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Point Of Diminishing Returns With Regards To Ski Length - Page 2

post #31 of 153

One factor I haven't noticed in this discussion is the condition of the course. If the entire course were water injected such that it would support your weight without a shorter ski digging in excessively anymore than the longer ski and thus slowing you down I can't see why a very short pair of skis wouldn't be superior provided you can maintain good fore aft balance. I have a pair of 165cm race stock Elan SLX that I like very much and I have found myself suddenly behind the skis on several occasions. It really takes quite a bit of skill to stay centered on them. Unlike the older "straight" slalom skis of an earlier era you cannot get momentarily back on the skis and depend upon them to support you while you play catch up to regain balance. I mean if you aren't sinking into the snow and the amount of edge you have available is sufficient to hold an arc then you might think a pair of ice skates would be ideal. I'm being a bit facetious here because even water injected courses aren't usually hard enough to keep an ice skate from sinking in but I imaging you can see my point. The biggest drawback to a shorter pair of skis that I can think of is the amount of skill required to keep you perfectly balanced over them at all times on a course. Since the acceleration of the skis varies considerably depending upon changes in slope, snow surface, radius of the turn and position in the turn you must anticipate all those factors in order to have your body in just the right place at all times. Longer skis provide for a greater margin for error.

 

This is all based upon the assumption the skis shape ie turn radius is appropriate to the course. In the old days ski shape in a turn was much more a function of the flex of the ski and the skier's ability to shape the ski accordingly. Thus a 200 or 205cm slalom ski was pretty much the norm. That was before the advent of water injection allowed for shorter skis. Even the longer skis would produce fearsome ruts for those out of the first seed in the softer snow conditions.

post #32 of 153
Thread Starter 

Couple things:

 

First - BWPA,

 

I want to make sure that you understand I'm not arguing with anything you said.  Your are correct.  It's just that in my pursuit of this knowledge, I'm trying to keep it very specific at first.  I understand the need for different skis for different things and even having the same ski in different lengths/TR/stiffness, so you can have a well rounded quiver.  If you have 8 pairs of skis that cover a range and probably have some over lap, then notice you have a gap in one particular area, how do you make sure you get the exact ski (length/stiffness/tr) you need.

 

Second,

As some of you know, or have come to realize from reading my posts, though I have an instructor badge, I haven't been skiing that long so I don't have the depth of experience that many of you have.  I'm 51 and started skiing at 46.  Bought my first shaped skis at 48, I took my first lesson at 49.  I did ski a few times in high school but never had a lesson and I don't think I went more than 6 or 8 times.  And it was the '70's and I was young so better than half the time my mind was being enhanced on the chair lift wink.gif .  And it was over 30 years ago.  Since I don't have a full life of skiing to draw from, I'm trying to follow the old proverb of "A wise man learns from his mistakes.  An even wiser one learns from someone else's."

 

So when I ask people for recommendations about getting another ski and tell them what I'm looking for, I get comments that are all over the map - "Don't get a race stock SL ski.  Too much work and not much fun."  "Get something around 16/17 turn radius."  "Get a cheater GS  race ski around 170 or 175."  "Get a cheater SL race ski."  and of course  "Go long."  etc.  All ending with, "You'll love it."  or something to that effect.  These aren't from salesman but ski instructor/race buddies that all know me and ski with me.

 

I have a race stock Elan SLX 155 - love it but I know I need something longer; stability isn't the issue; it's slower than I want it to be.

I have a race stock Elan GSX 176 - love it but I know it is too much work (21.2 M TR) for me outside of the race course.

 

I've been trying to apply math and science to find the happy medium between the two, which got me thinking of a 165 SL either race stock or cheater race.  But I keep getting hung up on (because the 155 seems to dig in too much) do I need longer than 165?  Then it's will a race stock 165 be as much work as the race stock gs?  If I get a sl cheater in 170, will that fit the bill even though the TR is smaller than a cheater gs in the same size.

 

Yes I think about things too much and obsess about things.  That's me.

 

So the chance of me being able to spend a few weekends demoing skis and then being able to pick a ski are fairly slim; mainly based on my schedule and work load.  The chances of me being able to get in the ball park and probably in the correct area from study and research are much higher - hence this thread.

 

What I've learned is TR and Stiffness are really what my focus should be since for "my" purposes length isn't that big of a player.  Consider that SL race and SL cheater are very close in length and TR but vary more in stiffness.  Same with GS race and cheater GS.

 

Again, appreciate your patience,

 

Ken

 

 

 

 

 

post #33 of 153

Well you can get custom skis...

 

IMO, the better I get, the less skis seem to matter. 4 years ago when I moved out to UT, I would flail in powder on 85mm all mountain skis and would use 108  scott P4s to make it easier. Now I can ski it on 85mm all mountain skis -- no problem. You said you have only been skiing for a few years. Maybe those chainsaws you are juggling will feel more like eggs in a couple years.


Edited by tromano - 7/15/11 at 6:52am
post #34 of 153
Thread Starter 
Quote:
Originally Posted by tromano View Post

Well you can get custom skis...

 

 

No I can't.  Can't figure out what the specs are to give them frown.gif

 

 

You said you have only been skiing for a few years. Maybe those chainsaws you are juggling will feel more like eggs in a couple years.



 I sure do hope so.  My friend, who is slightly shorter than I but the same weight, skis 183 race stock fischers gs as his all mountain skis eek.gif  He's also been skiing 50 years.

