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Skiboard Construction - Sidecut

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  • @zenboyscout
    replied
    Praise geekdom.

    Leave a comment:


  • bri_guy
    replied
    This thread has changed my life.




    Okay maybe not, but a lot more makes sense to me than it previously did. For one, I didn't know what a carve really was until I read this.

    Leave a comment:


  • xxxander
    replied
    So, its really crazy reading these posts! I am not one to get very technical! but its always fun to read. My first pairs were very short 85cm Journeys with a very deep sidecut depth, and 90cm Line Five-O's with an almost nonexistent sidecut depth.
    I guess being new to the sport and very naive, I had no idea what to expect. However using these two boards interchangeably was interesting, and exactly as posted earlier! The great thing was that I just did it without fighting at all. I turned hard when I had to and turned soft other times.

    The strange thing to me is that now being more experienced (not that much at all btw) It doesn't really matter what board I'm on, its either a hard turn or soft turn. Whether or not the board skitters or carves smoothly I just do it on whatever board i'm on. The biggest difference I feel is the powder! the shorter boards just dont cut it!!! HAHA!

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  • jjue
    replied
    Nice observation oxenboxin,
    Valmorel's points are well taken . .
    what I have found is the very tight turn radius skiboards while super fun and carvy , , kind of fight me a bit when I want to go into longer , more cruising type high speed carves , you can exit the carve sooner and not follow it all the way out and make longer , wider arcs. , , but it does feel that you are fighting the desire of the board to pull you into a tighter arc ,
    on the other hand short skis , say with a turn radius of 15m or so .. do the opposite , they carve better in a wider arc then I want to go on a croweded slope , and so I have to slide the board rather than carve to get back into a tighter turn ..
    for me , primarily oriented to cruising rather than park where tight turns may be the cats meow .. boards that have a bit of wider turn radius like the Spruce boards are very nice and fit my needs to a tee .. not too tight and not to wide .. it really doesn't matter the length of the board .. and I had the same experience with bombing the groomed slopes on the 95cm Line Bullet that has a Spruce like turn radius and was amazing in arcing turns in firm snow .. at speed. .
    I suspect the Rumspringa with its more relaxed turn radius and longer length will be like a Line Bullet on steroids ... and a true delight on firm snow and carve big cruisey type turns like a Ginzu knife...

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  • valmorel
    replied
    Brilliant! I love how you 'get it'! I am sure jjue will want to chime in here too.

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  • oxenboxin
    replied
    Originally posted by valmorel View Post
    All of which brings me very neatly to discussions I have had with jjue and others over the last couple of years, namely, IMHO, skiboard sidecuts have gotten a bit too tight. With these sub 6m radii, it takes more skill than it should to get a good grip on ice, but at the same time, turning generally is not significantly easier. Stability at speed can be a bit challenging, and really tight sidecuts generate more resistance (seen as the rooster tail), and are therefore slower. From personal experience, around 7m seems a nice compromise.
    So, if I get you right, I should be able to get a more confident feeling on ice by cutting tight turns- turns that are as close to the turning radius of my boards as possible. That's really tight! This explains my experience on my Revolts. They felt rock solid and carved absolutely beautifully when I went slower and made tighter turns. At higher speeds I couldn't achieve the same sensation.

    So on my Revolts (580cm radius), if I imagine circles on the slope that are about 12 meters (38 ft) across (i.e. 6m radius) my ideal carving turn would be tracing the edges of those circles? I'm totally going to draw some out on the ground with chalk. I'm a geek like that.

    My excitement for the Rumspringa (with it's larger turning radius) grows, and suddenly I understand why some people are so into the Spruce 120.

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  • valmorel
    replied
    All of which brings me very neatly to discussions I have had with jjue and others over the last couple of years, namely, IMHO, skiboard sidecuts have gotten a bit too tight. With these sub 6m radii, it takes more skill than it should to get a good grip on ice, but at the same time, turning generally is not significantly easier. Stability at speed can be a bit challenging, and really tight sidecuts generate more resistance (seen as the rooster tail), and are therefore slower. From personal experience, around 7m seems a nice compromise.

    Leave a comment:


  • Docta
    replied
    I think jjue is right, some of the info on this one is a bit misleading.

    Its very easy to make wide sweeping turns on a short carving radius ski... the turn feels different from a true carve, but it still turns well, much better than a skidded turn like i will describe below.

    Long carving radius skiis can absolutely turn tighter turns than they are designed for, by skidding throughout most of the turn...

    Everybody, before the shaped ski revolution that began to occur with the advent of the snowboard, made skidded turns at all but the highest speeds... thats the only way to ski an expert slope when youre turning radius in 30meters.

