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Ski sizing for the modern age- should your jacket size be your ski size? - Page 2

post #31 of 53

Just added a couple of new data points to the survey (but not to the chart, until the OP pulls them in). I expect I'll be in the upper left of the green box. I definitely use the size range offered in a particular model as a primary point of information in my choice of length. The phenomenon of "only three sizes" seems new to me, or maybe it's because historically I have looked mostly at narrower skis, which often come in more lengths ???  In any case, I have found that at 5' 7" 135lbs, if the mfr. offers 4 sizes (e.g., Blizzard. Armada), I almost invariably fit very nicely on the #2 size. In cases where there are 5 sizes (e.g., Dynastar, in the past), it's a toss-up between #2 and #3. Where there are only 3 sizes, it's again hard choice between #1 and #2. This maps just about exactly to my clothing situation. For brands that have 4 sizes, I'm always #2 (S, if XS-S-M-L; or M, if S-M-L-XL), but if if 5 or 3 sizes, where I take a S in many brands and models but a M in certain others. Bottom line to manufacturers: Please offer four sizes so I know which one to get! :)

post #32 of 53

That chart should be normalized for running length of skis.

post #33 of 53
Thread Starter 
Quote:
Originally Posted by Ghost View Post

Perhaps you can explain to me how this chart works then.  I'm 160 lbs, skis are 165 (sl ish), 188, 190 (GS ish) and 208 cm (Super G).  I don't see any corresponding polygons on the chart.

The chart works relative to the ski sizes offered in that particular model.  A 180 on-piste carver is targeted to a very different size of a skier than a 180 rockered soft powder ski.  The chart also does not work for older skis that were meade ina  bunch of lengths.  It should work best for newer model freeride skis that are often made in 3 lengths (maybe 4 length with the 4th that you would call either XS or an XL).   

post #34 of 53
Thread Starter 
Quote:
Originally Posted by PlugBootBlues View Post

That chart should be normalized for running length of skis.

No!  The idea is that the manufacturer should do that for you when they pick what sizes to make.  

post #35 of 53

So then for slalom skis, a small would be 155, a medium 160, a large 165, and an XL 170?

 

And then for GS, small would be 177, M 183, L 188, and XL 193?

post #36 of 53
Thread Starter 
Quote:
Originally Posted by voelfgar View Post

Agreed.

 

I do predictive modeling as part of my job, so I could throw the data into my high end Statiscal software package and do some clustering

voelfgar, PM me your E-mail.  There is only about 60 data points on the chart and many of them come from the same skiers, so we will need more data to make any reliable conclusions.  The irony is almost any ski shop sits on a treasure trove of this inormation- the shop mounting forms typically have the height, weight, make/model of the ski, ski length and the skier type, and I bet a good shop mounts hundreds of skis in a season.  That way you'd bias he data to newer skis automatically.  I'd bet that the chart with data from a  shop like REI will very closely correlate with height, and data from a high-end mountain-town shop like Starthaus will be much more weight-biased.  

 

If any shop is willing to share that data in an anonimized fashion (i.e. we don't need to know the names, addresses, etc., and the shops need to protect their client privacy, so someone would still need to look through the forms and compile the data.  We don;t even need the names of the skis, just the SX-S-M-L-XL size relative to lineup) I'd love to get my hands on them.  

post #37 of 53
Quote:
Originally Posted by alexzn View Post

Quote:
Originally Posted by Ghost View Post

Perhaps you can explain to me how this chart works then.  I'm 160 lbs, skis are 165 (sl ish), 188, 190 (GS ish) and 208 cm (Super G).  I don't see any corresponding polygons on the chart.

The chart works relative to the ski sizes offered in that particular model.  A 180 on-piste carver is targeted to a very different size of a skier than a 180 rockered soft powder ski.  The chart also does not work for older skis that were meade ina  bunch of lengths.  It should work best for newer model freeride skis that are often made in 3 lengths (maybe 4 length with the 4th that you would call either XS or an XL).   