 

post #35 of 153

A couple of points that are clear to me from my experience.

 

There is no way any SL ski will perform well as a GS ski.  There is no way any GS ski will perform well as a SL ski. You need both, and will have to live with the lack of performance when the ski is pressed into duty in the wrong category.

 

Length for SL should be around 165 cm.  GS should be 185 to 190.

 

Between full-on, full metal jacket, here's the beef, race ski and one step down, you have to decide if you want a ski that only feels good when you are blasting at speed, or if you want it to feel good all the time.  The difference in performance will not be that much when you're not pushing the envelope.   I  find I feel a little unsafe at speed and that I have to be a little bit more careful when blasting on softer skis than when on robust skis, but the softer skis would be my choice when I need to go slow on moderately steep runs with deeper heavy cut up crud; the really beefy skis are dysfunctional at slow speeds.

 

post #36 of 153
Quote:
Originally Posted by Ghost View Post
 GS should be 185 to 190.

 



That is true if you are big enough and running a real GS, but here in the states we have this funky thing called NASTAR (which I believe OP was asking about) which runs 18-to-20 meter gates... sometimes the turning radii and lengths normally associated with the longer radius turns of real GS courses (and those being on usually steeper and longer courses) will be too much in NASTAR for all but essentially-pro racers.  I would only agree that a 185 is appropriate in NASTAR if the skier in question is very tall, very large, and/or very (VERY) good.

 

OP said he was 5'7' and light... not sure he's going to have an easy time bending a 185 GS through NASTAR, especially if he already feels like they are "chansaws" (and I'd think anyone comfortable at speed would feel the opposite way... i.e. being on softer skis at speed is bad (and I believe you said that above Ghost))

post #37 of 153


"Digging In" (Not really a technical ski term) is not the problem with a slalom ski in GS. It is the shape of the ski when compared to the distance between the gates.

 

Injected or not. A smaller raidus ski with less taper angle in the tail provides more across the hill turn finish then a bigger radius more taper angle GS ski.

 

It's very simple. You are skiing farther then the skier on a straighter skis that allows more turn finish down the hill then across it.

 

More taper angle in the tail allows early and straighter release of the turn without skidding. In order to ski a straighter line wiht a small radius slalom ski some where you must get off of the edge before the tail takes you too far across the hill.

 

Carving is always faster the skidding, if you can stay in the course that is!
 

Quote:
Originally Posted by oisin View Post

One factor I haven't noticed in this discussion is the condition of the course. If the entire course were water injected such that it would support your weight without a shorter ski digging in excessively anymore than the longer ski and thus slowing you down I can't see why a very short pair of skis wouldn't be superior provided you can maintain good fore aft balance. I have a pair of 165cm race stock Elan SLX that I like very much and I have found myself suddenly behind the skis on several occasions. It really takes quite a bit of skill to stay centered on them. Unlike the older "straight" slalom skis of an earlier era you cannot get momentarily back on the skis and depend upon them to support you while you play catch up to regain balance. I mean if you aren't sinking into the snow and the amount of edge you have available is sufficient to hold an arc then you might think a pair of ice skates would be ideal. I'm being a bit facetious here because even water injected courses aren't usually hard enough to keep an ice skate from sinking in but I imaging you can see my point. The biggest drawback to a shorter pair of skis that I can think of is the amount of skill required to keep you perfectly balanced over them at all times on a course. Since the acceleration of the skis varies considerably depending upon changes in slope, snow surface, radius of the turn and position in the turn you must anticipate all those factors in order to have your body in just the right place at all times. Longer skis provide for a greater margin for error.

 

This is all based upon the assumption the skis shape ie turn radius is appropriate to the course. In the old days ski shape in a turn was much more a function of the flex of the ski and the skier's ability to shape the ski accordingly. Thus a 200 or 205cm slalom ski was pretty much the norm. That was before the advent of water injection allowed for shorter skis. Even the longer skis would produce fearsome ruts for those out of the first seed in the softer snow conditions.



 

post #38 of 153
Quote:

Originally Posted by L&AirC View Post

 

I have a race stock Elan SLX 155 - love it but I know I need something longer; stability isn't the issue; it's slower than I want it to be.

I have a race stock Elan GSX 176 - love it but I know it is too much work (21.2 M TR) for me outside of the race course.

 

I've been trying to apply math and science to find the happy medium between the two, which got me thinking of a 165 SL either race stock or cheater race.  But I keep getting hung up on (because the 155 seems to dig in too much) do I need longer than 165?  Then it's will a race stock 165 be as much work as the race stock gs?  If I get a sl cheater in 170, will that fit the bill even though the TR is smaller than a cheater gs in the same size.

 

I'm your size and was all set to join the crew of folks recommending an 18-19m ski in 175-180cm, but if the SLX is stable enough for you and the GLX is too much work, you might be happier for now with a 165cm race-stock slalom ski.  A 165cm ski with a 12-13m radius instead of the 11ish of your SLX will make bigger turns due to the radius and almost certainly stiffer construction, so it might fit the bill for you.

 

I think you'll eventually want something in the 18-19m range and 175-180cm, but if your GLX is too much work with a 21m radius, I'm not sure that would be enough of a step down to put you into the comfort zone you seem to be looking for right now.  A possible exception is the Atomic d2 ski in that category.  The d2 skis are supposed to be really easy to initiate, so it might be the best of both worlds for you right now.

