Nordic Rocker

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Johnny

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Nordic Rocker

Postby Johnny » Wed Dec 13, 2017 1:31 pm

Nordic Rocker.jpg
Asnes Ingstad BC skis, showing traditional camber (top) and Nordic Rocker once weighted (bottom)


Source: Johnny / LilCliffy
A cross-country ski with rocker tips? Really?

When holding new Nordic Rocker skis together, you can see and feel a normal XC ski with traditional camber. Skis touch near the tip where they should. No real signs of rocker yet. But step on the skis or press them against each other and the Nordic Magic kicks in. With some pressure, the tips open up and reveal a rocker. The tips open like a true rockered BC ski, hidden until you apply pressure on the ski. How cool is that?

The Nordic Rocker technology by Fischer was first announced in 2011. It was first available on their S-Bound and Spider series. "Nordic Rocker Camber: No, the tips and tails don’t have the obvious splay of alpine and tele skis with rocker. But the tip does rise over traditional skis when weighted. This aids in climbing, as the tip will climb up out of the snow, and in turning in soft snow."

Here is an excerpt from a technical paper: (Google-translated)

Image

"Skis with a Nordic Rocker design are unmatched in deep and fresh snow. They are easy to manage due to increased ski tips; they return faster and effortlessly due to the redistribution of pressure. Nordic Rocker design is characterized by two digits. For example, in a 10/15 design, the digit 10 indicates how many millimeters the toe is raised when the skis are weighted. The number 15 indicates the number of centimeters on which the area of ​​greatest pressure from the toe to the heel during the load is displaced. Thus, at the moment of compression of the ski, the tip is unloaded and the ski is not buried in the snow, providing good flotation."

At the present time, only a few manufacturers are making skis with Nordic Rocker, mostly Fischer, Rossignol and Asnes.

Nordic rocker or just rocker?

"Nordic rocker" is not the same thing as rocker. A rockered profile is the opposite of a cambered profile. And although some Nordic skis do have a truly rockered tip- skis with "Nordic rocker" have a traditional full-length cambered profile (i.e. the unweighted contact points are at the tip and tail).

A fully rockered ski would offer zero true Nordic "kick" and would be extremely inefficient as a XC ski.

A Nordic ski with a truly rockered tip gives up some kick and glide efficiency in exchange for "early tip rise" (i.e. causes the tip to rise towards the surface of the snow). Early tip rise facilitates a number of things including trail-breaking in deep, soft snow; downhill turn initiation; and uphill climbing.

Traditional Nordic skis have a full-length camber for a number of good reasons- not the least of which is to maximize the glide length/surface during the glide phase of classic kick & glide XC skiing.

A ski with "Nordic rocker" appears to have a traditional Nordic camber profile- with no tip rocker. However- when a ski with Nordic rocker is fully weighted (i.e. the camber is fully compressed), the most forward contact point of the ski moves back and the tips open up (i.e. appear "rockered").

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Different contact points on different Nordic Rocker skis


I have been examing the tips- both weighted and unweighted-of a number of my BC Nordic skis:

1) 2006-2009 Madshus Eon: no Nordic rocker
2) 2001-2013 Karhu XCD 10th Mtn/Madshus Epoch: no Nordic rocker
3) 2001-2013 Karhu XCD Guide/Madshus Annum: no Nordic rocker
4) 2015 Asnes Combat Nato/Ingstad: no Nordic rocker
5) 2015 Fischer E-99: considerable Nordic rocker
6) 2015 Fischer E-109: considerable Nordic rocker

Fischer claims that the current S-Bounds all have Nordic rocker. I have not tested any of them in several years. Would be great to hear from other skiers with S-Bounds and get their observations regarding Nordic rocker.

I was actually surprised by how much my E-99/E-109 tips open up once they are weighted. (BTW both of these skis open up at least twice as much as the 10cm shown in Fischer's diagram below).

Both the E-99 and the E-109 are cambered like a classic XC ski- but the opening of the tips is very different from any BC-XC ski I have ever owned. I will be skiing on them this winter and will be able to compare them to my other skis that do not have "Nordic rocker".

When kick and gliding, making your way through deep snow, the Nordic Rocker will sure help stability. With light pressure on the front ski, the rocker will keep your tips from sinking, they will tend to stay naturally on top of the snow while providing enough support for effective and straight striding. The same applies when climbing and traversing, making the ascent more stable and safer due to the fact that the amount of the snow over the ski should be much lower. Rocker tips always keep you from sinking on the uphill. And on the descent, turn initiation is much easier than any other cambered ski.

The idea of adding either true rocker or, Nordic rocker to a backcountry Nordic ski- intended for deep, soft snow- opens up some very exciting possibilities. For example, ski manufacturers have been building BC Nordic skis with significant sidecut for some time- to offer a tighter turning radius. While this is awesome for turning on a dense base, it can make for a "squirrely" XC glide, and it can also significantly reduce surface area/flotation on narrow and mid-width skis. What about taking a mid-width Nordic ski, add tip rocker (or Nordic rocker), but reduce the sidecut. A ski with this design would have a longer turning radius- than a similar ski with more sidecut- but it would track straighter, offer more flotation, still offer decent turn initiation, and should still be manoeuvrable on soft snow.

Just like computers and synthesizers in the 70’s, it’s still too early to see how people will react, and what use they will make of such a new technology. But this is probably the most promising (and exciting!) ski technology on the market right now. This is truly something new, which could change our perspective on XCd and xcD skis for the years to come.
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