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Re: pole transitions (grip)

Posted: Sun Aug 16, 2015 1:35 am
by KirkB
Skyfly, I hear you on all this (and Kyle too). But without a length/flex chart, I don't see a current alternative to the length/banana chart (aka length/weight chart). We can diss the current system all we want, but there needs to be a better, more viable alternative before we discard it.

Back in the day, I measured my own flexes on my Catapoles, to double-check the flexes provided by Catapole. And yes, since the poles were all 16 feet long, and all the same brand, I could have just trusted their flex #s scratched onto the poles. But I wanted to be POSITIVE that the flexes were as identified.

I'm not suggesting that every vaulter do the same, as this seems like far too much work (and potentially unreliable) for the average vaulter, but I trusted my own measurements more than the mfr's.

I seem to recall someone saying something about an independent testing organization considering providing the flex tests. Was that ASTM? Since each mfr seems to be unwilling to do this themselves (for competitive or confidentiality reasons, or whatever), then it does seem like a good idea to have an independent testing body conduct tests for each brand of pole. Then a chart of lengths/flexes could be built, that's agnostic to pole brand.

Sidebar: For American high schools, the standards used to be allowed to be set at 0". They now must be set within the range of 15.5" to 31.5". This was a good rule improvement, but I don't think it went far enough. I would suggest at least a 20" minimum. That would be a good rule improvement to reduce stall-outs. Also, there outta be a rule about landing in the PLZ (Preferred Landing Zone, aka Coach's Box). If you miss the PLZ, that's counted as a miss, even if you clear the bar! :idea: But that's another story for another thread. To improve vaulter safety, one or both of these 2 suggested improvements might be better than the existing HS weight rule. Just an idea. :idea:

Kirk

Re: pole transitions (grip)

Posted: Sun Aug 16, 2015 3:31 pm
by grandevaulter
Standards have been 18" and 31 1/2" for a few years now Kirk.

Re: pole transitions (grip)

Posted: Sun Aug 16, 2015 4:01 pm
by KirkB
Sorry, I must have gotten the 15.5" from an obsolete rule book. Thanks for the update.

Here's a good explanation of this rule, from the PoleVaultCity website:

http://www.polevaultcity.com/2012/08/22/nfhs-rule-7-5-19-changes-standards-limits/

New limits on standard settings will be in effect for the 2013 track season. The National Federation of State High School Associations has moved the front end limit of the standards from 15.5″ back to 18″ in an effort to increase the safety of the pole vault. ...

Kirk

Re: pole transitions (grip)

Posted: Thu Aug 20, 2015 10:12 pm
by Skyfly
Although not particularly relevant to the original discussion, I have an obscene amount of data regarding flex numbers that I collected over the last couple of years. As an engineer, data fascinates me... maybe it does you too.

One thing I find interesting is that Gill treats the flex and rating of a pole the same across all the models (not sure about the Pacer ONE, but I am assuming that would be true as well). Kind of another reason why even flex numbers aren't really the best way to go about rating a pole. Differences in construction and materials to me would mean that poles of the same flex but different models should yield a different capacity and thus different rating. I think an obvious example of this is mentioned in Alan's BTB book. You get a piece of PVC tubing and flex it and then compare it to a pole of the same length and flex, well I think you get the idea that they are most assuredly not equal

Anyway, what I have found is that for Gill each series of poles has a completely linear correlation between flex and weight rating. Spirit however has a mix of some series being linear, while others are an exponential correlation so as the poles in the middle of a series are close to linear but poles of the lightest weight have a greater step between each weight and poles of the stiffest weight have a smaller step between each weight. Also interesting that for 13' and 15' poles Gill and Spirit are basically identical for flex/weight correlation. Other series aren't remotely close. I don't think this is surprising given the fact it's fairly well known that Gill and Spirit flex the half foot series in different ways, but the 14' series is completely not aligned either. Even in the 15' series for Spirit, the linear correlation matches Gill, but the data when plotted is quite obviously exponential. So basically Spirit and Gill roughly match at the middle weights, but not the lightest and heaviest.