 

A race-stock slalom ski is not nearly as much work as a race-stock GS ski.

 

It seems like you've got your choices narrowed down to 2-3 options by now, which should be a demo-able number.  Happy hunting. :)

post #39 of 153
Quote:
Originally Posted by Atomicman View Post


"Digging In" (Not really a technical ski term) is not the problem with a slalom ski in GS. It is the shape of the ski when compared to the distance between the gates.

 

Injected or not. 


Hence my comment:"This is all based upon the assumption the skis shape ie turn radius is appropriate to the course." (contained within my comments that you quoted). If the radius of the ski were the only issue I don't think the original poster would have much difficulty answering his original question. It would simply be a matter of matching the designed turn radius of the ski to the radius of the turns most commonly set in the courses he races on. Of course we know there is more to this as well including the bend imparted to the ski by flexing which alters the turn radius as well. We also know that there are a variety of turn shapes. Not all or even most turns are an even curve of constant radius.  My point was that, everything else being within acceptable range, the things (other than FIS regs) that limit how short a ski might work are ability to maintain balance and the ability of the snow to support the ski.  As the snow becomes softer and the ski shorter a point is surely reached when the shorter ski is slower simply because of the depth of the groove it will carve in the snow. This is what I meant by "digging in", which is not as you point out, exactly a technical term. While a shorter ski might, with the appropriate designed radius, and a skillful athlete be capable of carving a clean arc in a gs radius turn, there could be a considerable amount of drag if the snow is not rock hard and so the ski is "digging in".

 

There's another issue related to ski length that I alluded to when i mentioned bending.  I used to race on 193 to 205 cm slalom skis that were relatively straight and yet they could be used to carve a turn because they could be bent in an arc. I think this is part of the issue with skis which are longer. Longer skis, to a point, can be more versatile if they can be bent to a variety of turn arcs. This is one of the great changes in ski design today that gets very little press. In years past skis often were quite stiff in order to produce edgehold. Today's skis are relatively soft flexing, lengthwise compared to older race skis. Damping technology has proven able to reduce edge chatter and maintain edgehold as well or better than stiffness, hence a relatively shorter  ski can be soft enough to be amenable to being bent to shape the turn. This is part of the reason why a 185cm gs ski is common where a 210 or 215cm gs ski was once standard.

 

Fwiw I have a pair of race stock 165 cm Elan SLX which are great for free skiing (on hard snow). The one thing they do not do very well is skid.

 

post #40 of 153


If you read my post much earlier I alrerady covered all that. Slsom skis don't "Dig In" anymore then a GS ski unless you cause either to do so!

 

Also chatter is caused by pilot error. Poor technique Worng pressure in the wrong place in the turn,  in the wrong manner on the ski at the wrong time.

 

I ski some of the dampest skis around and on hard snow, with a lot of pitch, it takes very advanced technique to avoid chattering.

 

I also believe you are underestimating theeffect of tail geometry of a SL ski comapred to a GS ski.
 

Quote:
Originally Posted by oisin View Post




Hence my comment:"This is all based upon the assumption the skis shape ie turn radius is appropriate to the course." (contained within my comments that you quoted). If the radius of the ski were the only issue I don't think the original poster would have much difficulty answering his original question. It would simply be a matter of matching the designed turn radius of the ski to the radius of the turns most commonly set in the courses he races on. Of course we know there is more to this as well including the bend imparted to the ski by flexing which alters the turn radius as well. We also know that there are a variety of turn shapes. Not all or even most turns are an even curve of constant radius.  My point was that, everything else being within acceptable range, the things (other than FIS regs) that limit how short a ski might work are ability to maintain balance and the ability of the snow to support the ski.  As the snow becomes softer and the ski shorter a point is surely reached when the shorter ski is slower simply because of the depth of the groove it will carve in the snow. This is what I meant by "digging in", which is not as you point out, exactly a technical term. While a shorter ski might, with the appropriate designed radius, and a skillful athlete be capable of carving a clean arc in a gs radius turn, there could be a considerable amount of drag if the snow is not rock hard and so the ski is "digging in".

 

There's another issue related to ski length that I alluded to when i mentioned bending.  I used to race on 193 to 205 cm slalom skis that were relatively straight and yet they could be used to carve a turn because they could be bent in an arc. I think this is part of the issue with skis which are longer. Longer skis, to a point, can be more versatile if they can be bent to a variety of turn arcs. This is one of the great changes in ski design today that gets very little press. In years past skis often were quite stiff in order to produce edgehold. Today's skis are relatively soft flexing, lengthwise compared to older race skis. Damping technology has proven able to reduce edge chatter and maintain edgehold as well or better than stiffness, hence a relatively shorter  ski can be soft enough to be amenable to being bent to shape the turn. This is part of the reason why a 185cm gs ski is common where a 210 or 215cm gs ski was once standard.

 

Fwiw I have a pair of race stock 165 cm Elan SLX which are great for free skiing (on hard snow). The one thing they do not do very well is skid.

 



 


Edited by Atomicman - 7/16/11 at 9:35am
post #41 of 153
Quote:
Originally Posted by BlueSquare View Post





That is true if you are big enough and running a real GS, but here in the states we have this funky thing called NASTAR (which I believe OP was asking about) which runs 18-to-20 meter gates... sometimes the turning radii and lengths normally associated with the longer radius turns of real GS courses (and those being on usually steeper and longer courses) will be too much in NASTAR for all but essentially-pro racers.  I would only agree that a 185 is appropriate in NASTAR if the skier in question is very tall, very large, and/or very (VERY) good.

