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The "lost" ski waist width: 70-79mm - what's the point? - Page 4

post #91 of 104

I have yet to find a day when my 76mm Elan magfires don't feel up to task - In very short turns, they don't have the lightning quickness of a sub 70mm ski, but everywhere else, the performance is nothing short of heroic.  Even last Saturday, when we had a very icy day here on the east coast, they performed beautifully. 

 

I think we also get back to the quality of the tune - with an excellent tune, the skis in the mid 70 range perform incredibly in an amazing range of situations, with vastly fewer sacrifices than a sub 70 or 80 plus ski will present. 

post #92 of 104

 

Quote:
Originally Posted by sjjohnston View Post

 

In the note about boot sole width, I was countering the notion that there is no gain in "efficiency" (or leverage, bite, edge hold, whatever) as the ski becomes narrower than the boot sole, i.e. disagreeing that there's a point of maximum "efficiency" when the ski is the width of the boot sole. As a matter of simple physics, this isn't the case. Completely agree. I may have misinterpreted your point, but was addressing a problem with the analogy: skates gain efficiency because of both their relation of sole width to edge width, and their stand height. But as a skater my sense is that the stand height actually slows the reactivity of the edges, like balancing a top. As you reduce the height of the top, it gets harder to balance. If you were to put a single blade directly from sole to ice, say 20 mm, suspect you would actually be "overefficient," in the sense that small changes in your CM and foot tonus would produce large changes in your edge angle. (You'd also boot out almost instantly.) I just think it's more complicated than simply increasing efficiency. 

 

Obviously, other things happen as you narrow a ski, which combine to make something around 65 mm the lowest you want to go for ordinary skiing. These include the problem of keeping the boot off the snow, or "boot out," which was among the points I specifically made in my post above. Well, yes, but the narrowest currently made ski I know of, the Laser, is 63 mm, and you are highly likely to put a plate on it, which will increase leverage and reduce boot out. Back in the day, when we all skied stuff in the high 50's, and didn't use plates, we just didn't achieve as high en edge angle as we routinely hit today. Like a classic CC ski.

 

Whole 'nother subject, but on the "wider = smoother" point, as it involved death cookies (or rocks, ruts, roots and other things that may or may not start with "R"): I don't agree with this either. If you strike a death cookie 10mm off center in a wide ski or a narrow ski, the effect will be approximately the same. I can't see how this works; a wider ski of the same length has more mass, and that means more inertia, more resistance to displacement. Also basic physics. Could you show how inertia is irrelevant? If you strike a death cookie 40 mm off center on an 85 mm ski, it will be consideraly less "smooth" than if you did the same thing with a narrow ski, because you wouldn't strike it at all on the narrower ski. The original example was about hitting something, period. I could avoid it on my old pasta thin tele skis too, but so what? If, for some reason, you want to compare what will happen if you strike a death cookie 30 mm off center on a 65 mm ski vs. striking a death cookie 40 mm off center on an 85 mm ski, I think I'd prefer the narrower one, for the same reason I'd like to hit a death cookie as close to straight on as possible. Assuming the force  exerted by the death cookie on the ski is the same in each case, the torque on your leg will be 1-1/3 times greater on the wider ski. Not sure of the math here (been a while since physics, seem to recall r wasn't actually a linear distance but a radian), but to me real problem is, aren't you assuming a simple rotational system with zero mass, so that resultant torque actually getting to your leg is simply a function of r? Put another way, you may be right about torque per se, but IMO you're ignoring other physical attributes of the system. Also common experience; you won't find many skiers who find wider skis less stable or harder on the legs in rough snow.  

 


Edited by beyond - 3/5/2009 at 04:32 pm


Edited by beyond - 3/5/2009 at 04:51 pm
post #93 of 104

 

Quote:
Originally Posted by Noodler View Post

 

dawg - great post.  Points well taken.  I hadn't really even considered that it's really the 80-89mm widths that could be considered "lost".