    However, for perfect edge hold and a perfect quiet non-skidded turn, you need to ride the board in the exact turning radius that it has...

    To short a radius, and you can only "carve" short tight turns at low speed, but you can make pretty much any length turn you want by underturning.

    To long a radius, and you have to skid or "overturn" the ski at all but the highest speeds.

    7.5m, like the 120 is too tight for me at all but the slowest speeds, or when carving playful solid arcs on steeper stuff.

    10m, like the hagan, is a real nice compromise... tight enough for tthe steeps and picking good lines, not too big so that it only carves when pushed too hard.

    15m like the scout 143, can only be carved at high speed... and it does this well.

    More than a 15m radius is only needed for high speed gs type runs.

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  • jjue
    replied
    One of the defining characteristics of skiboards is their small side cut radius and shorter effective edge compared to long skis ... one of the things that skiers need to be taught and don't get right away , is that especially with very short skiboards , they need to be making a lot of turns and going edge to edge ,as opposed to the way they ski their long skis which is to let them run straight and ride big arcs .... what amazes me however, given all this how well skiboards can do making big loopy carves at high speed , I can do that almost as well with my Ktp 101 as my Marauder 125 or Sherpa 130 !

    Leave a comment:


  • BrklynCarver
    started a topic Skiboard Construction - Sidecut

    Skiboard Construction - Sidecut

    I started doing some research today into the various materials that goes into a skiboard and found a wealth of information. What started this was comparing the Summit Maurader 125 vs the Lacroix Carbon 125, with the Maurader using p-tex 4000 vs. Lacroix using p-tex 2000. Therefore, I think it could be helpful to start some threads about the materials used.

    This thread is about sidecut:

    Sidecut radius:
    The sidecut radius is the radius of the approximate circle that defines the board's edge when the board is laid flat on the ground. The sidecut radius is a measure of how tightly the board will want to turn.

    Small sidecut radius boards want to make small-radius turns at low speed. If you push them beyond a certain speed, the G-force from the turn will try to push them into making a larger arc, and they won't be able to hold an edge, resulting in a chatter or wash-out. Large sidecut radius boards want to make large radius turns at high speed, and let you cruise big arcs.

    They won't start to carve until you get them up to a certain speed, which means you may need to burn up more terrain when starting down the hill before carving, otherwise you will either tip over or skid out. Smaller sidecut boards are good for crowded slopes where you need to slalom your way around people at lower speed, or for resorts that have narrow runs. Get a large sidecut radius if you want to go fast on a wide run during the weekdays when few people are on the slope.

    The actual radius of a carved turn (the decambered radius) is tighter than the sidecut radius and is a function of the sidecut, how high the board is tilted on edge, the stiffness of the board, and the pressure applied by the rider through the binding. You will get a smaller radius turn with a smaller sidecut, higher board edge angle, softer board, and more binding pressure. However, the dominant effects are different depending on how high the board is tilted on edge:

    If the board is very high on edge, the stiffness of the board and the binding pressure mostly determine the decambered radius.

    If the board is lower on edge, the sidecut radius will primarily determine the decambered radius.

    It is possible to muscle a large-sidecut board into a smaller arc, but you can't force a small-sidecut board into a bigger arc. If you get a large sidecut board, you can "grow into it" as you gain more carving skill, by shortening the decambered radius as you get better.

    What sidecut is better for ice? A smaller sidecut allows you to carve at a lower speed, but you don't get as much effective edge for edge hold. A larger sidecut forces you to carve at higher speeds, but you get more effective edge. The answer is to use the largest sidecut for your skill level: Advanced carvers can muscle a large sidecut radius board into a small decambered turn radius, bleeding off speed, while using the longer effective edge of the bigger board.

    In order to make the board follow a path that is circular when decambered on the snow, the manufacturer often designs the board using a sidecut shape that is not a circle. Which means the sidecut radius changes along the length of the board, using one of several methods:

    Using a mathematical curve: Conic sections, Quadratic, Elliptical, Parabolic, etc. The average radius of the sidecut curve is different at different points on the board, and determines how the nose, tail, and center of the board hook up with the snow.

    Using a progressive sidecut that starts out larger near the nose (to make it easy to enter turns), then changes to a smaller radius near the tail (to provide acceleration, like a slingshot).

    -----------------------

    Sidecut Depth:
    The distance that the sidecut intrudes into the board, measured from a line connecting the widest point at the tip and tail to the deepest point on the sidecut. Greater sidecut depth (smaller sidecut radius on a larger board) results in a board that is more hooky. There is sometimes ambiguity when people use the term "sidecut" without a qualifier, since they could be referring to either sidecut depth or sidecut radius.
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