EpicSki › The Barking Bear Forums › On the Snow (Skiing Forums) › Ski Gear Discussion › Ski choice & skier weight?
New Posts  All Forums:Forum Nav:

Ski choice & skier weight?

post #1 of 24
Thread Starter 
Two skiers - identical in terms of technical skill and aggressiveness.

One weighs 200 pounds, the other 135. How much does this affect ski choice?

If I look at the Elan Magfire line - assuming both are expert level skiers, does the 200 pounder need the Mag 12, while the 135 pound skier could use the Magfire 10? Will they both get the same performance from the ski? Would the extra layer of Ti in the Magfire 12 be too much for the 135 pound skier but just right for the 200 pound person? It stands to reason the 135 pound skier just cannot generate the same force as his heavier counterpart and would need a softer ski despite his technical ability. But I've never gotten a clear answer on this. Would appreciate everyone's thoughts.
post #2 of 24
The 200 lb skier would probably need a longer length. The 135 lb skier probably skis fast enough to use the 12, but doesn't need as long a length. It is after all, inspite of all the marketing hype aimed at flattering the customer, a short recreational shaped ski, not a 240cm DH board.

It does depend on how he skis though, if he wants something that performs well at slower speeds on softer snow the yshould probably go with the 10.
post #3 of 24
Yep, length. Treat the person's weight similar to height. Tall and/or heavy people need longer skis in a particular model. Short/light people go with the shorter skis. It's actually analogous to binding settings to some extent -- you'd want to consider the moment (lever arm) of the person's weight and height over the ski along with their skier level. The higher the moment and skier level, the longer the ski needed for stability and control.
post #4 of 24
Quote:
Originally Posted by yelloboy View Post
Two skiers - identical in terms of technical skill and aggressiveness.

One weighs 200 pounds, the other 135. How much does this affect ski choice?

If I look at the Elan Magfire line - assuming both are expert level skiers, does the 200 pounder need the Mag 12, while the 135 pound skier could use the Magfire 10? Will they both get the same performance from the ski? Would the extra layer of Ti in the Magfire 12 be too much for the 135 pound skier but just right for the 200 pound person? It stands to reason the 135 pound skier just cannot generate the same force as his heavier counterpart and would need a softer ski despite his technical ability. But I've never gotten a clear answer on this. Would appreciate everyone's thoughts.
I would say that a 200 Lbs skier would reduce the Mag 12 to the performance level of a Mag 10; while a 135 lb skier would experience Mag 12 level performance from a Mag 10.

Cheers,

Michael
post #5 of 24
Thread Starter 
Quote:
Originally Posted by barrettscv View Post
I would say that a 200 Lbs skier would reduce the Mag 12 to the performance level of a Mag 10; while a 135 lb skier would experience Mag 12 level performance from a Mag 10.

Cheers,

Michael
Thanks everyone, that was pretty straightforward - with most saying that it is a length issue and one saying that stiffness of ski will also play a role.

Anyhow, I'd be open to recommendations for me (I am the 135lb skier) as I'm trying to choose between the Magfire 12 and 10, in a 168 or 160. I'm 5 foot 7, 135, pretty agressive and a decent skier. I've never really bothered to look closely at the different level systems but I'd say pretty confidently I'm at least a 7.

Do I go with the Magfire 12 in a 160? Or the Magfire 10 in a 168? Or Magfire 10 in a 160?

As an aside, I have the S12 in a 168 (2 Ti sheets like the Mag 12) and that ski is quite fun and fast on the groomers, great through a nastar course, but a load for me anywhere else. Looking for something more versatile, hence the interest in the Magfire line.

Thanks for the input!!
post #6 of 24
The S12 is one of the stiffest skis around. If you can handle this ski, you can probably ski the the Mag 12 easily. The Mag 10 is a low speed version of the Mag 12. It has a much greater sidecut which improves turn-in. Extreme sidecut skis like the Mag 10 are not stable at higher speeds or longer turns, however.

If you are looking for a soft snow alternative to complement the S12 look to the Dynastar Legend 8000, Head Monster i.M 82 and the Fischer AMC 79.

If you want something to directly replace the S12, consider the Fischer RX8 or Head Supershape.

Cheers,

Michael
post #7 of 24
It's already been kind of pointed out, but the Mag 10 is NOT a lesser version of the Mag 12. They're really two totally different skis and Elan's marketing department really screwed up on this one (everyone assumes that the 10 is "less" than the 12, but it's an apples-to-oranges comparison).

You and I both have the S12 in the same length. I'm 5' 7" 175lbs and I need SPEED to be able to put a good bend on the S12 (it's the stiffest ski I own). The Mag 12 or 10 aren't anything like the S12.

What are you really looking for? Are you trying to go wider? Where will you be using the ski? What are your body measurements? What's your skill level?