 

I think this is all leading up to the inevitable situation - I need to ski the skis back to back in variable conditions 

Key concept here: The "lost width" is the one that's between whatever skis you feel satisfied with. For me, it's 72-87 mm, for a guy who lives in SLC, it could be 95-110 mm. Fer instance, last year skied Sun Valley and Jackson Hole back to back, couldn't ask for more varied conditions/terrain both within and between places, found I spent most of my time on an 88 (SV) or a 105 (JH). If I lived in Ketchum, and had to stick with two, I'd own about the same two widths I use mostly back east, 68 and 88. If I lived in JH, I'd have a 85-88 and something traditional cambered in the 105-110 range. If Tahoe, a 72-75 and a rockered 110-115. No one-size-doesn't-fit-all. 

post #94 of 104

Ski Width and "Over Efficiency"

 

My general point was, the narrower the "ski" (we start to call it a "skate" at some point), the eaiser it is to tip it on edge. This holds true in ranges of ski width wider than the boot sole and narrower than the boot sole. As you note, as it gets narrower, it starts to get too easy to put on edge, and you find yourself putting it on edge when you don't even want to: sometimes more succinctly described (for those of us who aren't very good skaters) as "falling over."

 

Put another way, purely in terms of the mechanical system that connects your leg to the base of your ski, the boot sole width is not a factor. So long as your binding is inelastically coupling the boot to the ski, the boot sole width doesn't even exist as a variable.

 

Once you start hitting something on the ground - that's a different issue.  Though, I will note, the issue isn't so much the boot sole width as the width of the boot shell, or (more basically) the width of your actual foot.

 

Death Cookies

 

I think the moment of inertia of a ski around its long axis is de minimis.

 

Bottom Line

 

A wider ski is "more stable" only in the sense that one uses "stable" as a synonym for "more difficult to put on edge." That's a positive, when you aren't in control of your edges, and a negative when you are. When skiing on hard-packed snow (rough or not) and working to hold an edge, a narrower ski is more controllable, and feels more stable and less hard on the legs. You won't find many WC racers running the Hahnenkamm on 85 mm skis.

post #95 of 104

 

Quote:
Originally Posted by sjjohnston View Post

 

Ski Width and "Over Efficiency"

 

My general point was, the narrower the "ski" (we start to call it a "skate" at some point), the eaiser it is to tip it on edge. This holds true in ranges of ski width wider than the boot sole and narrower than the boot sole. As you note, as it gets narrower, it starts to get too easy to put on edge, and you find yourself putting it on edge when you don't even want to: sometimes more succinctly described (for those of us who aren't very good skaters) as "falling over."

 

Put another way, purely in terms of the mechanical system that connects your leg to the base of your ski, the boot sole width is not a factor. So long as your binding is inelastically coupling the boot to the ski, the boot sole width doesn't even exist as a variable. Sounds reasonable, thanks for the clarification. 

 

I think the moment of inertia of a ski around its long axis is de minimis. OK, you sound like an engineer, and obviously I'm not. But this summer, my SUV was pushed into the path of a guy doing 70 mph, he hit us pretty much dead on broadside. Not a lot of rotation around the axis. But as the investigators said, "your SUV trumped his compact. If you'd been driving anything smaller, you'd be dead." Translated, to my Physics I understanding, "The tendency of an object to resist change varies with its mass" (setting aside friction.) Does Newton only apply to non-rotational systems like heavy boxes or cars? Or is a ski just a simple rotational system? IMHO, this feels like you're hitching your entire argument to a very simplified model that doesn't really cover all the variables. But y'know what? I'll go ask a buddy who's an engineer and he'll probably set me straight. 

 

Bottom Line

 

A wider ski is "more stable" only in the sense that one uses "stable" as a synonym for "more difficult to put on edge." Agree that wider skis are also slower to put on edge because more force required. But everyone I've ever known would use stable to mean resistant to change, as in "that's a really stable tail." They're all deluded and it's really just a slow tail to move (but not because of inertia)? That's a positive, when you aren't in control of your edges, and a negative when you are. By your argument, there are plenty of superb skiers here who apparently "aren't control of (their) edges" because they wouldn't agree with your definition. This sounds circular. When skiing on hard-packed snow (rough or not) and working to hold an edge, a narrower ski is more controllable, and feels more stable and less hard on the legs. You won't find many WC racers running the Hahnenkamm on 85 mm skis. Agree somewhat about less hard on the legs, that's an isue of how much force is required to lever the edge up. (Assume you don't think dampness exists as a relevant variable either.) And "controllable" might well be about efficiency, thus above. But how much of their ski's  "stability" is because of the width and how much because of the length? If WC racers could only use 170 mm skis, would they choose 68 mm wide or 78 mm wide? 

 

post #96 of 104

No, I'm not an engineer! But I did stay in a Holiday Inn Express last night. Okay, no, I didn't even do that.