 

OP said he was 5'7' and light... not sure he's going to have an easy time bending a 185 GS through NASTAR, especially if he already feels like they are "chansaws" (and I'd think anyone comfortable at speed would feel the opposite way... i.e. being on softer skis at speed is bad (and I believe you said that above Ghost))


What you say is very true; if he wants a ski to excel in a course that is half way between SL and GS then he should get a ski that is between the two, like the old Dynastar SX11 or Fischer WC RC Pro.  Both would work well there.  For free skiing with this ski he would give up a little on the top end (long turns at high speed) and a little at the low end (short turns).  There is still compromise, but it's a little from both ends instead of a lot at one end. 

 

As per OP's request, I am assuming skill is adequate;if the skill isn't there to ski a 190 cm ski at 170 lbs, then a stiff 180 would be my rec over a soft 185, for safety reasons.

 

Even with skill, the race gs will be more "work" when not skiing fast and making smaller turns.  The racing SL will be less "work" than the racing GS when not racing, but it won't be any better at low performance skiing.

 

post #42 of 153


 

Quote:
Originally Posted by L&AirC View Post

So lets pretend that a person skis well enough to be on the PSIA Development Team (this is so you know we aren't talking about me anymore and there isn't an ability issue).  Is 5'7" and 170 lbs or 170cm and 77kg.  They are looking for a non FIS race ski for tooling around the mountain in.  Doing carving demos and maybe playing in the gates here and there.  Always on piste and groomers.  No crazy Super G speeds.  This isn't for any racing that requires a race suit or that has any gear regulations.

 

At what length would this person stop getting a benefit that isn't worth the effort being put in?  What would the most efficient length be?  At some point, the extra glide or float while on edge, just isn't worth it.

 


Just quoting this back out of the original post because it looks to me like mission creep has set in in a big way. I think that the skier you reference above is going to be skiing on a 170-177cm ski. Probably with close to an 80 waist too.

 

Rossi Classic 80 - 170

Dynastar 4x4 172

Kastle RX or MX78 176

etc.

post #43 of 153
Thread Starter 
Quote:
Originally Posted by epic View Post

Just quoting this back out of the original post because it looks to me like mission creep has set in in a big way. I think that the skier you reference above is going to be skiing on a 170-177cm ski. Probably with close to an 80 waist too.

 

Rossi Classic 80 - 170

Dynastar 4x4 172

Kastle RX or MX78 176

etc.

 

Gave up on herding the cats a couple days ago biggrin.gif, mainly because though it is outside of this thread, it's still good information.  I had to go back and read my original post a couple times so "I" could remember what I was asking.

 


 

 

 

post #44 of 153

Let me post some numbers here to prove my point about taper angle and turn shape.

 

Atomic  D2 FIS Gs

 

Length (I'll even use the shortest GS ski) 186cm Waist dimension = 67.5mm, Tail is 87mm

 

Atomic D2 Fis Slalom  length 165, Wasit dimeniosn 65.7mm, Tail dimension 102.2mm

 

The slalom tail is Apprx. 56% wider in the tail then the waist

 

the Gs ski is only 29% wider in the tail then the waist.

 

What do you think this does to the turn shape and how does this effect the versatitly of turn shape when comparing the 2 skis?

post #45 of 153

I would probably go for 175 cm length and probably an old Atomic SX12 or SX11 or maybe D2 GS, or Fischer RC Pro in about the same length if I was forced to ski only one ski for groomers.  (Atomic feels more solid, Fischer feels more).  I suspect I would love the Kästle RX too, if I ever got a chance to try one out.

post #46 of 153
Thread Starter 
Quote:
Originally Posted by Atomicman View Post

Let me post some numbers here to prove my point about taper angle and turn shape.

 

Atomic  D2 FIS Gs

 

Length (I'll even use the shortest GS ski) 186cm Waist dimension = 67.5mm, Tail is 87mm

 

Atomic D2 Fis Slalom  length 165, Wasit dimeniosn 65.7mm, Tail dimension 102.2mm

 

The slalom tail is Apprx. 56% wider in the tail then the waist

 

the Gs ski is only 29% wider in the tail then the waist.

 

What do you think this does to the turn shape and how does this effect the versatitly of turn shape when comparing the 2 skis?



 



Quote:
Originally Posted by oisin View Post




Hence my comment:"This is all based upon the assumption the skis shape ie turn radius is appropriate to the course." (contained within my comments that you quoted). If the radius of the ski were the only issue I don't think the original poster would have much difficulty answering his original question. It would simply be a matter of matching the designed turn radius of the ski to the radius of the turns most commonly set in the courses he races on. Of course we know there is more to this as well including the bend imparted to the ski by flexing which alters the turn radius as well. We also know that there are a variety of turn shapes. Not all or even most turns are an even curve of constant radius.  My point was that, everything else being within acceptable range, the things (other than FIS regs) that limit how short a ski might work are ability to maintain balance and the ability of the snow to support the ski.  As the snow becomes softer and the ski shorter a point is surely reached when the shorter ski is slower simply because of the depth of the groove it will carve in the snow. This is what I meant by "digging in", which is not as you point out, exactly a technical term. While a shorter ski might, with the appropriate designed radius, and a skillful athlete be capable of carving a clean arc in a gs radius turn, there could be a considerable amount of drag if the snow is not rock hard and so the ski is "digging in".

