FLEX NUMBERS

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FLEX NUMBERS

New postby lonpvh » Wed Oct 09, 2002 7:18 pm

BRIAN, ITS ALL YOURS!!!!!!!!!!!!
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le' flex numbers'

New postby dubjones » Wed Oct 09, 2002 8:26 pm

Ok here goes!
For the sake of this, let's throw out weight, because weight equals a range of flex numbers. Say a 14' 150lbs could be a 21.0 to 20.0 flex (not accurate, I am not sure of the real numbers without my chart at work) so a 21.0, 20.9,20.8.....20.0 are all a 14' 150. Got it?
How do you get a flex number?
A specific distance for each length is set up and measured on a pole and the pole is hung on these points, then a specific weight is placed near the middle and the ammount of bend is measured, then the weight taken off, and measured again, the difference in these numbers, in cm, is your flex number. So if you hang a 14' pole, on these points, measure with and without weight, and the difference between these is 20.5, then the pole is a 14' 150, because it falls in the range of 21.0-20.0. Now, this is a bit simplistic, but the concept is solid. The stiffer the pole, the less bend with the weight, the lower the flex number, and stiffer the pole. So if you measured a 14' pole, and it comes out to a 19.9, then it is no longer a 150, it would fall into the next range of 155. Gettin' it?
Part of the trick.
If you have 2 14'150's one may be soft, say a 21.0, and another may be stiff, 20.0, so they are not the same pole. You in theory almost have a 14'145, and a 14'155, although they both say 150, and are 150's according to the range given.
Another part of the trick.
The span (or distance between points where the pole is hung) changes to accomodate the length of pole. Now not all manufacturers use the same span either. Some may use a slightly larger or smaller span, or measure the span closer to the top or bottom of the pole, or use a slightly different wieght, all slightly changing the flex, and possibly weight of the pole. So in essence a 14'150, 20.0 spirit may not equal a pacer 14'-150 20.0 essx, or the pacer 14'150 20.0 pacer, because they measure them slightly differently. ALL MANUFACTURERS ARE EXTREMELY ACCURATE AND CONSISTENT WHEN THEY MEASURE POLES! They just do it lightly different. I would not have any trouble telling someone to move from a 150 pacer to a 155 spirit or essx if he or she needed the next pole, they are that close.
At Bell Athletics we combat this problem by measuring all our poles ourselves to ensure that all things remain constant. That means we can ensure the numbers are always accurate same span, weight, ect. no matter what brand. Take for instance one of my poles, a 5.00m (16'-4") 15.9 (a 195 I think) carbon. Now from the factory it says flex 15.9, we measured it to be a 16.4 on our scale (because our span, weight, ect. is different than those at the gill factory, no better or worse, just different). But the pole smaller than it in my bag is a Gill number 16.4, our flex number was a 16.8. So I know no matter what color the pole was, that it is the next bigger pole for me. So if I blow through my (bell number) 16.8, I grab the 16.4 and all is well, it is .4 bigger, and I should jump higher.


Flex numbers are a more accurate measure than weight. They are a bit more tricky, but it may help you to figure out some problems in your series of poles. If you have weights that are close, it is possible to have flex numbers that are still quite a distance apart. As an expieriment you might want to check your bag, and check the differences in flex numbers. How much different in flex numbers is it from one pole to another. For my poles they go, as I go up poles, .6,.6,.5,.4,.4,.5,.4,.4,.5. Now these are small differences, I have several 180's,185's,190's,and 195's all 5.00m long. Differences for everyone else should be larger, my bag is overkill for most. Bigger jumps are OK. In your bag did you find any big jumps, or small jumps. That may explain why some poles feel way bigger, or just slightly bigger than others.
There is more to it than this of course, but this is a good overview.
Hope this helps.
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New postby Robert schmitt » Wed Oct 09, 2002 9:52 pm