 

On the "death cookies" thing, I was just looking at the basic characteristic that is different between a wider and a narrower ski, which is ... width. That is, taking "all other things to be equal." The wider ski has a greater moment of inertia, just because it's wider (moment of inertia varies with the mass, and how far away from the axis it is). But the moment of inertia around the long axis of ski is really miniscule, whether the ski is wide or narrow. In other words, I wasn't saying that the rotational inertia of the ski is the key factor, but the opposite: it's so small, it's not a factor at all, at leats not in a system where you'rer dealing with 190-lb skiers traveling 30 or 40 miles per hour.

 

If' the ski is heavier , that would be another factor. Of course, it's very easy to make a narrow ski as heavy as a wide ski, or considerably heavier, if you want. Indeed, I think the ski makers put a fair amount of effort into making their skis lighter, while maintaining other desirable characteristics, like torsional rigidity and resistance to breaking in half. So ... since weight is not something that can only be achieved with width, I really think it should be treated as a separate characteristic.

 

By the same token (and since I just aluded to it), a ski that's not very torsionally rigid would also be less disrupted by death cookies, as it would simply twist to accommodate them. Again, it would be very easy to make a ski (wide or narrow) that's less torsionally rigid than what we're all skiing on: just stop putting so darn much effort into making them more torsionally rigid.

 

Positive characteristics can be negative in some situations. That's the case in what I mentioned as the "bottom line." Every skier, no matter how superb, is not in control of his edges sometimes ... if that weren't the case, nobody would ever fall, and every superb skier would be a perfect skier. If you could somehow keep a skate blade from sinking into the snow, even the most superb skier would look fairly discombobulated trying to ski a mogul field on it.

post #97 of 104

 

Quote:
Originally Posted by MoreCowbell View Post

 

I have yet to find a day when my 76mm Elan magfires don't feel up to task -

 

This thread has made me realize I don't have ANYTHING between 71 and 79.  I don't feel any need for it, but now want it, just because I don't have it.   Make sense?

post #98 of 104

That not only makes sense, it's the fundamental basis of the American consumer economy.

post #99 of 104

Humm, I also don't have anything between 81 and 99, and nothing over 99 at all.   Pretty big holes there eh?.  I haven's skied in more than a foot of fresh in the past 10 years, but I've gotta get something else that isn't exactly 99 + and - just to have that too... For my country of course

post #100 of 104

Thank you!!! Someone has to get the economy rolling again!

post #101 of 104

This is the precise waist width I am looking for.  I am a second year skier, ski midwest (Mad River Mtn, OH and Bittersweet, MI), probably a modest level 6, 28 years old, 5'10 160lbs, wanting to improve my technique and carving.  I don't ski fast and don't look for the bumps.  I may get stationed out in Utah next winter and would anticipate cruising the groomers and looking to improve my technique with lessons in soft snow conditions, so some thing in the mid-high 70's is my focus.  I am looking at:

 

Head Monster iM 76

Volkl AC20

Fischer RX Red Heat

Atomic Nomad High Noon

Dynastar Legend 4800 Fluid

Dynastar Contact 4x4

Nordica Hot Rod Overdrive

Elan Mag 10 Ti

 

All of these are 74-76mm in the waist and look to be great candidates for soft snow frontside groomers.  Once I start to venture off-piste, I think these skis will allow me to and then I can move up to something over 90mm if I get more aggressive.  I think a 2-ski quiver for UT would be nice to have, but if the wife "advised" only a 1SQ, I would probably look for something in the mid 80's (all of my info and conclusions are drawn from epic and expertskier.com reviews - thanks).

post #102 of 104

 

Quote:
Originally Posted by sjjohnston View Post

 

Of course, if you used a skate blade in anything like "ordinary" ski conditions, you'd find yourself immobile, standing on the equivalent of a stake in the ground.

 

Depends on where you live and ski, and what kind of a season you're having. I have skied MANY days in my career on conditions where an ice skate blade would have been very welcome. No kidding. Yellow ice, gray ice, blue ice, white ice. Seen 'em all. I surmise that either you are from the West or you have one of those jobs where you can pick your days.

post #103 of 104
Thread Starter 

OK, so I'm still growing in my appreciation of this sport.  My original post was probably way too oversimplified (surprising coming from me being such a gear head ).  I had the opportunity today to ski 4 of my skis back-to-back and switch them easily (had my car parked in a beach spot at A-Basin).

