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Five point skis

post #1 of 14
Thread Starter 

In the wide ski/sidecut thread, five point skis keep coming up.

Anyone care to discuss how they ski, what conditions/terrain they excel on, and how that works?

post #2 of 14
post #3 of 14
Quote:
Originally Posted by LiquidFeet View Post
 

In the wide ski/sidecut thread, five point skis keep coming up.

Anyone care to discuss how they ski, what conditions/terrain they excel on, and how that works?

 

Which ones have you skied, in what conditions,  and what was your reaction?

post #4 of 14
Thread Starter 

i have not skied them.  That's why I am asking.  Not interested in marketing claims.

post #5 of 14

As with all other skis with taper and tip and tail rise, the five point shape interacts with the other components of the ski's build and especially the flex and amount of rise fore and aft of the contact points. What it all does is basically ensure that the fore and aft points are disconnected when on top of the snow but can be activated while under the snow. One bennie of those shapes is that they reduce tip and tail pressure when the ski is submerged thus, the ski can 'smear' to some greater extent while inside the snow. A disadvantage I guess might be that that you cannot get firm engagement much past the contact points. I'm not sure that matters a heck of a lot given the types of ski that this feature is usually found on.

 

My recent review of the the Dyastar Powertrac 89 shows that a 5pt can work very well on even a std "all mountain" shape assuming it is as well executed as that one is.

 

SJ

post #6 of 14
Thread Starter 
Quote:
Originally Posted by SierraJim View Post
 

As with all other skis with taper and tip and tail rise, the five point shape interacts with the other components of the ski's build and especially the flex and amount of rise fore and aft of the contact points. What it all does is basically ensure that the fore and aft points are disconnected when on top of the snow but can be activated while under the snow. One bennie of those shapes is that they reduce tip and tail pressure when the ski is submerged thus, the ski can 'smear' to some greater extent while inside the snow. A disadvantage I guess might be that that you cannot get firm engagement much past the contact points. I'm not sure that matters a heck of a lot given the types of ski that this feature is usually found on.

 

My recent review of the the Dyastar Powertrac 89 shows that a 5pt can work very well on even a std "all mountain" shape assuming it is as well executed as that one is.

 

SJ

Thanks, SJ.  Checking myself for understanding below...

 

1. --The narrowing/tapered tip and tail are not engaged when the ski is edged on hard snow since they don't reach that hard surface; they are waiting for another situation to go into action.  I'm pretty sure I've got that right.

 

2. --When the ski is partially or wholly submerged in powder or crud or spring slop, the tapered tip and tail function to lengthen the active surface area; what they do is spread out (or absorb) some of the pressure that builds along the entire ski, which is why you say they "reduce tip and tail pressure."  Have I got that right?  I'm feeling fuzzy on this part.

 

3. --#2 makes the ski is happier to smear when embedded in snow, because the widest contact points no longer have concentrated high pressure on them; they let go of the snow and don't dig in.  Right?

 

I read the review of the Dynastar 89.  Interesting.

I know the stuff above might sound tedious, but I want to understand.   

post #7 of 14
Quote:
Originally Posted by LiquidFeet View Post
 

Thanks, SJ.  Checking myself for understanding below...

 

1. --The narrowing/tapered tip and tail are not engaged when the ski is edged on hard snow since they don't reach that hard surface; they are waiting for another situation to go into action.  I'm pretty sure I've got that right.

 

2. --When the ski is partially or wholly submerged in powder or crud or spring slop, the tapered tip and tail function to lengthen the active surface area; what they do is spread out (or absorb) some of the pressure that builds along the entire ski, which is why you say they "reduce tip and tail pressure."  Have I got that right?  I'm feeling fuzzy on this part.

 

3. --#2 makes the ski is happier to smear when embedded in snow, because the widest contact points no longer have concentrated high pressure on them; they let go of the snow and don't dig in.  Right?

 

I read the review of the Dynastar 89.  Interesting.

I know the stuff above might sound tedious, but I want to understand.   

 

While I would have framed some of this a bit differently, I agree with SJ more than I differ (an unusual state of affairs ;)). With respect to #2, consider the typical "5 point" design characteristics which are the result of a design archetype that is a reverse sidecut ski with a sidecut "bite" taken out near the middle, and usually a flat or cambered mid section added. So you get:

 

- ski with the fat part of the tip and tail moved in toward the foot.

 

- often significant, and at least modest tip and tail rocker (both length and rise). If the ski has camber, it is usually roughly aligned with the taper point. Some designs skip the tail rocker (or mostly skip it) but would be described by most as 5 point nonetheless.

