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Author Topic: Sidecut??  (Read 1401 times)

byronm

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Sidecut??
« on: January 03, 2013, 08:43:13 pm »
Hey Folks,
 
In the vein of continued education and forgive the ignorance. Can someone explain or point me to a resource that explains how "sidecut" is commonly determined. I hear many references to sidecut and "I think" generally understand the concept, but wondered if there is a "standard", a specific number and how that number is calculated?
 
For example, I know my ski dimensions are 124-76-107. I assume that as the shovel and tail get wider in relation to the mid section of the ski, it has "more sidecut".
 
So if I were to say, my skis have X amount of sidecut, how would I calculate and articulate that?
 
On a traditionally shaped ski, is there a standard correlation between sidecut and "turn radius" or is that "way in the weeds"?
 
I know there are a "ton" of variable ski shapes and...well....varia bles. Just wanting to get a "semi-basic" understanding so that I can follow some of the dialogue better in the forum, escpecially as they relate to ski reviews.
 
Thanks a bunch.......
« Last Edit: January 03, 2013, 08:46:16 pm by byronm »
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jim-ratliff

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Re: Sidecut??
« Reply #1 on: January 03, 2013, 09:15:37 pm »
Average the front and rear width, subtract the waist width, and divide by two roughly yields the sidecut.

For your 124-76-107 the sidecut would be about 19mm? (The depth of the cut on each side.)

Sidecut correlates to sidecut radius, but a 180cm ski with 20mm sidecut will have a larger sidecut radius than a 160cm ski with the same sidecut. I'm not sure if "turn radius" differs from sidecut radius, but I think it includes the effect of bending the ski.
« Last Edit: January 03, 2013, 09:32:51 pm by jim-ratliff »
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byronm

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Re: Sidecut??
« Reply #2 on: January 03, 2013, 09:21:35 pm »
Thx Jim......excellent explanation, I did the exercise and came up with 19.75....!! +1 more thing I learned here at Peak Ski.... :D
« Last Edit: January 03, 2013, 09:28:20 pm by byronm »
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HighAngles

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Re: Sidecut??
« Reply #3 on: January 04, 2013, 10:13:26 pm »
Here's what I use (it's the FIS method):

http://www.fis-ski.com/skicalc_info.htm

And here's a nice online calculator they make available:

http://www.fis-ski.com/skicalc.htm

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epic

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Re: Sidecut??
« Reply #4 on: January 05, 2013, 04:54:54 am »
Do all of that and then fudge it a little bit. That's what the manufacturers do. They'll publish the number of what teh sidecut "feels like" to them. It's usually pretty close to what is real.
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byronm

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Re: Sidecut??
« Reply #5 on: January 05, 2013, 05:09:22 am »
Way cool HA....makes the process a breeze. Ah....kind of like manufacturer mpg...."estimates" eh Epic?
 
I played with the calculator a bit and it seems as if it would take moving the midpoint forward quite a bit to manipulate actual turn radius, whereas I hear folks referencing fore/aft adjustment quite often for more or less tip engagement. Would I be correct to say that the turn radius may not vary much at all with forward adjustment of mid point mount but the initiation of the turn would/could be affected substantially?
 
Thx for the great info.....
 
p.s....couldnt get the first link to work for me, calculator came up fine tho.
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HighAngles

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Re: Sidecut??
« Reply #6 on: January 06, 2013, 03:25:20 pm »
Not sure why the first link is not working now, but here's the info:

Sidecut Radius Calculation

Ski length

To control the ski length, the developed length (flat material length) is used.

Sidecut radius

The rear and front ski lengths are measured starting from the narrowest point of the ski. In order to avoid that the entire side cut radius becomes distorted by the different geometries of the tail and tip, the rear ski width is recorded at 90% of the measured rear ski length whilst the front ski width is recorded at 80% of the measured front ski length.

The length is measured using a measuring tape with a precision of 1 mm. To avoid rounding differences the width can be measured by using calipers providing a precision of 1/100 mm. Width values S, H and W will be rounded in accordance with standard commercial practice to 1/10 mm and R is calculated with rounded values.



LTOT, LW, LS, L1, L2, S, H and W must be or are given in millimeter (mm).

