6 oz (?) of hook/rope, placed at the exact centerpoint of the pole when spanning it's maximum length, the deflection to be measure in millimeters (or 1/16 of an inch). Additionally, if the max grip is not an even multiple of 6 inches, they also specify the flex at the next shorter span that is a multiple of 6 inches. If it IS the case that this simple flex measurement is a reliable measure of the general stiffness a vaulter experiences, then that information from the mfg should allow consumers and other mfg to appoximately know what an unseen pole is like, and consumers would be able to easily make their own objective measurement without a major investment in equipment. And with a common standard, consumers would more easily be able to determine that a given pole of a certian weight rating is on the soft end or stiff end of the "weight" range.

The downside of the current "standard" of using weight safety ratings are (to repeat), 1) different mfg have different ideas about what stiffness is safe for a given weight (so cross brand comparisons are unreliable), 2) those mfg ideas are subject to change, 3) those ideas are unknown to consumers, and 4) even from the same mfg, the weight rating is in 5 lb blocks, and so can mask up to a 4.5 lb difference in stiffness.

[rainbowgirl28]

Jan's chart is based on the length of the pole, not the max handgrip, so thinking in your head that they are 11'8 poles is part of what is throwing you off. Max handgrip only applies to US high school vaulters, everyone else can and does ignore this.

12'4 poles are a little tricky. I have found that the 12'4 ESSX compare more closely with the (modern) 12'6 gill poles in terms of weight rating, not sure about the 12'4 Altius, I think they might be closer to the Gill 12' length. Altius has made changes to their flex charts over the years as well, but I don't know exactly when and where. 12' Spirits tend to run a little stiffer than 12' Gill poles, but since Spirits go 10lb increments and Mystics go 5lbs, it gets a little tricky because you're dealing with a wider range of flexes on the Spirits.

I always recommend that coaches try to stick with the same brand at a given length, especially on the sub 13' poles.

Also, remember that flex number is not the be all and end all of how stiff a pole feels when you actually jump on it. Different brands are designed to bend in different ways, and different types of takeoff may find a pole responding in a different way. You could have two poles that flex the same when you hang a weight from the middle, but might feel completely different when a vaulter uses them. You can get a flex number on a crossbar, but you wouldn't want anyone to vault on it!

[KirkB]

... even from the same mfr, the weight rating is in 5 lb blocks, and so can mask up to a 4.5 lb difference in stiffness.

True, except for ESSX. ESSX is the only brand that uses 2.2 pound (1 kg) increments for its poles. I think this is a competitive advantage for them. The other mfrs don't want such a small increment, becuz that would mean more inventory, and buyers (coaches and vaulters) being more fussy on exactly what they want. They don't want every pole to be "special order" ... They'd rather just give you what they have in stock (at a retail outlet or at the factory) ... plus or minus 5 pounds.

For vaulters jumping under 3-4 meters, this is probably OK, but once you get into the Intermediate range (4-5 meters for men), then you NEED to be much fussier about the exact flex of your pole - even within each 5-pound range. However, even for a club, it's already difficult (and expensive) to try to fill in every 5-pound increment for every length of pole ... so it would be even more difficult (and costly) to fill in every 1 kg increment. Even as a parent ... like you ... this can get quite expensive, as your son or daughter grows quite quickly - physically and technically.

Jan's chart is based on the length of the pole, not the max handgrip, so thinking in your head that they are 11'8 poles is part of what is throwing you off. Max handgrip only applies to US high school vaulters, everyone else can and does ignore this.

That's right - you must refer to the physical pole LENGTH, not the GRIP you're using on it. And the max grip tape line on a pole is not part of the formula used on Jan's chart.

There's quite a few threads about this over the years. If you search for "bestflex", you might find some of those posts of interest ... and relevant to the problem/solution that we're discussing here. Basically, BestFlex was a proposal for a unified flex system for all mfrs ... proposed by Gill ... but it never caught on by other mfrs, so Gill dropped it. Not sure why, but I suppose it had to do with the other mfrs not wanting to comply with a system that was basically Gill's system - not an "impartial" system. Incidentally, Jan Johnson was a proponent of the BestFlex system, but when that proposal was no longer popular (it was actually only popular by Gill) then Jan devised his Relative Stiffness Chart.

Kirk

[superpipe]

You could have two poles that flex the same when you hang a weight from the middle, but might feel completely different when a vaulter uses them. You can get a flex number on a crossbar, but you wouldn't want anyone to vault on it!

Gill Sky poles and MF Rocket poles advertise they are made "for the high school vaulter" or "softer/slower" feel than Pacer FX and especially UCS poles of the same rating. This is fact when comparing by jumping on them and my educated guess on how they were engineered and manufactured. I would never compare a sky pole pole or rocket pole to a Pacer FX or UCS pole in terms of weight rating or flex number. Jan's chart is great, but you do have to be aware of the statements I made above. An extreme case is a training pole, which is practically a cross bar with a little extra. You sure wouldn't compare a training pole to a competitive pole in any manner, but the weight rating number wouldn't indicate that.

Standardizing a flex chart isn't going to happen and it shouldn't or pole manufacturers would be differentiating themselves by the stickers they put on their poles. The main difference between all poles and companies is the way they physically make the poles. Just because the flex number is the same, doesn't mean the pole will react the same as a different brand. This is recognized by rainbowgirl's referenced well-known saying "You can get a flex number on a crossbar, but you wouldn't want anyone to vault on it!",

As was already said, stick with one brand and model if you want the purest consistency across different poles. I guess there's the exception with the Gill flex chart change though.