 

- the length of sidecut is usually fairly short. For intuitively obvious reasons, this needs to be coordinated with the tip/tail taper. This is largely a result of that design archetype for these hybrid designs --- they try to hold the soft snow benefits of reverse/reverse designs while incorporating enough edge hold and intrinsic firm snow radius to be useful across a wide range of conditions.

 

One effect of this is that the surface area of the ski is concentrated closer to the foot than in a traditional design. This gives you more soft snow support and control from underfoot. And engages more of the turn from underfoot in deep snow. But still leaves the tips and tails in play for fore/aft support and guiding the entry and exit of more arc-ed soft snow turns (note that a reverse/reverse ski, while smeary, is also capable of more arc-ed powder turns than a traditional cambered ski).

 

These designs are super common today. As an instructor, I'd think you'd want to demo a pile of them since they are what many of your clients will end up skiing. And they do want a slightly different technique (or in deference to certain instructors - a slightly different different blend of skills applied to them)

post #8 of 14
Thread Starter 

That's why I'm asking.

post #9 of 14

Also, to be clear  - I am not claiming 5 points rule everywhere every day. Every design space has its uses. And a point where it shines the most. A 5 point design will not out-slalom a slalom ski on ice. Just as a race derived ski will never approach the utility of a well designed fat 5 point or reverse/reverse ski in powder. The better 5 point designs I have seen are striving for a best of both worlds under the broadest possible range of conditions degree of versatility. IMO these are as good or better than traditional sidecut/cambered skis under almost all of the conditions I normally ski. But even Keith at Praxis - a company originally launched on a full reverse/reverse design - has designed an 82 wide GS style ski for dedicated hard groomer use...

post #10 of 14

LF:

 

I think you had your points pretty well figured out. Not quibbling at all about semantics re: #2, but in the shallow snow/crud or spring slop thing, here is what I found as it relates specifically to the Dynastar. I use this as an example b/c it's a category where 5 point has not been notably present (although there is a bit of what I guess you could call "4 point" out there). IAC, there are a lot of good skis in this range with varying degrees of rise but conventional tips and tails and I have compared the PT89 against a good number of them by now.

 

When the ski is trying to cut through this stuff, the pressure from the snow builds up against the tip and pushes back against the ski and tries to bend it so that the ski will come up over the goo. In inconsistent snow this will cause the "Porpise" effect or the feeling that the tip is climbing then diving then climbing again all in very rapid succession. There is also the sensation that the tip is getting yanked hither and yon and both of these things are tiring. With less resistance due to the sharp taper, the tip of the PT does not get pushed around nearly as much. There are other ways that various companies try to mitigate this feeling and some do it better than others. Naturally, everything is relative but at this time, the 5 point PT 89 seems to handle mixed and inconsistent snow better than others in the same width range.

 

SJ 

post #11 of 14
Thread Starter 

Thanks, SJ.  My only powder specific ski is a Scott P4.  It's a twin tip, burly in flex, and fully cambered.  I need to move on.

But then I'm normally at a mountain that doesn't see deep pow very often, and when it comes it blows into the tight trees.

post #12 of 14
Quote:
Originally Posted by LiquidFeet View Post
 

But then I'm normally at a mountain that doesn't see deep pow very often, and when it comes it blows into the tight trees.

 

So why even chase a 5-point design, then, unless it's to demo and experiment, and maybe make recommendations to your students?

 

IMO, they are really made to come out and play when it gets deep.

post #13 of 14
Never mind.
Edited by clink83 - 3/31/14 at 9:37pm
post #14 of 14

Couple of non-authoritative thoughts:

 

1) Historically we're used to ski width measurements being reported with three figures representing essentially the head, waist, and toes of the ski. When the new designs came out, as described above, the spec sheets started featuring five numbers instead, representing head, shoulders, waist, hips, and toes, if you'll allow the metaphor. Is that the origin of the term "five point"? I have been assuming it was.

 

2) Consider skiing in soft snow that's at least as deep as the ski is wide. It feels to me as though when the ski is in this snow, the tapered tip exposes more surface area to the snow very gradually in accordance with the tipping, and introduces the ski to the snow's resistance - and thus to its own increasing bend - in a gentle, predictable way that's easy to modulate. Of course this works in conjunction with the very gradual tip turn-up, over a long distance, that you usually find on this kind of a ski. Contrast this to what happens with a ski whose sidecut extends all the way to the very tip, as is the case on a Rossi E88 or a Nordica Fire Arrow, for example. In that case you tend to have a more on/off feeling as the ski is tipped and it engages with the snow. Maybe this is what some of the other posters were trying to describe, and I just didn't latch on.

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