The side cut radius R is calculated by using the following formula:

LH = LW * 0.1

L1 = (LTOT - LW) * 0.8

L2 = LW * 0.9

LS = L1 + LW

L = L1 + L2

R =    L2
2000 * (S + H - 2 * W)


R is given in m.

If the side cut radius lies below the valid limit set by the rules after the first measurement, the measurement including the calculations must be repeated three times. The arithmetic mean XR calculated from these three side cut measurements. To account for measurement errors in the length and width, the side cut radius is recorded as 1.015 XR. This figure will reflect a measurement error of 1.5% on average. 1.015 XR must be greater than or equal to the valid radius limit set by the rules.

Since the formula of the existing measuring method intends to reflect the unadulterated (undistorted) measurement of a side cut radius, this assumes that a continuously differentiable and monotonously curvedradius shall be maintained between point "S" and point "H", i.e. without any turning point in-between those two points.

In order to reflect the above, it is clarified thatthe radius determination assumes that:

At any point on the distance from W to H the width has to be smaller than at H.

At any point on the distance from W to S the width has to be smaller than at S.

If any of the above assumptions are not fulfilled, the concerned ski cannot be found as conform to the specifications.
« Last Edit: January 06, 2013, 06:50:50 pm by HighAngles »
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byronm

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Re: Sidecut??
« Reply #7 on: January 06, 2013, 04:59:13 pm »
Alrighty then......OK...so now I feel like Penny on the Big Bang Theory..... :o
 

This will take some pondering to get my head wrapped around....but I will.....I think....I might....well maybe.... :-X
 
Yo...Sheldon....Hel p!! ;D
« Last Edit: January 06, 2013, 05:01:43 pm by byronm »
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jim-ratliff

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Re: Sidecut??
« Reply #8 on: January 06, 2013, 05:05:52 pm »
Ditto!
Buzinga?
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HighAngles

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Re: Sidecut??
« Reply #9 on: January 06, 2013, 06:49:04 pm »
I just noticed that if you click on "Info" (lower right corner) on the online sidecut calculator it will successfully bring up the info page.
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byronm

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Re: Sidecut??
« Reply #10 on: January 06, 2013, 09:00:11 pm »
Quote
method intends to reflect the unadulterated (undistorted) measurement of a side cut radius, this assumes that a continuously differentiable and monotonously curvedradius shall be maintained between point "S" and point "H", i.e. without any turning point in-between those two points.


This is either Greek or Frank Zappa wrote it while pondering Dweezle and Moon Unit....not sure which..... :-X
 
For now....I'm gonna gloat over successfully completing exercise #1...(Fw+Rw/2 -Mw/2 = SC [apprx.])....... 8)
 
Because the other stuff  makes my brain hurt... :-\   
As evidenced by the premature greying and thoughtful wrinkles in my forehead... ;D
« Last Edit: January 06, 2013, 09:22:12 pm by byronm »
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HeluvaSkier

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Re: Sidecut??
« Reply #11 on: January 14, 2013, 08:50:13 pm »
Something to keep you guys entertained:

http://www.softpedia.com/get/Science-CAD/snoCAD-X.shtml
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Gary

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Re: Sidecut??
« Reply #12 on: January 15, 2013, 08:38:28 am »
I'm working on a geometric calculator that will help a person find their optimal significant other...

Ya just plug in all their physical dimensions and out comes their physiological sidecut....yup,....easypeezy!

How that person turns, floats, drifts, carves in all sorts of social interactions not to mention the perfect ski mate!  :o

Of course I'd have to also consider their alignment, tracking and fore/aft balance into the equation....but heck....there's a bunch of smart guys here.....no prob!  ::)

Yeah....we could make a trillion!   8)

g
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jim-ratliff

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Re: Sidecut??
« Reply #13 on: January 15, 2013, 09:09:40 am »
so 36-24-32 is a "physiological sidecut".    :-\  hmmm.


So, Gary, what do you normally ingest for breakfast??
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Gary

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Re: Sidecut??
« Reply #14 on: January 15, 2013, 09:27:26 am »
Ha..Jim...that would be a good start but sooooooooooooooo many other factors.....as we both know!

As far as what I ingest in the morning.........A good dose of humor topped off by a heaping helping of balance!  :D

G
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