Also note, metal layers in most skis do not add stiffness - they add dampness (an exception that comes to mind are Volants). Most titanal layers are flexible - it's the wood and fiberglass components that make up the stiffness (thanks EpicSki - I learned something ).

As far as replacing the S12 - I strongly recommend the SpeedWave series - either the 12 or the 14.
post #8 of 24
As Noodler said it depends on the line. Some lines of skies have basically the same ski in different stiffness. It's rarely apples to apples unless you are comparing different lengths of the same model.

First choose a ski appropriate to you ability and use and THEN choose the length in that model. If you try to do both at the same time you will drive yourself nuts, like many of the gearheads here ;-)
post #9 of 24
Quote:
Originally Posted by Noodler View Post
Also note, metal layers in most skis do not add stiffness - they add dampness (an exception that comes to mind are Volants). Most titanal layers are flexible - it's the wood and fiberglass components that make up the stiffness (thanks EpicSki - I learned something ).
I wouldn't say Volants are a special exception -- on any ski with a metal layer a good distance outside the core, the metal is going to be carrying a "not-insignificant" chunk of the load. Of the 2 skis I own that have metal layers, the layers are on the outside of the core. Generally one layer just under the topsheet on top and/or one layer just above the P-TEX on the bottom, if you believe cartoons on the ski manufacturer's website.

I just did a quickie estimate of the load carrying of the layers and the core (independent of the materials) and the layers could be carrying anywhere from 10% to 40% of the load depending on thickness and how far from the center of the ski they are (the farther they are the more effect on stiffness). So I learned something too! Yeah they are floppy pieces of sheet metal, but glued into the structure far from the bending center, they can have a big effect. They can take on an i-beam effect in extreme cases (Volant).
post #10 of 24
skier219 - I forget who posted the info, but what they said was that the titanal layers we're finding in skis these days are not stiff on their own. They're down right floppy and many are not a "full" sheet (there's holes punched out of them to reduce weight). This poster seemed to really have an understanding of ski construction and made a strong point that the metal layers are not adding stiffness (or "load carrying" as you say) - they're just adding dampness. Maybe this info is wrong, but it sure sounds plausible to me.

I believe that Volants are an exception because the steel topsheet is stainless and built as a cap to create much of the torsional rigidity and stiffness in those skis.
post #11 of 24
Quote:
Originally Posted by barrettscv View Post
The S12 is one of the stiffest skis around. If you can handle this ski, you can probably ski the the Mag 12 easily. The Mag 10 is a low speed version of the Mag 12. It has a much greater sidecut which improves turn-in. Extreme sidecut skis like the Mag 10 are not stable at higher speeds or longer turns, however.

If you are looking for a soft snow alternative to complement the S12 look to the Dynastar Legend 8000, Head Monster i.M 82 and the Fischer AMC 79.

If you want something to directly replace the S12, consider the Fischer RX8 or Head Supershape.

Cheers,

Michael
I agree with this advice.
post #12 of 24
Quote:
Originally Posted by Noodler View Post
skier219 - I forget who posted the info, but what they said was that the titanal layers we're finding in skis these days are not stiff on their own. They're down right floppy and many are not a "full" sheet (there's holes punched out of them to reduce weight). This poster seemed to really have an understanding of ski construction and made a strong point that the metal layers are not adding stiffness (or "load carrying" as you say) - they're just adding dampness. Maybe this info is wrong, but it sure sounds plausible to me.

Almost none of the ski materials are stiff on their own -- it's only when bonded into the structure that the whole unit becomes stiff. Same goes for any composite structure in general. The metal sheets are indeed floppy all by themselves, but when glued into the structure they have the potential to add a lot of strength if placed strategically. What you are doing is essentially using the metal layers as cables and braces, which resist tension and compression when the ski is bent.

As you can read here:

http://en.wikipedia.org/wiki/Bending

the material on the outer edges of a beam carries a majority of the load, as the stresses are greatest there. So if you can use a stronger (in tension and compression) material on the outer edge, you can get an overall stronger structure. Thus, having outer metal skins serves a double purpose; the extra material increases the thickness of the structure (akin to making the core taller), but being metal which is significantly stronger than wood in tension and compression, you can handle higher loads where it matters the most. As long as the glue between the wood core and outer metal layers holds everything together, the metal layers can really beef up the stiffness. If you have ever seen a honeycomb/skin structure, with metal skins bonded over a fiberglass core, it's the same deal. Many airplane parts are made this way and are quite strong. Even the cheapo luan interior doors used in modern houses are fairly stiff, and they are just 1/8" wood panel glued over cardboard honeycomb -- all floppy parts, but when glued up the outer skins make for a stiff overall structure.