Yes, I see that.  What I don't see is why there isn't a data point or three at 160 lbs, if the data from the survey are supposed to be on the chart ( e.g. small blue triangles at (160, 165) and (160, 188) )

post #38 of 53
Quote:
Originally Posted by Ghost View Post

Perhaps you can explain to me how this chart works then.  I'm 160 lbs, skis are 165 (sl ish), 188, 190 (GS ish) and 208 cm (Super G).  I don't see any corresponding polygons on the chart.

 

Not sure what to tell you, alexzn can hopefully clear that up.  I do see polygons that appear to coincide correctly with the data I supplied in the survey thread.  So I assumed they were me.

post #39 of 53
Thread Starter 
Quote:
Originally Posted by Ghost View Post

Yes, I see that.  What I don't see is why there isn't a data point or three at 160 lbs, if the data from the survey are supposed to be on the chart ( e.g. small blue triangles at (160, 165) and (160, 188) )

I looked again, and I think the reason your data are not on the graph is that (a) I could not find the sizing for the skis that you have. Also, (b) I think P50 is a relatively old Volkl ski  (ca. 2000 model) and I also recall hat McConkey was making Volant Machete commercials in early 2000's.  I am sure Machete were great skis and still are, but ski designs evolved since those times and I wanted the chart to reflect the current thinking of ski designers and consumers.  Also, the chart is oriented towards recreational freeride skis.  Racers know their ski size and are rarely confused about it.  No one asks here on Epic- I just won the GS competition in my age group... so, in what size should I get my new racing skis?

beercheer.gif.

post #40 of 53
Quote:
Originally Posted by alexzn View Post

Quote:
Originally Posted by Ghost View Post

Yes, I see that.  What I don't see is why there isn't a data point or three at 160 lbs, if the data from the survey are supposed to be on the chart ( e.g. small blue triangles at (160, 165) and (160, 188) )

I looked again, and I think the reason your data are not on the graph is that (a) I could not find the sizing for the skis that you have. Also, (b) I think P50 is a relatively old Volkl ski  (ca. 2000 model) and I also recall hat McConkey was making Volant Machete commercials in early 2000's.  I am sure Machete were great skis and still are, but ski designs evolved since those times and I wanted the chart to reflect the current thinking of ski designers and consumers.  Also, the chart is oriented towards recreational freeride skis.  Racers know their ski size and are rarely confused about it.  No one asks here on Epic- I just won the GS competition in my age group... so, in what size should I get my new racing skis?

beercheer.gif.


So you pre-whitened the data to make it show a foregone conclusion.  wink.gif.

 

Relax, I'm just Joshin you.  smile.gifbiggrin.gif

 

I am a recreational skier, not a racer.  I can only admit to racing my buddies.  Lots of recreational skiers use racing skis for fun.

 

The P50s and Machete were 2002 models, but bought much later (the P50 in '08) new in plastic.  there's still a good market for the Volants on E-Bay. 

I agree with taking the speed skis off the menu, and maybe these don't need to be there either, but where's the Fischer WC SC?  For what it's worth, except for the speed ski, the remaining points pretty much fit the blue box.

 

Just in case anyone's interested, SG came in 205, 208 and 215, (and maybe 220; I only tested the 205, 208 and 215).

The P50 F1 Energy came in 168, 173, 178, 183, 188 and  193

The Machete came in 70, 175, 180, 185, 190

The Fischer WC SC came in (and still comes in, but now SC Pro)  150,155,160,165,170

 

I'm a medium, with a bias towards large; second from the top seems to work out well for me; I would probably be happier with a 185 Machete (that's all they had and for $99.99, I couldn't resist).

post #41 of 53

Oh my god....need...to....ski....eek.gif

post #42 of 53
Thread Starter 
Quote:
Originally Posted by Ghost View Post

The P50s and Machete were 2002 models, but bought much later (the P50 in '08) new in plastic.  there's still a good market for the Volants on E-Bay. 

I agree with taking the speed skis off the menu, and maybe these don't need to be there either, but where's the Fischer WC SC?  For what it's worth, except for the speed ski, the remaining points pretty much fit the blue box.

