Skiboard Construction - Stiffness/Flex Pattern

[BrklynCarver]

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 stiffness/flex pattern:


Stiffness:
The lengthwise stiffness for a given flex pattern is measured by placing weights at the binding location and measuring the deflection of the board while it is supported horizontally at the tip and tail. It is important to get a board that has the right stiffness based on your weight so that you can decamber it properly when you are in the middle of a turn. Stiffer boards require more weight or harder carves to decamber. If you weigh more, you need a stiffer board. If you intend to carve hard GS turns, you need a stiffer board. There is no standardized measurement for stiffness, and each manufacturer has a different metric.

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Flex Pattern:
A single stiffness metric for a board is somewhat misleading, because it does not take into account the flex pattern. The flex pattern determines how the board decambers in a carve. Some boards may have a non-linear flex, depending on the materials used: the board flexes rather easily, then suddenly becomes very stiff past a certain decambered radius. If a board manufacturer specifies stiffness indexes, it's best to treat those values as relative, for use only in comparing stiffness between boards in the manufacturer's lineup. One other thing to keep in mind: a board becomes slightly less stiff every time you apply a base grind. Flex pattern also partially determines how much energy springs back from a turn to help you hop into the next turn. The flex pattern plays a role in how pressure is transmitted to the edge of the board. If all the pressure gets transmitted to the center of the edge, the board will have bad edge hold on ice. Different flex patterns are optimized for different terrain:

Boards that are stiffer at the nose and tail, but softer between the bindings are better for powder. The stiffer nose provides support to prevent the nose from digging in. The softer mid section will give you more maneuverability through the trees, since it will allow you to shift your weight back and wheelie your way through powder when necessary.

Boards that are softer in the nose and tail, and generally softer throughout, tend to have better edge hold on ice.

[jjue]

The whole issue of stiffness and edge hold with skiboards is fascinating to me and I am still confused about the issue . I initially thought that the stiffer the board the better on ice. . I almost bought the Loken CTB until folks told me that that thing didn't have the greatest edge hold in ice .. yet my very stiff Summit 110 seems to do fine in ice , I guess it has to do with length of effective edge and torsional ridgitiy across the middle of the board rather than over all stiffness . Even a very short wide pretty stiff board like the KTP 101 does very well in ice . I think Kirk mentioned that he felt that you needed to be a certain weight to get that board to flex properly. What happened with the very stiff Summit 110 woodie was interesting in that lighter weight folks couldn't get the board to decamber correctly and tended to slide out .....

[Docta]

Some more notes on flex:

In my view of the world, stiffness (and also surface areas if we were discussing deep snow) is the aspect of ski design that makes skiboards suitable for heavy or light riders, not the length.

Riders need enough stifness so that during a tight carved turn, the ski flexes to the point where the edge is laid flat on the snow and the ski turns perfectly in its described arc. (Lay you boards on the kitchen table at steep angle, then flex them till the edge lays flat and you will see what i mean) If the ski is too stiff, the required force to bend the ski isnt achieved, and the board wont carve. Too flexible, and when pressured the ski either skids, or the (too flexible) tips and tails overflex causing chattering.

Heavy riders, or thse who ride fast and forcefully, need stiffer boards.

Riders also note that bindings setups have critical impacts on the stifness and flex charachteristics of a ski.

[PedroUK]

I agree that heavy riders, or those who ride fast and forcefully, need stiffer boards. I also believe that with a stiffer board it helps to do the 'old school' technique of weighting and un-weighting. In modern ski teaching this is often left out altogether and thought of as unnecessary, even frowned upon, for modern carving skis and the like. Im my view this is a mistake, especially for skiing difficult terrain and advanced turns.

The custom 110 (woodie stiff) is a dream when weighted and un-weighted in a turn but hard work if not. This takes practice but for me (I have been skiing for a long time) it is natural and I do it without thinking. In fact it is harder for me to ride without doing it.

[DennisEvans]

Just for kicks, what would you recomend for me? I am 5'10 and a half and 140lbs I want something with a good amount of flex in the 90-99 range. Should I go with more flex or less, and should I go longer or about that range length wise. Right now I have short skis and am extremely good at catching air and fair at steep ungroomed terain.

[BrklynCarver]

Being 140lbs, you probably want more flex, especially if you are hitting the park. For me, I'm 5'5 and between 170-180lbs, I don't do park, but I am aggressive on the mountain with tons of speed and high speed carves, hence why I prefer a stiffer skiboard, I am able to push all my weight and muscle into a carve and make a stiff skiboard camber properly.

