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

 

Early Rise:

This term was coined by Eric Pollard in 2004 to describe the Prophet 130 that he designed for Line Skis.

“Early Rise” is an alternate term for “Rocker,” and holds the same meaning. People sometimes use the terms as if they signify distinctions, and in practice, people will sometimes use “early rise” to signify a relatively subtle amount of rocker, or more specifically, they’ll use “early rise” when talking about a ski that has a subtle or small amount of “Splay.”

 

Splay:

“Splay” refers to one of two numbers used to give the exact dimensions of any ski’s rocker profile. There is not an industry standard at this point, but most commonly, the splay is measured at the end of the tip and tail. Splay is the height or total amount of rise (usually measured in mm) the rocker has over the snow surface. For example, in the above camber profile diagram of the ON3P Pillowfight, the ski’s tip rocker has 75mm of splay.

ROCKER 101: A Brief History of Rocker + A Glossary of Terms, BLISTER
Diagram of ON3P’s Pillowfight featuring tip and tail rocker and flat underfoot.

To complete the dimensions of a rocker profile, the depth of a ski’s “rockerline” must be taken into account, and to find a ski’s rockerline, we’ll need to establish the “contact points” of a ski.

 

Contact Point:

A ski’s contact points are used to locate the Rocker Lines of a ski. If a pair of skis is held base to base, and is not de-cambered (i.e., is NOT pressed flat, waist to waist), you can easily find the contact points. (See Völkl diagram with marked contact points below.)

The distance from the tip or tail of the ski to these contact points defines the depth of its the rocker line.

Paired with a splay measurement of 25mm, for example, a rockerline measurement of 300mm means that a ski’s tip or tail rises a total of 25mm over a distance of 300mm. Paired together, the complete dimensions would read: 300/25.

Many companies (K2, Salomon, MOMENT, ON3P) list these measurements in a ski’s specs.

Both the rockerline depth and splay measurements of a ski’s camber profile play a significant role in determining its performance characteristics (especially when it comes to running length), and should always be taken into consideration.

ROCKER 101: A Brief History of Rocker + A Glossary of Terms, BLISTER
Völkl’s diagram of their tip and tail rocker profile with Contact Points marked in red

 

Running Length:

This measurement is used to find the distance between the contact point of the shovel to the contact point of the tail, and will tell you how functionally “long” the ski is (i.e., how much of the ski is actually in contact with the snow when skied bases flat).

The Running Length measurement allows you to easily compare lengths between models that have varying amounts of rocker, since a heavily rockered 190cm ski will feel more similar on firm snow to a less dramatically rockered 184cm ski.

For now, we’re going to leave things there. Hopefully this helps to clarify some of the relevant ideas and terms surrounding this whole rocker thing, and we’ll pick up on these themes soon with a more in-depth article on ski shaping and design.

10 comments on “ROCKER 101: A Brief History of Rocker + A Glossary of Terms”

  1. 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. 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. 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

  5. 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. 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. 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.

  8. Jonathan,
    Do you think it would be appropriate to add the definition of “early rise” into this discussion? I hear people all the time calling this rocker. Am I mistaken here or is this something else? Just for laughs, in the old days we referred to early rise as a bent ski! It actually skis that way too!

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