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ROCKER 101: A Brief History of Rocker + A Glossary of Terms

ROCKER 101: A Brief History of Rocker + A Glossary of Terms

Editor’s Introduction:

Guy walks into a ski shop, tells the sales person that he’s looking for some new skis. The rest of the conversation goes like this:

“Rocker rocker rocker rocker rocker rocker rocker.”

Girl walks into the Snowsports Industry of America Tradeshow in Denver, hears this echoing throughout the entire convention center:

“Rocker rocker rocker rocker rocker rocker rocker.”

You get the point.

Rockered skis are everywhere now, but there is still a lot of confusion among consumers and retailers alike about what “rocker” and its related terms actually mean.

Time for some clear definitions.

But to gain more than an overly simplistic grasp of what rocker is and how it affects the overall performance of a ski, you’ll want to know some other related terms, since rocker design doesn’t function in isolation from—but rather in concert with—all of the other aspects of a ski. So we’re going to need to get clear about some of the other fundamental components of a ski, too. Paging Marshal Olson….

Marshal Olson, Will Brown, and I have had a rather epic and utterly geeked out back-and-forth about this stuff for a while now. Hope you enjoy:

ROCKER 101

Most skis on the market today are, in some way or another, a “rockered” ski. Rocker is no longer just a feature of elaborate powder ski shapes (as it was initially), and even modern world cup race skis (especially the speed event skis), feature some aspect of rocker in their design. So since you’re going to have a tough time avoiding rocker, there’s a whole lot of incentive for you to understand it.

The following list of terms covers the key aspects you’ll need to know to assess and understand the components of a modern ski. We’ll start with the fundamentals.

 

Camber:

Traditional camber is found (unsurprisingly) on traditional skis. When you hold two skis base-to-base, the skis touch at the widest point of the tip and the tail, and there is a gap underfoot. A traditional ski will have the largest gap directly at the mid-sole of the boot.

Traditional camber profile of MOMENT’s Reno Jib

When you compress the camber of the skis by hand, a well-crafted pair will close evenly, creating a smooth, straight, and consistent line of running contact between the edges of each ski. A poorly pressed pair will have small but visible gaps at certain points along the running line of contact between the two skis’ edges.

 

Reverse Camber:

This term was coined in 2001 by Shane McConkey, in reference to the Volant Spatula, a ski he designed with then Volant engineer Peter Turner. The ski had a smooth-radius arc from tip to tail, but in the exact opposite (or “reversed”) direction of traditionally cambered skis.

 

Sidecut and Turn Radius:

For a traditionally shaped ski, the ski is widest in the tip, slightly skinnier in the tail, and narrowest at the waist. These three points are generally connected by a smooth, round radius that defines how the ski carves on edge, and determines how large or small of an arc that ski will carve when skied on edge – which, in simple terms, is called the turn radius of a ski, and this turn radius is defined by the sidecut dimensions.

Sidecut and Turn Radius are actually fairly complex subjects. In the interest of not turning this into a 2000 word digression, we won’t jump down that rabbit hole. But for now, let’s talk about reverse sidecut.

 

Reverse Sidecut:

Reverse sidecut Praxis Powderboards

In addition to featuring reverse camber, the Volant Spatula also featured Reverse Sidecut, meaning that the widest section of the ski is at the waist, and the tips and tails are the narrowest points.

The Spatula has spawned a small sub-set of soft snow skis that feature both full reverse camber AND reverse sidecut. Such skis are referred to as “reverse/reverse,” or R/R for short.

Reverse Camber has also been applied to traditional sidecut skis, such as the 4FRNT Renegade.

 

Rocker:

At the simplest level, “Rocker” means that the shovel rises before the sidecut reaches the widest point of the shovel or tail.

Rockered tip profile of the MOMENT PB&J

The term “rocker” was first used with respect to skis in 2002 by DPS Skis founder, Stephan Drake, in an article published in Powder Magazine. He used the word “rocker” in reference to a new ski he had designed, called the Tabla Rasa.

http://www.rasc.ru/gear/excl/db-tabla-rasa.jpg

The term was borrowed from boat, surfboard, and shoe design (e.g., rockered hull, rockered sole) and is now a catch-all term that now applies to nearly all modern skis to some degree.

The Tabla Rasa had shovel rocker only, complemented by camber underfoot and a flat tail.

Armada, K2, and Stephan Drake’s DPS skis all independently developed fully rockered (i.e., both tip and tail rocker) skis that also incorporated traditional sidecut (as opposed to the reverse sidecut Volant Spatula.)

The DPS Lotus 138 came to market in the winter of 2005/06, and the K2 Pontoon and the Armada ARG were released in the fall of 2006.

DPS Lotus 138

8 Comments

  1. Powder Trout October 2, 2011 Reply

    Great article for people unfamiliar with the various rocker profiles. You mention that WC speed event skis feature rocker. Could you provide an example?

  2. Hey, Powder Trout, sure. Marshal offered these examples:

    First, just FYI, there are no rules against rocker by the FIS.
    Reading FIS specifications:

    1.2.1.5 Camber – No limitations
    1.2.1.8 Running surface – No limitations
    1.2.1.9 Running Groove -No limitations

    Re: specific examples:

    2008 stockli super g skis
    http://cdn.epicski.com/7/73/733c1c4b_IMG_7130.JPG

    Dynastar Speed Course WC:
    http://cdn.epicski.com/c/cf/cf0266b4_dynastar-rocker.jpg

    And the 2011/12 Rossignol Radical WC GS. Rossi’s press release reads:
    “This innovative World Cup GS ski boasts an early rise tip which eases turn initiation, allowing skiers to take more aggressive lines and clock faster times.”

  3. Brendan Sheehan December 5, 2012 Reply

    Hey thanks so much for the article. I just discovered your website and it’s awesome!

    I am wondering if you could tell me how increasing or decreasing the splay of a ski, as well as how changing the rocker line of a ski, changes it’s performance in powder, chopped up crud and hard pack. If I am looking for a one quiver ski, what is a good splay/rocker line profile? I ski mostly in BC powder/crud.

    Thanks

  4. Scott January 5, 2013 Reply

    Question:

    I am 57, former racer, ski Mad River Glen VT, Tight trees, steep and not steep, lots of freeze thaw and pow, medium speed and my strength is not what it used to be. I am looking for a ski to encourage me ski more pow and still be able to get speed on the groomers. I was told the Cham 107 was the answer, but I am not so sure after reading your review. Can you point me towards a couple of options that you like?
    Thanks,
    S

    • Hi, Scott – while it would probably be good to demo the Cham 107 if you get the opportunity, a few other skis that might be worth a look: DPS Wailer 99, SkiLogik Howitzer (review coming soon), DPS Wailer 112RP, and Armada TST.

  5. Blister Member
    Vince Carbone January 21, 2013 Reply

    Great article. When I was looking at new skis got lots of advice on sizing. One thing that made me feel ok about going longer was measuring the run length of my 165cm Line Prophet 100’s which is 140cm. I ended up with 177cm Cochise which I measured at about 138cm. The amount of rocker on the Cohise is deceptive, having read this article I can now use my words:). It has a long rocker line and short splay. So looking at it compared to skis with lots of splay it doesn’t look like it has a lot of rocker.

  6. Blister Member
    SteveH January 29, 2017 Reply

    Great article. I’d love to see a similar article written (or this article updated) to discuss taper and compare/contrast it with rocker.

  7. GuyAnderson March 13, 2017 Reply

    Great articles to refer back to : especially for different ski shapes . J Skis includes the EXACT rocker height and how far pulled back measuring height also.

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