 

There's another issue related to ski length that I alluded to when i mentioned bending.  I used to race on 193 to 205 cm slalom skis that were relatively straight and yet they could be used to carve a turn because they could be bent in an arc. I think this is part of the issue with skis which are longer. Longer skis, to a point, can be more versatile if they can be bent to a variety of turn arcs. This is one of the great changes in ski design today that gets very little press. In years past skis often were quite stiff in order to produce edgehold. Today's skis are relatively soft flexing, lengthwise compared to older race skis. Damping technology has proven able to reduce edge chatter and maintain edgehold as well or better than stiffness, hence a relatively shorter  ski can be soft enough to be amenable to being bent to shape the turn. This is part of the reason why a 185cm gs ski is common where a 210 or 215cm gs ski was once standard.

 

Fwiw I have a pair of race stock 165 cm Elan SLX which are great for free skiing (on hard snow). The one thing they do not do very well is skid.

 



 

Atomicman & oisin,

 

I think you are both describing the same thing, sort of.  I was actually researching at Atomic's site the dimensions of a few skis to make sure 1) I was understanding and 2) everyone else was too.  I'm pretty sure I understand the meaning oisin meant by digging in and what Atomicman means by taper angle and going too much across the hill.  I've had the same discussion a few times with my race buddy.  I kind of look at these terms similar to when people say "knee angulation" when the knee doesn't flex laterally and what they really mean is femur rotation.

 

I compared the FIS 165 Slalom & 165 non FIS SL to the non FIS gs.  All pretty much the same length.  Also included the woman's FIS SL in 155. Threw in the shortest men's FIS GS for reference. It looks like this:

 

Ski Taper.png

 

You can see that the difference between the tip and waist and waist and tail is more severe on the SL than the GS. You can see three skis that are for this purpose the same length but all behave differently.  Because the non FIS SL has the greatest taper, it will turn the easiest and when you are carving it will "dig in" and send you across the hill if you aren't ready for it.

 

My reference point for that is my race buddy that, even in NASTAR, usually skis a 188 Fischer FIS GS (he's 5'6" and about 175# - I find that very annoying that he can do this), got a pair on non fis fischer 155 SL race skis and just for fun ran NASTAR with them.  On the second gate, he almost went into the trees.  He said they locked onto a carve and didn't want to let go.  He's a single digit platinum without a race suit.  It was from never skiing a short ski before and not a lack of talent.  He said  "The damn tail is like a rudder and won't let go!  You have to force it out."

 

So, because of the taper, the SL wants to carve and it takes more effort to release them than a gs ski, but it takes more effort to carve a gs ski because of the lack of taper.

 

Also, like oisin said, on certain snow you want a longer ski though sometimes a short ski is fine.  Soft warm snow an SL ski will dig in and the shorter the length (which equals more taper) the more it digs in or sends you across the hill.

 

So in my head the tip to waist taper, that comes on short SL skis, causes the front of the ski to dig in and sets the waist to tail taper up to hold on and not want to let go.

 

So I'm going to make a bunch more charts like the one above because the "MATH", that I so love, is telling me that for what I want the ski to do and how I plan on using it, if I had to pick from the chart above,  the non FIS 164 gs is probably the one.

 

Damn that was fun!

 

Ken

 

 

post #47 of 153

If you want easier freesking but with that type of shape i.e tip, width and tail proportionality how about something like a Supershape Magnum? 121/71/107 12.7m at 163. Nothing else really like it with that tight a radius that isn't a race orientated ski that i've seen. It's got more a bit more width in tail then the Kastle RXSL. Could even go up to the Titan if you wanted to try a bit of width too. 127/77/113 same 12.7 radius at 163.

post #48 of 153

for a compromise between GS and SL, you want non-FIS GS, yes, but at 175, not 164.   Magnum imho is a little shy on hard snow performance. 

post #49 of 153

One thing that is nice about the D2 line is that it is easier to initiate turns, and only stiffens in the apex of the turn.  Therefore, OP can go longer (and should) in that line while still having an easy time initiating turns.

 

Also depends on what kind of hill he's skiing... if he is on wide groomers of Vail, Whistler, or Tremblant, then he may want to go longer.  But if he's on tight/icy/steep hills in New England, a longer ski may not be what is right for the job.

 

All that said, I agree he should go for 175ish length

post #50 of 153
 
Quote:
Originally Posted by Atomicman View Post


If you read my post much earlier I alrerady covered all that. Slsom skis don't "Dig In" anymore then a GS ski unless you cause either to do so!

 

Also chatter is caused by pilot error. Poor technique Worng pressure in the wrong place in the turn,  in the wrong manner on the ski at the wrong time.

 

I ski some of the dampest skis around and on hard snow, with a lot of pitch, it takes very advanced technique to avoid chattering.

 

I also believe you are underestimating theeffect of tail geometry of a SL ski comapred to a GS ski.
 