Does this make sense? I am not sure what the other guy was referring to, but you can't consider the metal skins by themselves to know how they behave when bonded into the composite structure. Even if they are floppy as heck, they would be very strong in tension (try to pull one and I bet it won't stretch much or at all). It's this property that makes them really beef up the ski's stiffness when used as an outer layer. The only time a layer would contribute nothing to stiffness is if it was mounted in the center of the ski where the bending stresses are zero (refer to article above).

By the way, if you have ever seen a foam core ski, you might notice that the core material is pretty much just a filler. The sidewalls and skins of foam core skis take all the load, with much of it in the skins. The foam core itself is pretty much just a medium to glue everything together!
post #13 of 24
I dug up some more info about composite ski construction:

"There are an infinite number of laminate types that can be developed. These materials can be categorized into three basic areas: core materials, high strength and high stiffness skins, and outer protective layers. Core materials typically serve the function of connecting and spacing the skins to develop stiffness and strength in a sandwich arrangement. The key property of core materials is shear strength, to insure shear conductivity between the skins and the ability to sustain loads and bending. Core materials are normally wood, honeycomb, and structural foams. The outer structural layer or skins traditionally are either metal or composite, either in combination with a core material or a layup of high strength and stiffness layers. Composite materials offer the widest range of high strength skins with the ability to change fiber type (fiberglass, carbon, and aramid) in addition to the fiber volume and orientation. Composites are well suited for large deflection applications where high strain capability and fatigue is required."

This sort of highlights the purpose of the core in a sandwich construction, which is to tie the skins together so that they form a strong combined structure. The cores need to be strong in shear. As I alluded to before, the skins would be there to fight tension and compression and need to be strong under those loads.

Here's a sketch of a beam (ie, a ski in our application) with some sort of bending moment applied:



The top sketch shows a single material, let's say the ski core. When bent, the bottom is in tension (stretched) and the top is in compression (squashed).

The bottom sketch just shows the effect of adding skin layers (for instance metal). As applied, these layers would be resisting the outer tension and compression on the structure. To add stiffness to the overall structure, the layers don't have to be very stiff by themselves, but they need to have high resistance to tension and compression. When glued onto the core, this will have the effect of stiffening up the structure.
post #14 of 24
Quote:
Originally Posted by Noodler View Post
skier219 - I forget who posted the info, but what they said was that the titanal layers we're finding in skis these days are not stiff on their own. They're down right floppy and many are not a "full" sheet (there's holes punched out of them to reduce weight).
I thought the holes helped them alter the flex point/pattern of a ski versus just reduce weight.
post #15 of 24
Quote:
Originally Posted by lowphat View Post
I thought the holes helped them alter the flex point/pattern of a ski versus just reduce weight.
'tis true, they do. Stress versus strain is a linear relationship (slope is Young's Modulus of elasticity), i.e. the more you stretch (or compress) the metals "skins" the bigger the stress. Stress times cross-sectional area of the metal skin is the force they can apply. Force times distance away from the neutral axis (think middle here) is the bending moment or torque they can apply to resist the ski bending or flexing. More metal = less bending. Less metal = more bending.
Main point still holds - Metal glued to the ski stiffens it up, a lot.

I haven't been on the magfires, though I have tried the S12. I'm guessing that the 12 will limit your ability to enjoy the skis at slow speeds, especially in softer snow. The 10 will make going fast a pita. If you're not happy with the S12's performance in bumps and softer snow, you won't like the Mag12 either, but I wouldn't want the 10 for going fast. RX8 is a nice compromise, but it doesn't have that smooth damp feel of the Elans. If you want a similar feel, try Dynastar, atomic or Nordica. Dynastar has a smooth feel, but a little livlier. Atomic is a little solider. Nordica?
post #16 of 24
Thread Starter 
Quote:
Originally Posted by Ghost View Post
'tis true, they do. Stress versus strain is a linear relationship (slope is Young's Modulus of elasticity), i.e. the more you stretch (or compress) the metals "skins" the bigger the stress. Stress times cross-sectional area of the metal skin is the force they can apply. Force times distance away from the neutral axis (think middle here) is the bending moment or torque they can apply to resist the ski bending or flexing. More metal = less bending. Less metal = more bending.
Main point still holds - Metal glued to the ski stiffens it up, a lot.

I haven't been on the magfires, though I have tried the S12. I'm guessing that the 12 will limit your ability to enjoy the skis at slow speeds, especially in softer snow. The 10 will make going fast a pita. If you're not happy with the S12's performance in bumps and softer snow, you won't like the Mag12 either, but I wouldn't want the 10 for going fast. RX8 is a nice compromise, but it doesn't have that smooth damp feel of the Elans. If you want a similar feel, try Dynastar, atomic or Nordica. Dynastar has a smooth feel, but a little livlier. Atomic is a little solider. Nordica?
Ghost - That's right, the S12 is awesome when I am flying, and progressively less awesome the slower I go or as conditions vary away from hard pack or groomed. Bumps, crud, at moderate speeds and the ski is a load for me.

