Traditional shape with rocker design question

[vinman]

I'd to discuss design points for s a ski with traditional hourglass shape but with tip rocker.

I have a good handle on designing a 5 dimension ski, placing the base to the tip rocker at the widest part of the ski. This design works well and makes sense to me.

But what I'm having a little trouble with is where to place the base of the rocker on a traditionally shaped ski.

What I've thought about so far is just extending the tip to say 25 cm and ending the rocker there. Making it a 25 cm rocker on a traditional shape in snocad. Is this what everyone else is doing with this type of design?

Or do you allow the rocker to end further back at a spot that is not the widest spot on the ski such as with a ski like the Katana?

Is there even a wrong answer?

[Huck Pitueee]

I just checked a Voile Mojo rx snowboard and the tip rocker extends into the side cut by about 5 inches.

[vinman]

Yeah, I've been doing more research on this and I seem like they are extending the rocker well into the sidecut. Ie. mantra, sir Francis bacon and more.

I guess I need to read more.

[doughboyshredder]

There is no right or wrong answer.

[Huck Pitueee]

Seems like that design wouldn't hold an edge as well as the standard designs but less likely to catch an edge.

[falls]

It also comes down to the shape of your rocker profile too.
If you have an aggressive up curve in the rocker then extension of the sidecut into the rocker is unlikley to allow much of this sidecut to engage when you put the ski on edge on hardpack. However if your rocker rises very slowly then when you put the ski on edge the sidecut will still engage in the turn.
Doughboy is right. There is no right or wrong answer, just skis that feel different to ski.

http://lineskis.com/skis/mr-pollards-opus
Listen to Eric describe his design in the video on this page.
His skis have gone all the way to extreme rocker and now he has come back a bit.
His designs are like your 5 dimension skis, but with a less aggressive rocker profile, a longer sidecut that extends into the low rocker profile and can engage the sidecut still on hardpack, but still with tapered tail and tip - just not as tapered as the standard 5 dimension ski (eg. JJ, S7, some of your designs)

That pollards opus page has some other videos about the design
Here is one about having a longer sidecut in a rockered ski
http://www.youtube.com/watch?feature=pl ... FEi5H3jBKQ

He is right that it makes a better all around ski.
I have a pair that are much like his ski that I made. They are 115 waist but I skied them every day last season in mostly ice/groomers/slush conditions and they worked well. I then skied them in 2 weeks of pow in Japan and they were great there too. However, I think I prefered my 5 dim ski with a more tapered tip and tail in powder, but definitely preferred the longer sidecut ski out ofthe powder.

[Dr. Delam]

In my testing of probably close to a 100 different skis in the last five years I have come to the conclusion that so many theories work. There really aren't any rules anymore.

It all depends on what you are trying to achieve and it takes some experimentation. Or you can simply design something close to a retail ski that you like. I just know that the longer and higher rocker I make results in a looser, more slidable ski. The more I taper the tips and tails lowers the swingweight and further contributes to this effect as well as reducing hookiness. The amount of camber underfoot is also a big part of the equation.

I do have a theory that when skiing in certain types of snow such as denser powder and windblown where the snow is considered more three dimensional, sidecut gets more complicated. If you have a long, more pronounced tip rocker I feel that the sidecut actually changes in this area, when the ski is on edge. If you took a totally straight ski in denser snow, gave it full reverse camber, tilted it 45 degrees on edge, it will carve due to the arc of the reverse camber. I found this out when I first skied some Spatulas.

In the Sierras we get denser wind affected snow a lot where this is noticeable. That is why I have designed most of my skis with the sidecut changing at the point of tip rocker to prevent hookiness.

I plan on doing my next design in 3D to take a look at different views when the ski is on edge. I just need to figure out how to draw in 3D. Anyone else been designing in 3D?

[barnboy]

I'll echo falls... I too spent the bulk of this past season on a traditionally shaped, tip and tail rocketed ski. About 110 underfoot, with a radius right around 20M. They were my goto skis all year, (mostly hard-pack, groom, ice, etc...) and were hands down the favorite demo pair too.

The tip rocker is in the 27cm range, with about 20cm in the tail.

[vinman]

Some good info in here, thanks. 25-30 cm was what I was thinking about for this pair. The guy these would be for has never skis rocker or fat skis. I think I'll put a low rocker on them and run it back behind the based the traditional tip a bit. I'll also put a very small tail rocker in of less than 25 cm and see how this looks. It will so have a fairly long radius with 4 mm of camber under foot. Waist dimension will be 98-100mm.

I like this topic keep the info coming.

[Huck Pitueee]

In my testing of probably close to a 100 different skis in the last five years I have come to the conclusion that so many theories work. There really aren't any rules anymore.

It all depends on what you are trying to achieve and it takes some experimentation. Or you can simply design something close to a retail ski that you like. I just know that the longer and higher rocker I make results in a looser, more slidable ski. The more I taper the tips and tails lowers the swingweight and further contributes to this effect as well as reducing hookiness. The amount of camber underfoot is also a big part of the equation.

I do have a theory that when skiing in certain types of snow such as denser powder and windblown where the snow is considered more three dimensional, sidecut gets more complicated. If you have a long, more pronounced tip rocker I feel that the sidecut actually changes in this area, when the ski is on edge. If you took a totally straight ski in denser snow, gave it full reverse camber, tilted it 45 degrees on edge, it will carve due to the arc of the reverse camber. I found this out when I first skied some Spatulas.

In the Sierras we get denser wind affected snow a lot where this is noticeable. That is why I have designed most of my skis with the sidecut changing at the point of tip rocker to prevent hookiness.

I plan on doing my next design in 3D to take a look at different views when the ski is on edge. I just need to figure out how to draw in 3D. Anyone else been designing in 3D?

The hard part is guessing how much the ski is flexing when its on edge.

[Dr. Delam]

And figuring how much the ski is angled to the snow surface. Infinite variables that I am thinking too much about.

[vinman]

After watching the pollard video, I might have to rethink my approach to this type of ski. I think my tip profile might be too much rise for that type of ski. I may just stick with a 5 dimension ski for this guys and just make the tip rocker shorter and narrow up the waist.

Armada make a 4 dimension ski, the TST. It is basically a 5 dimension ski with rocker/reverse side cut tip, sidecut under the foot, a pin tail, no tail rocker and no reverse side cut othe tail.

This is an interesting design to me and my molds would fit inks design better.

[Huck Pitueee]

It's truly a black art. WoooooOOOOooo.