 


Of course they do. It is a simple matter of pounds per sq inch of bearing area and the bearing value of the snow. Chatter can be caused by pilot error but it can also be vibration induced by variations in the snow surface and perhaps lack of torsional stiffness..Get a good edge with good alignment and with the ski tracking correctly and yet the ski kept releasing ego chatter.  Stiffness (usually longitudinal) was one method of addressing this, vibration dampening is another. Head Comps circa 1965 or so (I still have a pair) were among the first skis to attempt this. Head placed a sheet of rubber between the top two layers of aluminum to damp vibration and so allowed the ski to be much softer flexing which in turn allowed the ski to flex to follow terrain variations. For some reason this took a long time to catch on. You are correct though, it does take skill, even with modern skis but perhaps not so much as it used to. Skis are so much better than they used to be.

 

I think you make a good point with contrasting tail geometries. I really wasn't arguing slalom vs GS skis but the issue of length per se but of course a shorter racing ski will probably be designed as a slalom ski anyway so different geometries for different purposes (and courses). So its a moot point because FIS regs dictate that slalom sized skis will have slalom geometry and likewise for GS skis. I think its interesting to speculate what may have happened to race ski design without the FIS restrictions though.

 

post #51 of 153


I don't mean to confuse things but a wider tail means it has less taper angle and a narrower tailer means it has more taper angle. In other words the noarrower tail tapers more form teh waist towards the tail!
 

Quote:
Originally Posted by L&AirC View Post





 





 

Atomicman & oisin,

 

I think you are both describing the same thing, sort of.  I was actually researching at Atomic's site the dimensions of a few skis to make sure 1) I was understanding and 2) everyone else was too.  I'm pretty sure I understand the meaning oisin meant by digging in and what Atomicman means by taper angle and going too much across the hill.  I've had the same discussion a few times with my race buddy.  I kind of look at these terms similar to when people say "knee angulation" when the knee doesn't flex laterally and what they really mean is femur rotation.

 

I compared the FIS 165 Slalom & 165 non FIS SL to the non FIS gs.  All pretty much the same length.  Also included the woman's FIS SL in 155. Threw in the shortest men's FIS GS for reference. It looks like this:

 

Ski Taper.png

 

You can see that the difference between the tip and waist and waist and tail is more severe on the SL than the GS. You can see three skis that are for this purpose the same length but all behave differently.  Because the non FIS SL has the greatest taper, it will turn the easiest and when you are carving it will "dig in" and send you across the hill if you aren't ready for it.

 

My reference point for that is my race buddy that, even in NASTAR, usually skis a 188 Fischer FIS GS (he's 5'6" and about 175# - I find that very annoying that he can do this), got a pair on non fis fischer 155 SL race skis and just for fun ran NASTAR with them.  On the second gate, he almost went into the trees.  He said they locked onto a carve and didn't want to let go.  He's a single digit platinum without a race suit.  It was from never skiing a short ski before and not a lack of talent.  He said  "The damn tail is like a rudder and won't let go!  You have to force it out."

 

So, because of the taper, the SL wants to carve and it takes more effort to release them than a gs ski, but it takes more effort to carve a gs ski because of the lack of taper.

 

Also, like oisin said, on certain snow you want a longer ski though sometimes a short ski is fine.  Soft warm snow an SL ski will dig in and the shorter the length (which equals more taper) the more it digs in or sends you across the hill.

 

So in my head the tip to waist taper, that comes on short SL skis, causes the front of the ski to dig in and sets the waist to tail taper up to hold on and not want to let go.

 

So I'm going to make a bunch more charts like the one above because the "MATH", that I so love, is telling me that for what I want the ski to do and how I plan on using it, if I had to pick from the chart above,  the non FIS 164 gs is probably the one.

 

Damn that was fun!

 

Ken

 

 



 

post #52 of 153

On the matter of using a slalom ski in certain GS courses: I get the point about tail geometry dictating a certain kind of turn finish but that assumes you are skiing the same turn shape for each type of ski (I think). What if the racer adapts his technique to the ski so to speak? I mean if the turn were skiied with more of a "Comma" shape ie more turning effort in the top of the turn followed by earlier pressure release and a flatter arc thru the bottom of the turn, would this be viable? Edge angle and pressure release are dictated by body position and the movement of the body thru the turn so it seems to be at least theoretically possible. I really like my slalom skis at speed but balancing on such a small "sweet spot" can be a handful I admit and the inherent turning tendency of the ski geometry requires a lot of skill to release edge pressure without getting carried across the hill (or onto the keister) . But I think the question is worth asking anyhow. 

 

I've never entered a GS race with these skis (165 cm SLX WC) but I did do a race training course a few years ago with them and found myself getting launched a few times but I assume this was "pilot error" as Atomicman so aptly puts it. I remember a few people skiing Master's GS with short slalom skis before the regs took effect and they seemed to be having this kind of difficulty but I have to assume they were finding some advantages or they wouldn't have been trying it. My own experiences back then with short slalom skis in a GS course were with skis too soft flexing for my weight so I really was feeling them to be slow in the fast large radius turns (and even the smaller turns actually) . The feeling was of pushing a small radius arc thru a large radius turn ie skidding. I've always thought this was due to the (Rossignol 9sk) being too wimpy but then again I don't know. Free skiing with the slalom skis I find them to be very versatile as long as the snow is hard. They really are very difficult to skid though and you have to be right on them.

post #53 of 153
Quote:
Originally Posted by L&AirC View Post

 

So in my head the tip to waist taper, that comes on short SL skis, causes the front of the ski to dig in and sets the waist to tail taper up to hold on and not want to let go.