Great explanation, I totally pick poles for my vaulters by flex #. I've noticed that some brands, the rated wieght for a flex # has changed over the past 10 years. So we have a brand new 155 that is the same flex number as a older 150 that we were borrowing. These were the same brands. So esp. in high school were you run into poles that you are using that may span 15 years it is REALLY important to understand flex # so as not to frustrat your self!
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New postby rainbowgirl28 » Wed Oct 09, 2002 10:19 pm

Robert schmitt wrote:Great explanation, I totally pick poles for my vaulters by flex #. I've noticed that some brands, the rated wieght for a flex # has changed over the past 10 years. So we have a brand new 155 that is the same flex number as a older 150 that we were borrowing. These were the same brands. So esp. in high school were you run into poles that you are using that may span 15 years it is REALLY important to understand flex # so as not to frustrat your self!


Oh yeah I know Altius poles are really different in the past 10 years... at King's we have a 14'170, that is definitely a 180 by their current flex charts. And of course Altius makes things extra fun by measuring flex numbers in inches instead of centimeters :P
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New postby Azbeachboy1 » Wed Oct 09, 2002 11:18 pm

wow!!! I feel like ive just been at school. That helped alot. It would be alot easier if we got all the pole brands on the same page so that they all tested them exactly the same. Any hoo, I guess thats why their different company's pulling in different profits.
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New postby lonpvh » Wed Oct 09, 2002 11:21 pm

Most of them are so close it doesn't matter, but it is the most important thing when chosing a pole. If you have a bad pole in your hands and all the practicing in the world won't make a bit of difference. Good luck with it, I suggest checking them if you havn't. Lon
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New postby PVJunkie » Thu Oct 10, 2002 12:14 am

Well........what more can be said. The lower the # the stiffer the pole, no 2 poles (made by the same co.) that have a different weight can have the same #, as best as i can tell UCS and Gill use the same weight and span to flex the poles but apply the weight a little differently.

As far as getting everyone on the same page (with the # to weight) there is a movement with the ASTM on pole vault safty to have it done. No telling when it might happen.

There are differences between brands. It has to do with the responsivness of the pole (amount of energy it gives back - return). In lab conditions the Pacer FX and the Spirit are almost identical and the Carbon FX returns more than any other. These studies were done with literally 100's of poles grouped so that they had the same length and flex #. The Skypole is a beginner to inermidate vaulters pole and is meant to return slower and less to aid in learning technique. But like Lon said its not the arrow its the indian. A stiffer pole is a stiffer pole, but the performace differences can skew just basing a decision on the flex #'s for the less consistant vaulter. Lon is a stud (even when the State fair rules are used) and could jump high on almost any pole. However, his timing is better served by a more aggressive pole.

Later, B
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New postby lonpvh » Thu Oct 10, 2002 1:11 am

Brian you are too kind. I think Dub is the little indian that could though. I wouldn't have it any other way with those state fair rules. LB
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New postby PVJunkie » Thu Oct 10, 2002 10:28 am

Come on now Lon.......I am not kissin your arse...........You are just that damn good (you would have to be, you beat me the last time we jumped against each other). A little ego fluffin goin on.

later, B
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New postby gpc3 » Fri Oct 11, 2002 7:53 am

Nobody has ever answered this satisfactorily for me. If you don't have the budget for an infinite number of poles, and you have to hold down 12" or 18" on a pole, obviously the flex # is not the same. Shouldn't you measure the flex at this point yourself? I know the 5 lb per 6" rule, but that doesn't really work in many cases, esp. when you get down to the 18" area. Shouldn't a 150 lb. HS vaulter be able to hold down on a 140 lb pole and still be legal? And what if a 120 girl can only half bend a 110 pole - why can't she use it? What if she stalls out on the 120 because it's too stiff for her? She gets rejected and hurt. This happened to us. Somebody needs to address the real safety issues here. Arrrgh.
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New postby rainbowgirl28 » Fri Oct 11, 2002 9:26 am

gpc3 wrote:Nobody has ever answered this satisfactorily for me. If you don't have the budget for an infinite number of poles, and you have to hold down 12" or 18" on a pole, obviously the flex # is not the same. Shouldn't you measure the flex at this point yourself?


