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I know the rule of thumb for pole wieghts equiv. when switching from a 14 to 15 foot pole per say. I was wondering since I perfer to use flex #'s is their a rule of thumb for a flex # increase for going to diff. pole lengths? for example (I'm just pulling these # out of the air) if I have a kid jumping on a 13' 20.4 flex what flex # would be equivalent holding at the same hand grip on a 13'6" and 14' pole?

Good question Robert.
I will take a stab at it because I know the Gill guys on the board will gladly correct me if I'm wrong.
13-20.4=13'6"-22.8=14'-25.7
This was based on beam deflection varying with cube of the length.

wow - if you want a simple this will always work rule stop reading - how about some guidelines and approx. - If you have a 13' pole and now want a 13'6" pole where if you hold the same hgt as on the 13 - your get the same flex - what should the 13'6" flex rating be - about 2 cm softer or higher - i.e 20.4 - would want about a 22.4 - the problem being it does not hold absolutely true everywhere in transitions - also the further down you hold changes the amount the flex changes - this is also why cutting down poles gets tricky - since the E and I of the pole vary throught the length - thats why I am skeptical of anyone who cuts a few inches off a pole because it makes it work better - maybe they just need the right length and wgt to start with - the rest is as much a placebo effect as anything else - now this could probably start a heated discussion but - ow well - once you are in a pole length the transitions are easy - it is jumping or changing length that make it interesting

Why do engineers make things so hard to understand!!!!!!!!!

Basically what Jeff is saying here is there are way too many variables to have a good firm rule of thumb for flex #'s of different length poles. This is because if a 13 20.4 is a 13'6" 22.4 it does not mean that a 13 18.4 is a 13'6" 20.4 it may only be 1.8 different. In any given length the wt rating is a range of flex #'s that is why the up 6" back 5# you have the next stiffer pole is good, it allows for some wiggle room. If you truly need something that accurate (which in most cases will fall in line with the up 6 rule) call the manufac and ask them to test something close to what you have and recommend the flex at the next longer pole.

yeah thats exactly what I said kinda - by the way - he did not take me up on the 400 - 6 inches a year and he would probably still beat me in the vault - maybe not - but he did bet a beer on todays vault practice - taste good already - by the way - that only holds true if you stay with the same pole manufacturer - since not everyone flexes the same - the numbers do not always match up

Thanx

The reason I asked this question is last year we had to borrow a lot of poles. I noticed we were in particular borrowing a 12'4" Altius 5.9 flex. (They do everything in inches for some god fore saken reason) pole. I've seen this same flex number pole given three wieght classifactions depending on when it was made I've seen it as a 12'4"150 a 12'4" 155 and a 12'4" 160 all being a 5.9 flex obviously they have changed thier flex charts over the years. anywho, since I inherited all these altius poles when when I move my vaulter to a 13' pole I really don't know what I'm getting by looking at the wieght rating(since I've seen three identical flex# poles given diff ratings) so I would like to use the flex#.

to convert to metric you take the english flex number and mulitply x 2.54 and you get the metric number.

Altius is a good pole you might call Paul and talk with him about this and get some info so you can move from one to another!
1-800-374-7653

Altius can be strange sometimes. I know my high school had a few poles that have a stiffer flex number then the one that is five pounds above it.

Yeah I am pretty sure Altius adjusted all their poles by about 10 pounds a few years back... my high school's 14'170 is now a 14'180 by their current flex charts...