 

So I'm going to make a bunch more charts like the one above because the "MATH", that I so love, is telling me that for what I want the ski to do and how I plan on using it, if I had to pick from the chart above,  the non FIS 164 gs is probably the one.

 


Is this correct? My understanding was that tip to waist taper can change the initialization characteristics, but the waist to tail difference is what makes the tail want to dig in to the bitter end or let go easily. Thus a lot of modern rec carvers have big tips compared to waists, don't flare out again that much, so they tip into a turn aggressively but break lose nicely for bumps etc. No? I also have tried using a WC SL on Nastar courses, found it's fun, good technical practice, but not all that fast cuz they want to keep finishing their arcs, hate to glide and not all that happy with shallow edge angles. Possibly my sucky technique, but I'm faster on a longer radius rec carver.

 

I'm also confused about the notion of a 164 GS ski being a desirable thing. It may have the shape you like, but won't it be silly slow? Longer skis, like longer boat hulls, can run faster purely from the math, far as I know. Wrong there too? 

 

post #54 of 153

I believe you are correct on all counts except that longer skis are faster just because they are longer.

 

I believe the most important design element there is who is standing on them!

 

And i still can't used to the idea of "digging In" They may initiate more easily or begin a carve more easily becuase of the wide tip, but I just can't get used to the idea that they dig deeper into the snow by default.

post #55 of 153
Thread Starter 
Quote:
Originally Posted by beyond View Post

Is this correct?

 

th_dunno-1[1].gifBeats me.  That's why I said in my head.  Since Atomicman only corrected my use of smaller and larger taper (which makes no sense in my head), and no one corrected anything else, I'm guessing the rest was correct.

 

My understanding was that tip to waist taper can change the initialization characteristics, but the waist to tail difference is what makes the tail want to dig in to the bitter end or let go easily.

 

I thought that was what I said.  I did say the tip "sets" the tail and sets probably isn't the correct word for this.  How about:

 

"So in my head the tip to waist taper dictates if the front of the ski digs in or not and the waist to tail taper dictates how easily the tail will let go."  The more extreme the difference between tip and waist, the more it wants to dig in and the more extreme between waist and tail, the more it wants to hold on.

 

Thus a lot of modern rec carvers have big tips compared to waists, don't flare out again that much, so they tip into a turn aggressively but break lose nicely for bumps etc. No? I also have tried using a WC SL on Nastar courses, found it's fun, good technical practice, but not all that fast cuz they want to keep finishing their arcs, hate to glide and not all that happy with shallow edge angles. Possibly my sucky technique, but I'm faster on a longer radius rec carver.

 

The highlighted part is what I'm looking for.  I have the GSX to race with but in the beginning of the year, I like to work on skills more than speed and last year found that doing that with the SLX paid off.  The only downside was it was a 155 11M and I would have rather had a 165 (I think).

 

I'm also confused about the notion of a 164 GS ski being a desirable thing. It may have the shape you like, but won't it be silly slow? Longer skis, like longer boat hulls, can run faster purely from the math, far as I know. Wrong there too? 

 

I have a GS race stock ski.  It isn't FIS anymore but I don't care about that.  I was thinking of the 164 cheater gs for the training mentioned above instead of a 165 SL cheater or not race ski.

 



 

 

post #56 of 153
Thread Starter 
Quote:
Originally Posted by Atomicman View Post

I believe you are correct on all counts except that longer skis are faster just because they are longer.

 

I believe the most important design element there is who is standing on them!

 

And i still can't used to the idea of "digging In" They may initiate more easily or begin a carve more easily becuase of the wide tip, but I just can't get used to the idea that they dig deeper into the snow by default.


If in order for you to be carving the entire running surface of the edge needs to be on the snow.  In order for that to happen, the entire ski needs to be in a arc.  In order for the arc to happen the tip needs to dig in first to cause the ski to bend to start with.  I always figured that until the ski is entirely in an arc, the tip will keep digging in.  Therefore if you have a wider tip, you will dig in further.

 

I'm very comfortable being corrected on this because this is just what I've come to believe and isn't something I read or was taught.

 

Ken

 

 

post #57 of 153

I think the difference in our perception may be that the remainder of the edge once the tip is engaged follows the exact path that the tip begun carving.  This does not necessairly mean it is in the snow more, because edge angle determines the turn shape, so if the tip starts the ski carving and you increase or decrease the edge angle does the tip "dig in" more or less or does the ski bend into a tighter or less tight arc?


Edited by Atomicman - 7/17/11 at 7:32am
post #58 of 153

Atomicman, here's my justification for the longer=faster: Hull speed = 1.34 X Square root of LWL, where LWL is length of the waterline. The hull speed is the upper possible limit, obviously friction, drag, and other issues are separate. 

 

This is standard for any displacement hull, meaning anything that displaces water, or any other fluid. Snow is commonly modeled as a fluid. (Yeah, I know there are complex models of pow as a zillion particles, but for practical purposes, and compressed snow, hydrodynamics still rules.) So I assume it also works for packed, with the edges = waterline, because even if you're on ice, there's a layer of water between your ski's edges and the surface, created by the friction and down- pressure of the ski. Your ski dsiplaces/rides on that water. And if we're talking about "digging in," meaning leaving a track on packed snow, you're talking more serious displacement.  