Well most people cannot accurately measure the flex point themselves. Bell's is the only place I have ever heard of that remeasures their poles.

I know the 5 lb per 6" rule, but that doesn't really work in many cases, esp. when you get down to the 18" area. Shouldn't a 150 lb. HS vaulter be able to hold down on a 140 lb pole and still be legal?


Well like you just hinted at... the 10 lbs per foot is just an approximation. And the reason it does not work as well, the further you grip down the pole, is you have the sailpiece in the totally wrong position. Gripping down 2 feet on a 14'130, does not a 12'150 make.

So should high schoolers be able to grip down a foot and be legal for 10 pounds stiffer... aside from the sail piece issue, there is a practicality issue. You would have to have more markings on the pole, and it would be a pain for officials to keep track of stuff like that. Not saying it could not potentially work out... but it would not be as easy as it seems.

And what if a 120 girl can only half bend a 110 pole - why can't she use it? What if she stalls out on the 120 because it's too stiff for her? She gets rejected and hurt. This happened to us. Somebody needs to address the real safety issues here. Arrrgh.


My understanding of things... when they adopted the weight rating rule, the intent was NOT to get kids on stiffer poles and stalling out... it was to get kids on shorter poles that were not mushy, and landing safely in the pit! I have seen plenty of girls struggling to bend and get in safely on 12' poles at or above their weight...

Give 11' poles a chance! I set my best mark during the high school season my senior year (9'9") on an 11'140. When the 12'120 and 130 I ordered finally came in, I was very excited to use them, but I never did go as high on them until several months later.

Yeah I know things are not as simple as all that. With proper coaching, kids can safely vault on poles well under their weight. With improper coaching kids can vault very unsafely on poles over their weight. But this is the way the rules are right now. And trust me there is not enough agreement on if/how that rule should be changed for any changes to happen anytime soon. Apply the rule the way it was meant to be applied! Shorter poles.

Yeah it does suck to be a high school with a limited budget and few poles. Be creative! Get your vaulters to do fundraisers. Buy cheaper poles! I don't like to use Altius poles... but they make great beginner poles and they are dirt cheap. Out in the NW, Tim Reilly sells them for hundreds less than their Spirit/Pacer counterparts. And he sells them buy 4 get the 5th free. Someday I will be coaching, and I would much rather have a nice pole ladder of Altius poles than a couple nice Spirits. Work with other schools... trade/share poles. If a pole is too small and you don't have anything bigger, move the kid into a shorter run. I am sure there are lots of other ideas out there!

What are the real safety issues? I feel they lie less in the rules and more in how the rules are applied.
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New postby gpc3 » Fri Oct 11, 2002 11:48 am

ANYONE can do flex numbers. Jan Johnson sent me the criteria. You just place a pole on two braced hurdles at specified points and hang a 50 lb weight midway. Measure the cm deflection from the no-weight position and you have it. We did that for all our poles and found some huge discrepancies that supported our own doubts about some poles' ratings. Then we moved the hurdle in 6" and then 12" and 18" and did the tests again. It's not very scientific, but now at least we know how stiff each of our poles are at those points.

As for a 11' pole, the girl blew through the shorter pole because of her runway speed. She needed a 12' pole, but the one rated at her body weight was too stiff. She was just right at a lighter rated pole, but it was illegal for competition. I think that pole vaulting will die out, because the rules we have now do very little to prevent the injuries and deaths that have occured recently. The Penn State death happened with a very knowledgable coach and athlete in a totally supervised environment. Bad things happen sometimes. It's a risky sport. So is football, so is gymnastics, so is cheerleading. Cheerleaders and cross country runners lead all injury categories. We must be prudent, but we cannot legislate that no one will get hurt. Coaches must have training and be certified or their athletes shouldn't vault. Must vault coaches ARE knowledgable, or they wouldn't be there in the first place.
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