[Manlenium]

Originally posted by jjue
The whole issue of stiffness and edge hold with skiboards is fascinating to me and I am still confused about the issue . I initially thought that the stiffer the board the better on ice. . I almost bought the Loken CTB until folks told me that that thing didn't have the greatest edge hold in ice .. yet my very stiff Summit 110 seems to do fine in ice , I guess it has to do with length of effective edge and torsional ridgitiy across the middle of the board rather than over all stiffness . Even a very short wide pretty stiff board like the KTP 101 does very well in ice . I think Kirk mentioned that he felt that you needed to be a certain weight to get that board to flex properly. What happened with the very stiff Summit 110 woodie was interesting in that lighter weight folks couldn't get the board to decamber correctly and tended to slide out .....

This is interesting to me as well. Being heavier anyways, ive been looking for a board that carves hard, while still staying under the 100 bar. I think a pair of KTPs next season sounds good.... I still like rocks attached to my feet.

Should have bought some lokens when I had the chance!!!! BAHH!!

I did settle on some lacroixs though...

[BrklynCarver]

The Lacroixs are just as stiff as the KTPs, maybe a little stiffer, so you won't be disappointed. They are heavier than BWPs/KTPs, so keep that in mind.

[Manlenium]

I like weight on my feet, dont ask me why. When I first rode Grooves they felt so heavy compared to the R8s. However durabilty was an issue.

[valmorel]

I am going to throw a curve ball here and suggest that required stiffness is also a function of ability. Here is what I mean: it seems that, initially, a softer board might help a beginner get up and into carves more easily. As the rider progresses, a stiffer board helps with higher speed carves BUT, as we go beyond that point, a stiffer board starts to work against the rider by not absorbing the irregularities at higher speeds, and throwing the rider off line and off edge. Thus, an expert rider might actually get more performance out of a medium flex board. This is my experience anyways..........................

[Greco]

Originally posted by valmorel
I am going to throw a curve ball here and suggest that required stiffness is also a function of ability. Here is what I mean: it seems that, initially, a softer board might help a beginner get up and into carves more easily. As the rider progresses, a stiffer board helps with higher speed carves BUT, as we go beyond that point, a stiffer board starts to work against the rider by not absorbing the irregularities at higher speeds, and throwing the rider off line and off edge. Thus, an expert rider might actually get more performance out of a medium flex board. This is my experience anyways..........................

i concur dave, i consider myself an expert and couldn't be happier with the medium flex Revel8's.

g

[valmorel]

Sure thing G. The Revel8s seem to absorb the rough terrain really well which makes really high speed stuff feel more stable. I love dragging my hand on the snow in big high speed carves on hardpack on my ALPs, but have been on stiffer boards where doing this felt a mite sketchy

[valmorel]

BTW, I think I would have found shooting the video for the Three Guys thread just about impossible on a stiff board

[PedroUK]

Originally posted by valmorel
I am going to throw a curve ball here and suggest that required stiffness is also a function of ability. Here is what I mean: it seems that, initially, a softer board might help a beginner get up and into carves more easily. As the rider progresses, a stiffer board helps with higher speed carves BUT, as we go beyond that point, a stiffer board starts to work against the rider by not absorbing the irregularities at higher speeds, and throwing the rider off line and off edge. Thus, an expert rider might actually get more performance out of a medium flex board. This is my experience anyways..........................

Nahhh... I don't agree with this at all and it's certainly not my experience. A softer flex (we are talking longitudinal flex) will be better in powder and better in moguls but if you want to carve hard and fast on piste AND have the experience a stiff board wins hands down everytime. There is a reason for pro downhill racers using some of the stiffest skis ever made. I also find that when a skiboard starts 'absorbing the irregularities at higher speed' it has lost all stability and becomes impossible to control, whatever the experience of the rider.

[PedroUK]

Originally posted by valmorel
Sure thing G. The Revel8s seem to absorb the rough terrain really well which makes really high speed stuff feel more stable. I love dragging my hand on the snow in big high speed carves on hardpack on my ALPs, but have been on stiffer boards where doing this felt a mite sketchy

I find the opposite and have no trouble doing the exact same thing on stiff skiboards. While with softer flex boards doing this feels sketchy.