 

Clearly, categorizing skis merely by their waist width is missing a whole host of other variables that absolutely play into the equation regarding what ski is suitable for which conditions.  Running very different skis back-to-back provides a great experience to make some concrete observations regarding the pros and cons of each ski.  However, you just can't make any blanket statements about what skis of certain widths can or can't do.  So some mea culpa on my part.

 

So if anyone's interested in my observations today, here they are (note that the specs are my measured specs and not the published specs).  Conditions today at A-Basin were basically dust on crust, but there really wasn't any boilerplate.  As it warmed up the skis were able to bite into the slope very nicely.

 

Ski #1 - 2005 Elan S12 (166cm, 113-66-99, ~14m sidecut) - turns on a dime, incredible power and rebound energy, great edge hold.  Heavy skis with a burly construction (very thick, tons of camber, lots of metal).  These skis were great while I was fresh and willing to put the work into them - easy to get great high edge angles at slower speeds (<30 mph), but the sidecut is too deep for higher speeds to really lay them over (they just turn too quick and generate so much force I can't hang with them).  I can't see using these skis for my typical day of skiing at the speeds I normally ski - I just can't relax on them unless I'm rolling slower (like skiing with lower level friends on groomers all day).  I'm going to keep them until I can rationalize replacing them with something like the Elan Speedwave series stuff.  I also had a tough time getting them to carve longer radius turns.  This is a case where there may be other skis this narrow that are more versatile, but the pair I happen to have are not.

 

Ski #2 - 2005 Stockli Stormrider XL (171cm, 116-75-102, ~18m sidecut) - the contrast between the Stocklis and all the other skis was huge.  I've said it before and I'll say it again - these skis feel like velvet on the slope.  They're incredibly damp without being lifeless.  They were comfortable doing multiple turn sizes and shapes - and I can really lay them over at much higher speeds and feel completely comfortable.  At the speeds I normally ski at (30-45 mph - as shown by my GPS) these skis have just the right amount of sidecut and stability when the conditions are hard groomers.

 

Ski #3 - 2004 Volant Machete FB (176cm, 128-94-115, ~22m sidecut) - This is just a bulldozer of a ski and it eats crud for breakfast.  They're so heavy that there isn't much you'll run into on a mountain that will deflect them (maybe a chairlift tower ), but with that stability comes a very noticeable decrease in quickness - you just can't throw these babies around.  I'm keeping these around as I probably won't get a decent sale out of them and they're a great tool for when the conditions are killing anything else I could throw at them.

 

Ski #4 - 2006 Elan M999 (181cm, 126-99-116, ~24m sidecut) - This is the original edition of the M999 that has a very soft tip and tail while still being very firm underfoot.  Although these skis are wider than the Machete FB they felt quicker (they're lighter) and easier to move them around the mountain.  They held just fine on the hard stuff, but the tips and tails were flapping in the wind.  It was a little disconcerting to look down and see the tips just flapping like crazy.  I also really noticed the major change in effort required to get these skis on edge.  Previously I haven't really noticed this in softer conditions, but running them at high edge angles for an entire run down a groomer was a workout.  I wanted to see if I could ski them just like my skinnier skis and found that although I could (mostly) they clearly wouldn't be my choice for a groomer day.

 

 

So I guess I'm just going to be a big quiver skier.  I didn't get out on anything with a waist width in the 80s today.  That's the next big test - to compare my "winner" of the day, the Stockli at 75mm, against my Elan M777 (at 85mm underfoot) and my Elan 888 (at 89mm underfoot) - first on groomers then hopefully in some soft snow.  I want to see if I can turn the larger skis almost as easily while they're much better at handling the soft stuff.  I'm especially excited to get out on the Elan 888 since it's a bigger ski with a larger amount of sidecut (they have a fairly wide tip).  On paper they should be fairly good at carving on groomers while still having enough float to do decently well in 3D conditions.

 

 

post #104 of 104

I doubt there is one do-it-all ski: if so, then everyone other company would be out of business.  Too many factors: what people ski, where they ski, how fast they ski, how big they are, how well they ski, what they like a ski to feel like.  With that said, MY close to do-it-all ski would probably a Nordica Enforcer, as it is does everything pretty well.  Wide enough to float, carvy enough to be fun on groomers, responsive, decent in bumps, some energy: there aren't many skis like that around (the Kastle MX98 is another that falls into that category).  I wouldn't be completely happy on deep days, or completely happy on firm days, but obviously could manage enough to have a good time. 

 

Just have to try and see what you like, and if you are picky, get 2 or 3 pair.  

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