So the Mag 10 is clearly not a 'go-fast' ski, understood - but how about it's performance in bumps and crud? Anyone w/ experiences?

Other good recs for bump skis that will be okay at speed on hard pack? OR is that asking too much? RX8?
post #17 of 24
Quote:
Originally Posted by yelloboy View Post
RX8?
Yes, the RX8 should be considered. YB, at your weight, the RX8 can do it all in a 160cm size.

Michael
post #18 of 24
I feel the need to weigh in on this one

I also am a 135 lb skier. I have demoed a lot of skis over the years that got rave reviews that just didn't suit me. While reading the reviews, lo and behold, the testers weigh in at a healthy 200lbs. Even adjusting length, a Nobis anything just ain't gonna be the ski for me. When I hear some halfback kinda guy complaining that a ski is too soft my ears perk up and i get interested. I seem to have majored in Dynastar over the years with a minor in Fischer. They just seem to work for my weight/technique.

edit to add the RX8's in a 165 are in my quiver
post #19 of 24
Thread Starter 
Quote:
Originally Posted by stoweguy View Post
I feel the need to weigh in on this one

I also am a 135 lb skier. I have demoed a lot of skis over the years that got rave reviews that just didn't suit me. While reading the reviews, lo and behold, the testers weigh in at a healthy 200lbs. Even adjusting length, a Nobis anything just ain't gonna be the ski for me. When I hear some halfback kinda guy complaining that a ski is too soft my ears perk up and i get interested. I seem to have majored in Dynastar over the years with a minor in Fischer. They just seem to work for my weight/technique.

edit to add the RX8's in a 165 are in my quiver
How have the RX8s treated you in the bumps? From what I've read, they seem fantastic on groomers or hardpack, but haven't seen as much about their performance on bumps and crud...

edited to add - My concern is that the RX8 would just be a replacement for the S12? Granted going down 8cm in length will make a difference in the bumps, but is that enough?
post #20 of 24
I'm about your weight (135lbs) and ht (5'6")... I have the 666's in a 168(thanks Sac!), which are almost the same ski as the Mag12's. They are easy skiing with a big sweet spot. You can push them or just relax & let them do the work for you. If anything, I prefer something with a stiffer shovel for the chop. You'll have no problem handling them..
post #21 of 24
Quote:
Originally Posted by yelloboy View Post
How have the RX8s treated you in the bumps? From what I've read, they seem fantastic on groomers or hardpack, but haven't seen as much about their performance on bumps and crud...

edited to add - My concern is that the RX8 would just be a replacement for the S12? Granted going down 8cm in length will make a difference in the bumps, but is that enough?

I got them at the end of last season. The bumps at that point were non- existent. They do hook up and go on the groomers though.
post #22 of 24
Quote:
Originally Posted by yelloboy View Post
How have the RX8s treated you in the bumps? From what I've read, they seem fantastic on groomers or hardpack, but haven't seen as much about their performance on bumps and crud...

edited to add - My concern is that the RX8 would just be a replacement for the S12? Granted going down 8cm in length will make a difference in the bumps, but is that enough?
Others have said the RX-8 were decent in bumps in crud, but my experience is that there are other skis that are much better at both. I have pretty much relegated the RX-8 to the role of a hardpack carver in my quiver. For bumps or crud, I would pick my Elan M666 over the RX-8 by a long shot.
post #23 of 24
About 16 years ago, Salomon broke convention and introduced a length system based not on the skiers height but solely on the skiers weight. It was called the PR system and these skis didn't even have their length in centimeters written anywhere on the topsheet.

Based on my weight, I ended up buying their PR7 size ski for special slalom racing (Equipe 10 - 3V model). They turned out to be 198 cm.

I was please with these skis but always felt I got railroaded into buying too long a pair by sticking to their formula.

Six years after this purchase, on a demo day at La Plagne, I tried a pair of much shorter PR4 Salomon slalom skis, which I found much easier to turn in the gates.

I know that any ski can only feel the weight and strength of the skier who rides it, and the ski has no idea if the skier is tall or short. So in my opinion, and perhaps Salomons as well, height should not be a factor in ski selection, only the skier's weight and strength and the speed at which he/she wants to go.

But from my personal experience, I found the shorter Salomon skis easier to turn but less stable at higher speeds, even though, in theory, this shorter Salomon ski was never intended for a skier of my weight.

Salomon abandoned their PR system with their model year 1999-2000. R.I.P.
post #24 of 24

Ski flex and rigidity

Has anyone found a web site which lists
a skis longitudinal flex and tortional
rigidity in tabular format?

The University of Utah used to do
this years ago.

Thx,
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Ski Gear Discussion
EpicSki › The Barking Bear Forums › On the Snow (Skiing Forums) › Ski Gear Discussion › Ski choice & skier weight?