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Looking for a really smart skier or "Can you trust ski company's figures" !

#1
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10/7/09 at 4:20pm
  • Joined: July 2009
  • Location: Sangrila
  • Post Count: 24
I consider myself an educated skier who has "tested" many skis over the years. I read all about skis and their performance specifications, not only from magazines, but ski company technical data This "problem" has me stumped,,so I am looking for a wiser skier!

I have two 2010 skis from same ski company , let us call them A and B. Both are same length,,that is 175 cm.
A has the following "profile"; tip 117mm.  waist 65mm.  tail 101mm.  with a stated radius of 14.5 meters
B has the following "profile"; tip 116mm.  waist 66mm.  tail 101mm.  with a stated radius of 16.2 meters

I have done a static bench test of the tip and tail flex using a 1kilo dead weight. Both are equal.

Look at what 1mm. is! How can 1mm. difference at tip and waist result is a 2.3 meter difference in radius curve?
I contact the engineers of this company and they confirm the figures, but will not give me explanations or reasons why!

Looking for really, really smart skier/scientist who can explain this!

I suspect an error!
I will be testing these two skis soon on the slope,,so will see if turning is different!

Have ski, will travel

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#2
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10/7/09 at 4:36pm
  • Joined: November 2004
  • Location: Kentucky for 43 weeks-skiing for 9 !
  • Post Count: 2,263
Try putting an average persons body weight on each ski as a bench test and see how much each flexes. It's the shape of the ski tipped on it's edge that will determine the radius.

Stiffer ski  =   less flex (bow shape)= longer radius.

Softer ski  =   more flex  = shorter radius.

Torsional stiffness will also be a factor.

Unofficial,  but my view on the deal.
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#3
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10/7/09 at 4:40pm
  • Joined: October 2005
  • Location: Tahoe
  • Post Count: 3,105
Or..........you could uhmmmmm.........ignore the numbers and just go ski.

Just a thought...................

SJ
www.starthaus.com   (Check out SH ski deals #2 in the special deals forum)
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#4
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10/7/09 at 5:01pm
  • Joined: July 2009
  • Location: Sangrila
  • Post Count: 24
Thank you for the two prompt replies.
I tried the "formula" posted on this site and did some "projections" using all the data I had on all the ski companies skis! They are way way off or the formula is incorrect!  I will stick by formula since I have been using it for some time! and it was confirmed on slope!
I am aware of the flex and torsion issue! They are the same for A and B!
Sierra Jim is on right track! It is what the skis do on the slopes that makes the difference!!!! The proof is in the pudding! Old saying but very valid!
Yet I see so many  "skiers" quote this or that figure to proof THEIR ski is better!

Have ski, will travel

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#5
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10/7/09 at 5:13pm
  • Joined: August 2009
  • Post Count: 49


Quote:
Originally Posted by skigypsy View Post

Yet I see so many  "skiers" quote this or that figure to proof THEIR ski is better!

You must hang out with a different crowd than I do...
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#6
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10/7/09 at 5:16pm
  • Joined: October 2003
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-

Edited by comprex - 10/8/09 at 5:17am

Now on Mondays.

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#7
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10/7/09 at 8:36pm
  • Joined: October 2005
  • Location: Tahoe
  • Post Count: 3,105
PLEASE!!

Do not forget to multiply by the cube root of Pi. Then equally importantly, deduct the number of days skiing from from the average of the days/month of skiable snow for the season (regionally of course) from the resultant of the prior calculation. Then consult the Mayan calendar and find the date of the vernal equinox, take that date, divide by 3.7 if above the equator or 4.2 if below. Multiply that result by the rotational speed of Venus on March 16 2014 and take the result of that, and divide by two.

That'll getcha there!!

SJ
www.starthaus.com   (Check out SH ski deals #2 in the special deals forum)
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#8
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10/8/09 at 4:54am
  • Joined: July 2009
  • Location: Sangrila
  • Post Count: 24
Sierra Jim has a point!
I will just get on slopes and see what those skis can do!
However it does put into question all that data you read on marketing literature and all those "ski evaluation" projects !
Keep you posted.

Have ski, will travel

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#9
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10/8/09 at 5:09am
  • Joined: December 2008
  • Location: Somewhere between manic and depressed
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Quote:
Originally Posted by SierraJim View Post

PLEASE!!

Do not forget to multiply by the cube root of Pi. 
...

That'll getcha there!!

SJ
 
SJ, you must not have been listening to the folktale math wisdom in the hallways of your high school...everybody knows that, if you multiply by the cube root of pi, you die.

This thread makes me think of the "dual radius" Fischer Progressor skis...the radius is supposed to be different depending upon how much you tip and bend the skis.
Skigypsy, if you stack the skis, does the outline look any different? Are the tips/tails "longer" on one than the other?
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#10
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10/8/09 at 5:45am
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  • Location: Massachusetts
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 Actually the Progressor's radius is not different "depending upon how much you tip and bend the skis"  it is different in front of the bindings then behind the bindings, thus a different radius at the top of the turn then at the bottom of the turn - according to their literature.
We are all the same distance from infinity.
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#11
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10/8/09 at 6:28am
  • Joined: December 2008
  • Location: Somewhere between manic and depressed
  • Post Count: 396
Oops...I appreciate the correction.

Quote:
Originally Posted by SkiMangoJazz View Post

 Actually the Progressor's radius is not different "depending upon how much you tip and bend the skis"  it is different in front of the bindings then behind the bindings, thus a different radius at the top of the turn then at the bottom of the turn - according to their literature.


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