sduvinage wrote:Can someone explain to me why two poles of the same weight can have a different stiffness to it?
Is this even true?
I thought the weight rating of a pole was directly related to its flex rating?
Within a specific brand, there is a range of flex numbers that correspond to a weight rating for a given length (it's different for every length).
A 13'150 might have a flex a between 18.5 and 19.0 (I just made up those flex numbers). So a 13'150 might really be a 13'150, 13'151, 13'152, 13'153, or 13'154. Although the manufacturers have patterns they cut the fiberglass in to achieve a pole of a certain weight rating, it can be difficult to get them to come out the same every time for a variety of reasons. They might try to make 10 18.8 poles, and maybe 5 come out as 18.8 and the rest in that 18.5 to 19.0 range. It's especially difficult the smaller the pole gets, that is part of the reason you see the smaller poles in bigger weight increments.
This is a generalization, the flex number to weight ratio also varies with the length and stiffness of the pole, so in the really small poles, 1.5 of flex might translate to about 5 pounds, while in a medium sized pole, it might be 1.0, and for the poles the elites are on, it might be 0.5 or less. Again, those are generalizations to give you an idea, not actual numbers.
Different manufacturers vary in the spans they use to flex their poles, so their numbers are generally not comparable. They each use their own flex number scale to assign a weight rating (because there is more to the resistance you feel than flex numbers, for example, a crossbar has a flex number, but you wouldn't want to vault on one if it was bending more than a tiny bit).
So Manufacturer A might say a 13'150 is anything between an 18.5 and 19.0. Manufacturer B might use a different span, but if their 13'150s were tested on the same span as Manufacturer A, you might find that theirs were between 18.7 and 19.2, and manufacturer C might come out like 18.4 to 18.9.
Studies have been done and it was found that for most poles, you're going to get a similar pole if you order by length and weight rating no matter who the manufacturer is.
But flex numbers do matter, that's why it is important to use them when ordering new poles of the same length as existing poles. I always recommend coaches stay within the same manufacturer if most of their poles in a given length are already the same manufacturer.
For example, in the 12' to 12'4 length there is a lot of variation.
Gill (Skypole/Mystic/Pacer) makes 12' poles in 5lb increments. But in 2003 they tinkered with the flex charts, so an older 12'120 may feel more like a 130. And they didn't always do 5lb increments.
Spirit makes 12'1.5" poles in 10lb increments. So a 12'120 Spirit has a bigger range, it could be as soft as a soft Mystic 12'120, or as stiff as a stiffer Mystic 12'125.
Altius makes 12'4 poles in 5lb increments. I haven't used them much, especially not any made in the past 10 years, so I can't say how they compare.
ESSX makes 12'4 poles in 2kilo increments. In my experience, their weight ratings probably compare a little closer to Gill's 12'6 poles than Gill's 12' poles.
On the other hand, the 13' length is more similar between all brands, everyone is between 13'0 and 13'3 and does 5lb increments.
It's also important to note that the pattern of the pole also influences how stiff it feels. You might have a Spirit, Altius, ESSX, Skypole, and CarbonFX that were all the same length and same stiffness when flexed, but some of the poles may "feel" stiffer to the athlete depending on the style of their jump. Some poles are more forgiving of a bad takeoff, others may unbend a little quicker at top.
Also, most athletes do not perform the same way each jump. If an athlete believes they are jumping on a stiffer pole, they may try too hard and find the pole to be MUCH BIGGER when the real problem is their takeoff fell apart.
), the WEIGHT of a pole is an approximation of how stiff it is ... whereas the FLEX of a pole is a more precise measurement of its stiffness. So for each pole of a certain weight and length, there are several flexes. The flexes are just smaller increments than the weights.