Yepp, even if you bought them new in 2008, they are still the 10-year old ski designs today biggrin.gif.  I am surprised that you fit the rule, I think in those days ski sizes were a lot more height-biased, had somethign to do with technique evolution (see my answer to Noodler).   Cheers!  

 

P.S. Volants are the only skis that are supposed to last forever!  I am not a big fan of the Machete commercial, but here it is for the fans:

post #43 of 53

Interesting theory!  According to the chart, I am above the "small" box (higher Y axis value) and also with a lower X value than the "medium" box.  I always ski the "medium" size if 3 sizes are offered.  Usually the 2nd largest size if 4 sizes are offered, unless the ski is stiffer than usual.

 

I think that skiing ability would be the next paramater that needs to be analyzed.  Along with that, it would be an terrain situations that would call for a ski out of the "normal" size: big mountain terrain where a 190cm+ comes in handy,and tight Eastern trees.  Also, athletic ability.  A skier who rides his bike 20 hours a week or used to play linebacker in the NFL will have different ways to flex a ski than a desk jockey who is a couch potato on the weekends. 

 

As I have always been 5 foot 9, and through my adult life, never more than 158lbs or less than 150lbs (except when out with a broken leg) it is tough for me to say definitively beyond my own personal experiences.  I do know that when I took up skiing again about 10 years ago after skiing alot as a kid, I could reasonably be classified as an athletic advanced skier, not an expert in any way.  At that point, 170cm-176cm was my go to length. Now that has stretched out to 173-185cm, even though skis have gotten wider as a rule.  My old 170'ish skis weren't much wider than 75-80mm; often narrower. 

 

FWIW, I wear a small in pretty much every brand for ski clothing. For cycling clothing though, always a medium.  I guess there are more "big" skiers than cyclists.

 

So yeah, I think that as a baseline, this probably works pretty well.  Especially when I consider whom I sell skis to, at least 70% of the customers fall in that range. It would be easy to take that a general rule, and then +1/-1 for specific factors that might add up to a longer or shorter size, to at least get a ballpark range. 

post #44 of 53

I put the original data (thanks Alex!) into a statistical model that predicts which one of a set of ordered categories an observation will fall in.  After standardizing height and weight, I found that height and weight were about equally predictive of the size category a skier skied.  Ability wasn't predictive at all.

 

Predicting actual length rather than category, I found that weight appeared to be about twice as predictive (though the confidence intervals still overlapped).  The average person's ski was 180 cm.  For ever standard deviation you were above the mean weight (mean weight was 182 pounds, SD was 27 pounds), you were predicted to ski a 4cm longer ski.  For every standard deviation you were above the mean height (average height was 5'10, SD was 3 in), you were predicted to ski a 2cm longer ski. So for me who is 6'2, 175 I'd be expected to ski a 182 cm ski.  My wife who is 5'3, 110 lb would be expected to ski roughly a 166.  Mine is actually dead on for the average of my 3 skis.  Her prediction is 12cm longer than what she skis. If we had more extremely small people, we might have had a better estimator at that end of the distribution.

 

The reason that the categorical setup is probably more accurate is that what sizes the manufacturers offer control for a lot of variability in ski use/design/ability.  My 186 Billy Goats and 175 Progressor 9+ are very different in size, but fill the same relative spot in the continuum as the manufacturer has already controlled for things such as likely intended use.

post #45 of 53
Thread Starter 

Dawg-  The ability definitely has to figure out in the equation because better skiers amplify their weight by the way they ski.  The counter-argument, which I actually subscribe to, is that these guys may be served better by a stiffer ski in their normal class length (again, that assumes that the manufacturer targets the ski to experts and sizes them accordingly).