 

So I'm arguing that longer is faster in skis because snow of any kind is still governed by the same laws of mechanics. Happy to be corrected here. 

post #59 of 153

I don't know if a wider tip digs in any more than a narrow tip, My point above is simply that a longer running surface (already quite narrow if the ski is carving on edge) has more surface area to bear the skier's weight and other forces on the snow hence the ski will not dig into the snow as much as a short ski. This is a negligeable advantage if the snow is quite hard (as is the case with water injected courses today since neither the short or  the long ski is going to make much of a dent in the surface. If the ski is quite short and the snow soft the ski is going to dig in or penetrate the snow to a greater degree than a longer ski since the weight will be concentrated on a smaller area. This could result in quite a bit of drag or frictional resistance that would make the short ski slower. The biggest advantage of the water injected courses that are becoming common today is to provide increased opportunity for those racing without a high start number. It used to be that the snow on courses was so soft that terrific ruts developed that often made it virtually impossible for anyone starting later than the first ten or so to win or even come close. Racing consisted of a slow climb up the ladder as a skier improved his or her FIS points in order to gain a better seed ie a crack at an earlier starting position. Skiing in the deep ruts back in the pack you really couldn't innovate much in terms of your line for example because you were pretty much locked into the line people before you had skied. A side effect of this I think has been to enable the use of shorter skis, particularly the slalom skis which today are ridiculously short (even with the FIS minimums) compared to what was standard 14 yrs ago.

 

 

By the way I'm not sure the hull speed analogy is applicable since it deals with the wave action of the displaced fluid and the overall hull shape. I don't think snow displaced by a ski edge exhibits any appreciable waveform although I could be wrong. Also the "hull" form of skis are virtually identical regardless of length. Even though the ski edge probably does ride in a thin film of liquid this is constrained by the snow behind it so I don't see any "bow wave " developing behind the ski tip but maybe some wizard aero/hydrodynamicist will chime in and correct me.


Edited by oisin - 7/16/11 at 10:33pm
post #60 of 153
Thread Starter 
Quote:
Originally Posted by oisin View Post

I don't know if a wider tip digs in any more than a narrow tip, My point above is simply that a longer running surface (already quite narrow if the ski is carving on edge) has more surface area to bear the skier's weight and other forces on the snow hence the ski will not dig into the snow as much as a short ski. This is a negligeable advantage if the snow is quite hard (as is the case with water injected courses today since neither the short or  the long ski is going to make much of a dent in the surface. If the ski is quite short and the snow soft the ski is going to dig in or penetrate the snow to a greater degree than a longer ski since the weight will be concentrated on a smaller area. This could result in quite a bit of drag or frictional resistance that would make the short ski slower. The biggest advantage of the water injected courses that are becoming common today is to provide increased opportunity for those racing without a high start number. It used to be that the snow on courses was so soft that terrific ruts developed that often made it virtually impossible for anyone starting later than the first ten or so to win or even come close. Racing consisted of a slow climb up the ladder as a skier improved his or her FIS points in order to gain a better seed ie a crack at an earlier starting position. Skiing in the deep ruts back in the pack you really couldn't innovate much in terms of your line for example because you were pretty much locked into the line people before you had skied. A side effect of this I think has been to enable the use of shorter skis, particularly the slalom skis which today are ridiculously short (even with the FIS minimums) compared to what was standard 14 yrs ago.

 

 

By the way I'm not sure the hull speed analogy is applicable since it deals with the wave action of the displaced fluid and the overall hull shape. I don't think snow displaced by a ski edge exhibits any appreciable waveform although I could be wrong. Also the "hull" form of skis are virtually identical regardless of length. Even though the ski edge probably does ride in a thin film of liquid this is constrained by the snow behind it so I don't see any "bow wave " developing behind the ski tip but maybe some wizard aero/hydrodynamicist will chime in and correct me.



This is what I originally thought was the main reason, but from further discussions came to believe that, though it's a factor, the turn radius and ski stiffness is more of one.  This is the same reason why speed skates are longer than hockey or figure skates.  Also one of the reasons why today's skis can be shorter and carry the same "float" characteristics of yester-years long straight skis.  I used to have a pair of Metron B5 in 162 and proved to the owner of 188 races skis that I had more surface area on the base than he did.

 

When you tip a ski on edge, I don't think the forces are applying pressure straight into the hill but down the hill.  The pressure is still acting on the base of the ski and the track that is left from carving is a result of that and not so much pressure pushing into the mountain (more from down the fall line).  The base of the ski becomes the platform that the skiers weight presses against and not the edge.  There were endless discussions on this last summer in the Infamous Virtual Bump threads.http://www.epicski.com/forum/thread/94712/the-virtual-bump-real-or-fiction

 

If you bend a ski while it is on its side (in your basement or shop) to get the entire edge touching, you'll see that you'll probably break it before the entire edge touches the surface at the same time (yes I tried this with cargo straps and could never do it http://www.youtube.com/watch?v=BZZu2ikz11Q&feature=channel_video_title).  This is why I say that if while on edge, the part of the ski that is under my foot (last place to touch),  is in contact with the snow (making the platform), then the tip of the ski must be making more contact because it is still wider; not as much as when the ski isn't bent, but still wider.

 

This is also the thinking that started me to originally post and ask the question; how do you determine when the ski becomes too long for the task at hand.  Speed skates (from a quick googling) go from 15" to 18".  I'm betting the decision maker there is weight when picking between 15" and 18".  Skaters don't have a fall line to contend with or much of a base.

 

Ken

 


Edited by L&AirC - 7/17/11 at 5:43am
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