Can you have an inventory of mixed brands and models? Sure, but be aware of the differences. I would only buy a different brand or model pole if the pole was such a good price, I couldn't let it go. That almost never happens.

[chasing6]

I have found that the 12'4 ESSX compare more closely with the (modern) 12'6 gill poles in terms of weight rating, not sure about the 12'4 Altius, I think they might be closer to the Gill 12' length.

I've used both, and you're pretty spot on RG. Treat ESSX like their longer cousins, Altius as their shorter. Since Altius poles tend to be a little softer and also have 4" less max grip than Gill, it works out pretty well.

[Divalent]

Thanks for all the comments. In distilling them all, I think I can figure out where I went astray: 1) using 11'8" as the length of the 130 skypole for comparison, rather than 12' (right there is nearly 2 poles difference), and 2) not knowing that the old skypoles were stiffer than equivalent versions today (by about a pole? I do now recall comments elsewhere regarding new labels for older poles that came back with higher weights).

So the universe is not nearly as fuzzy as I thought. The moral is to spend more time investigating.

(I still think a common standard would be very useful, even if, as others point out, its not the whole picture about what a pole is. But from the comments above it seems only one mfg really wants it.)

[KirkB]

I still think a common standard would be very useful, even if, as others point out, its not the whole picture about what a pole is. But from the comments above it seems only one mfg really wants it.

My guess is that Gill is the market leader, and the BestFlex system would have benefitted them more than their competitors ... entrenching them in their market-leading position. The smaller mfrs look for niches that they can exploit ... like ESSX using weight increments of 1 kg instead of 5 lbs ... and don't want to be tied to what would essentially be a Gill standard - not an independent standard. I realize that this isn't in the best interest of PV consumers. That's how I read it, anyhow.

Kirk

[Bruce Caldwell]

I still think a common standard would be very useful, even if, as others point out, its not the whole picture about what a pole is. But from the comments above it seems only one mfg really wants it.

My guess is that Gill is the market leader, and the BestFlex system would have benefitted them more than their competitors ... entrenching them in their market-leading position. The smaller mfrs look for niches that they can exploit ... like ESSX using weight increments of 1 kg instead of 5 lbs ... and don't want to be tied to what would essentially be a Gill standard - not an independent standard. I realize that this isn't in the best interest of PV consumers. That's how I read it, anyhow.

Kirk

I am for a universal flex chart. the best one to use is Earl Bell's where the 50 lbs weight is in the middle of the pole and the supports are 12" in on each side of each different length. SO why Have I not changed to his chart?
1. he has not made it available to me.
2. A change would require me for the next 10 years to put both his rating and mine on the pole to allow all to match ESSX pole out there in use as well as new ones.

The 1 kilo system works with 10's instead of feet! When computing Finite Element analyses to the pole 10 s programmed easier and gave us the most accuracy!
And it provides one the ability to buy or order a 120 other than sending you a 118 look at their metric number for a 118 pole they call 120lbs
with us you can get a 118-121-123-125-127-129-132 if you order a 120 we may send you a 121 or a 123
we just do not round it up or down it is what it is! 1 kilo equals 2.2 lbs 2 kilos is 4.4 lbs 5lbs has to be round up and down!!
The Butt Flex system was designed to measure the relative stiffness of the sail between poles. SO for it to be accurate one really must only flex that area usually from 6 inches up and as much as 161 inches. As different companies moved sails up and own the pole to get certain attributes and started using other material in place of the sail, the need for their brand to be measured farther up the pole than in the past.
With each company measuring based on their design , there is no way one brand can be equal to another!
Example on company has 175 inches as a span for 16'5" length pole while the other uses 169" and another 168"
So which is the best and the most accurate/
175 inches measures more of the top of the pole and area this company focuses on as important data for their pattern making.
(there 12.5 would be my 14.0 (est)) if I was to use the 175 inches to measure 16'5" ESSX poles the number would not be a relative stiffness even if the same due to exact design differences. The way their pole is made their flex works best and is most accurate for them, while to match their flex I would be about a 12.9 to match their 12.5. SO one would say hey I can jump on the 12.5 so it is stiffer I will use it instead of the 12.9 when the stiffness is just more in the upward portion of their poles compared to mine! To me it is a false reading , yet the way they are designed gives them a very accurate reading with their span!
I believe I have the best system for poles 13' down while Altius has a good system for their 12'9 poles, and at 14' they are all very similar on up. Spirit has a system that allows one to use the same span for 13' & 13'6" and the next span is used for the 14' & 14'6" and the next span for the 15' & 15'6" and just as we use the same span for 16' and 16'5"
So why do we all not get on the same band wagon? it would be better for the vaulter and coach yet matching poles would then be too easy?
I can say this all brand poles are weight rated similar and are within safe limits of one will use lbs when going from one brand to another!
Nothing more frustrating than one ordering a pole saying they want their pole to be stiffer than their white pole flex and that is nothing we can measure up to!
I do have a program that when you put in the Essx flex and power number into it, the program computes what the GFlex#, SFlex#.and the AFlex# on this pole!

The program also tells you what pole to go to on bad vault days called the " =2p" and what to go to when you need the next length pole called the "GO^2P" !
It should attach to this file
Sorry I could not attach the file those who wish the file can contact me at bruce@xlogicsports.com to receive it by email it is an excel file 2003 version and simple to use!

Hope you all enjoy it!
My donation to the Community!
Bruce Caldwell130