 

MB.  your last statement is the main reason for looking into this category-based setup- manufacturers should adjust their sizing for the intended use.   Interesting conclusion about correlation with height/weight, to me it may indicate more that many people have yet to switch to weight-biased sizing.  

post #46 of 53

Very interesting and practical

what I'm looking for now is

Fischer Motive 78 Skis. it goes in four sizes, 154, 161, 168, and 174

according to your chart what size would I get as intermediate, mostly groomed runs ,  5'10, and 170 lb

 

if you some one know fitcher 78 please reply

 

Igor

post #47 of 53
Quote:
Originally Posted by dawgcatching View Post

 

I think that skiing ability would be the next paramater that needs to be analyzed.  Along with that, it would be an terrain situations that would call for a ski out of the "normal" size: big mountain terrain where a 190cm+ comes in handy,and tight Eastern trees.  Also, athletic ability.  A skier who rides his bike 20 hours a week or used to play linebacker in the NFL will have different ways to flex a ski than a desk jockey who is a couch potato on the weekends. 

I pretty much agree with the OP premise and the above.  I am on season 8 or 9 now and remember starting out on 168-170 length skis.  As my skill progressed, I increased the length every few seasons. I am guessing because I am overweight, I like skiing longer skis than my 5'10" height would indicate. The only time I use my 178's??? is when I am skiing hard packed/steep terrain for the first time and feel I need the crutch of an easier to turn ski. On terrain I am familiar with, I just use my 185's.  Hopefully someday, I can just ski the 185's everywhere.

post #48 of 53

I think you make a valuable point--manufacturers offer a range of sizes in each model but the range is different for each model, depending on the construction and use of the ski.  There is no magical formula for length--skiers with more than one ski will usually have different lengths in each ski, but will usually have skis in the same position of the range for each model. Of course this works best for experienced skiers, who know what lengths they like. I would contend that skill and speed are more important than height and weight. Weight should probably matter more for the stiffness of a ski one picks than it usually does. A 250# intermediate probably needs a stiffer ski than a 6 ft 175# advanced skier like me. BTW your chart doesn't work for shirts for me--I wear a large, except in a Wrangler Cowboy Cut which seem to fit really small. 

post #49 of 53

Here is my data point: 

 

Jacket: always a small (sometimes even that is too big in the ever-expanding world of American waistlines. Since when did "small" relate to a 34-inch waist?)

 

Skis: usually middle size, especially if offered in 3 sizes. If offered in 4, either the 2nd shortest (Volkl) or 2nd longest (Head).  If a company is offering a 195cm, I am probably skiing the high 180's size down. If the long length is 185cm for an all-mountain ski, I am probably on the high 170's.  

post #50 of 53
Quote:
Originally Posted by bumpfreaq View Post

Hmmm, I think I need a sweet 21m GS ski in a 42L.


ha!

post #51 of 53
Thread Starter 

Dawg- you are an athlete, so you like your jackets tight and your skis long ;-)

post #52 of 53

So glad I found this. Interesting discussion. I struggled with this a lot. I am relatively new to skiing, but after skiing a lot of rentals I finally ordered my first pair. I'm 5'10", 150-155lbs depending on stress level :) I was confused why the calculators that take weight into account kept putting me in shorter skis than I thought I had needed, and why the folks at the shop also kept sizing me chin-high. I ended up buying Head i.Peak 74 in 163 (comes in 5 sizes and this one is right in the middle). I had actually been thinking about exchanging for the next size up, 170, which would be above my nose tip, just below eyebrows by length sizing. Any thoughts? This chart makes me think that the 163 for a carver ski might be closer to ideal for an intermediate level... I USUALLY get M size jackets, although on occasion I could go for L depending on how loose I need it to be.

post #53 of 53
Quote:
Originally Posted by alexzn View Post

Probably the most often asked gear question here at Epic is "What length of ski Xshould I buy?"   I got somewhat intrigued by the constant repetiotion of the same arguments and I decided to look into the correlation of ski sizes and body parameters.  I also noticed that in the past companies offered skis in 5-6 lengths, nowadays they tend to offer them in three sizes, essentially the equivalent of S,M, L sizing the clothing companies offer. My thought that those sizes roughly correspond to people sizes and the companies themselves adjust the length of those three sizes to compensate for the particular nature of the skis that they make.  Unfortunately, unlike jackets, a misfitting ski is harder to spot, so it helps to look at the numbers.  Thanks to many of you, I got some data points from a brief survey thread, so after an evening of looking up the lengths that those skis come in, I threw them down on a graph (points are slightly dithered to avoid overlap).  Here is what it looks like (trendlines and areas drawn by me by eye):

  

 

 

A few preliminary conclusions:

1. There is a definite trend, and fairly significant clustering.  As Philpug pointed to me, Salomon was onto something when they cam up with their PR sizing in the past.  

2. The weight is a more important factor than height, so that should be a primary parameter for choosing the ski size.

3. There is a fair deal of confusion on the boundary between sizes L and M- seems that some people are too timid to buy into the larger size that their body type demands even though they fall very close to the trendline (surprisingly, there is no clear correlation with ability, at least as stated in the surveys), and some people listen to their ego more than to their body measurements.    There is also evidence that older sizing by height is still prevalent (notice that all the red symbols that are spilled over to the MED size area are above the trend line.  The two red dots near the SM  area belong to someone who looks like a young racer, so he is definitely an outlier.   

4.Indeed the ski size roughly correlates with the size of your ski jacket (Euro fit:-).  

5. I would strongly support sizing based on this type of analysis. In fact, if your demo suggests that you need to buy a ski in a size that does not fit this chart, then you are probably looking for a wrong ski for your level of skiing/fitness.  In other words, if you feel like you can only handle a ski that is a size down from what the chart suggests, then you are not strong enough for that ski and you may look into something softer and more forgiving.  If you belong to the M group and feel like the M size ski is too floppy, you need to get a more aggressive/stiffer model rather than a longer ski.   

6. I'd say it again, the defining parameter should be your weight, not your height. 

 

Now, flame away :-)

This is fun, not flames. Would suggest the relationship appears to be curvilinear based on your highly random sample. Meaning it bends down as it approaches the right top corner. That would reflect the fact that weight increases and increases and...while height tends to give out rapidly. Also, what you're regressing here ultimately can be distilled to something like CDC's Wt/Ht or the common Body Mass Index (BMI), or Wt/Ht2. It's decently associated with %body fat for whole populations, but suffers from the same problems as any other index or regression using weight; it doesn't reveal composition. So you can be quite heavy but fairly lean. (Think athletes in general, NFL types in specific. Or vice versa, a teddy bear.) Jacket size will on average pull in some variation from skeletal breadth and density, some from muscle mass, and some from how much of a roll you have around the middle. So I could wear a medium because I am a swimmer and have broad shoulders, or because I am a teddy bear? Put another way, is weight from muscle the same as weight from fat?

 

Hmmm. So how does that work for skis? Does the Teddy Bear use the same length as the College Swimmer? You could say yes, mass is mass. Or you could say no, Dawgcatching can bend a ski more than almost anyone here, and likes to go longish, cuz he's a competitive mountain biker, yet he's a small to mejum jacket I'd bet. Also speed, since my ability to bend a ski is not a function just of my mass but of the force I put to the ski. Yeah that tired old F=Ma. Some of us ski faster than others. Or contract harder at the knee. Or want more stability than maneuverability. Agree with Ghost about the zero sum game of leverage and height, but where did acceleration wander off to? Or terrain? Also construction, since my old Pocket Rockets definitely had a different cross sectional construction, but a fairly similar cross sectional area, to my Stormrider 95's, and as I recall a different flex.

 

Further using moi as an example, wear a medium, my weight fits in your medium box, but ski on everything from 165 cm to 188 cm, depending on what the ski's being used for and how it's made. In some cases that's the upper increment, in some cases the lower, in some the middle. Don't have a comfort zone. Or place where I'm feeling like the ski is too much or too little, as long as I'm using it for the mission intended. th_dunno-1[1].gif

 

Anyway, almost no one on this thread is probably typical. And not the intended target of the graph. Which is cool. Appreciate the work you put into it. Food for thought, since we all sense that many recreational skiers are on the wrong ski. A way to approach it. Kudos.  


Edited by beyond - 1/23/13 at 5:17pm
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