Waist Width vs Rocker

[Dangur]

Sorry if this has been asked before, but my 20s of TGR search function and Google have not satisfied my curiosity, so-

Which aspect of ski design/geometry makes a bigger contribution to a ski's ability to ski well in powder: Waist Width, or Rocker?

"Ski Well in powder" is a squishy, subjective term, but here's generally what I'm thinking it means: the ski floats sufficiently, is easy enough to control - stop, turn, etc., and is generally fun to ski. There's probably more to it, and my definition is also squishy, but you get what I'm going for.


A little background as to why I'm asking this question: My in-bounds pow skis are old Obsetheds - shitload of rocker (but not 100%), and 117mm underfoot. Last season I picked up Atomic Backland 102s for touring. They are a lot narrower, but have a healthy dose of rocker, and they ski almost as well as the Obsetheds in pow. Now I wonder how skinny I could go, and still have fun in fresh snow, IF the skis were decently rockered. I'm thinking like a 90mm or less underfoot, 20% tip / 10% tail rockered ski could be a buttload of fun, particularly for touring purposes.

Thoughts? Stupid question?

[Supermoon]

I think the answer is both or neither.

So many factors go into how a board rides in powder that you can't really make a blanket statement like that. Shape, rocker, flex, mount point, width, taper, snow type, rider size, etc all matter.

Or just go with the red ones and you'll be all set.

[brundo]

Hopefully doesn't end up being a huge thread drift, but what are some medium underfoot skis with large rocker?

[thefortrees]

Not really possible to answer this. If you like the Backland 102, and want to try skinnier, why not try the Backland 95, 85, or 78? The 78s are red, so that'd be my first choice if you want to ski faster.

https://shop.atomic.com/en/men/touring/touring-ski.html

[lemonhead]

I think the answer is both or neither.

So many factors go into how a board rides in powder that you can't really make a blanket statement like that. Shape, rocker, flex, mount point, width, taper, snow type, rider size, etc all matter.

Or just go with the red ones and you'll be all set.

This

[ak_powder_monkey]

I think tail shape is what makes those backland 102s shine.

But your question is like asking what ingredient makes for a more drinkable beer. So many factors are in play that it's impossible to answer.

[mntlion]

I've used the hoji for years as a pow ski, 195cm with 112mm (interesting fact: rocker shape, matches sidecut)

also have loved the elan boomerage, in a smaller size, for touring (180cm with 120mm)


I just got on the black crows deamon (188cm 99mm) and its also a rockered shape and skis VERY similar to the others above.

same loose, steerable feel.



not sure if this helps.

[Tailwind]

There are two things I think about...

Float = surface area
Lift = how the ski planes up at speed.

Pin tail skis have less surface area than a twin... but have more lift because the tail sinks.

Other ski shapes can create a lot more ‘lift’ outside of pin tails and swallow tails. Mount point for examples is a big deal.

Skis with a lot of lift tend to be much slower... but better for low speed skiing.

The snow you are in makes a big difference.

So a good powder ski for trees (Line Pescado) can be very different than a good powder ski for open terrain (On3P Wrenegade).

[beece]

There are two things I think about...

Float = surface area
Lift = how the ski planes up at speed.

Pin tail skis have less surface area than a twin... but have more lift because the tail sinks.

Other ski shapes can create a lot more ‘lift’ outside of pin tails and swallow tails. Mount point for examples is a big deal.

Skis with a lot of lift tend to be much slower... but better for low speed skiing.

The snow you are in makes a big difference.

So a good powder ski for trees (Line Pescado) can be very different than a good powder ski for open terrain (On3P Wrenegade).

This.

Plus think about how you ski. If you ski fast the waist width matters less because you are driving the shovels into the snow and levitating. Just as an example.

[swissiphic]

The snow you are in makes a big difference.

Truth.

Ski toured and heli skied a number of seasons on custom tip rockered, 190cm Volant Ti Chubbs (88mm waist?) IIRC, we had some classic coastal seasons back then with pretty consistent snowfalls, warmish snowpacks and mostly right side up pow/snowpack structure. With a few exceptions, no matter how deep it got, those suckers floated just fine. Best crud, crust and mash powtato crushers I've yet to ski. Personal ski style has changed and sure do appreciate the loose, slarvey and pivoty turns on present really fat skis but that era was completely satisfactorily soul quenching on the 'skinnies'.

[XXX-er]

I had demo bindings on wailer 112's so I could try lots of mounting points, I found moving the binding back made the ski feel like a boat that wouldn't get up on a plane, IME mounting back of center was not something I liked

[Supermoon]

Too far back and you just plow through the snow. I don’t think mounting back is necessary on modern shapes

[DumbIdeasOnly]

Really it’s both as far as I can tell. I’m not sure one does more or less of the work.

It is also true that for a given amount of float how much you weigh is very important. I have never gotten real float out of skis around 100 underfoot, but I’m a fat assed big dude.

[Tailwind]

Skis like the wailers have a lot of ‘lift’ at the line... further back sinks the tails more than needed and makes them extra slow. The tips might be up but your weight is still way down in the snow and the shovel folds up.

I had demo bindings on wailer 112's so I could try lots of mounting points, I found moving the binding back made the ski feel like a boat that wouldn't get up on a plane, IME mounting back of center was not something I liked

Too far back and you just plow through the snow. I don’t think mounting back is necessary on modern shapes

[I've seen black diamonds!]

Width matters more in low angle terrain.

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[Supermoon]

Width matters more in low angle terrain.

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That's what she said

[Reformed]

Width matters more in low angle terrain.

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I think rocker and flex matter more than width within reason. Cochise provides a good example of this. Shit float for the waist width. I also think the original question is kinda dumb. It needs to snow!

[ready2tumble]

I think rocker and flex matter more than width within reason. Cochise provides a good example of this. Shit float for the waist width. I also think the original question is kinda dumb. It needs to snow!

Can't answer the general question, but can confirm that those Backlands work in powder. Not sure if it's the shape, rocker, flex, or that boat-hull nose, but the 95 has been mysteriously great-turning in some really deep snow.

[sf]

Agree with those who say it's neither/both+taper/flex etc, but consider this:
What floats best of these extremes?
- 130mm traditional cambered ski?
- 90mm heavily rockered ski?

I'd go 130mm/trad if float was the only consideration

[abraham]

Ha Comis floated even with the ridiculous camber. But they weren't the end of the pow ski design evolution

[reckless toboggan]

Praxis Rx?

Hahaha. I kid.

The only corect answer is 4frnt EHP.

You can paint them red if you want to, but you don't have to.

[whyturn]

Pintail with massive rocker like megawatt is big float. Also pontoons.

But full rocker minor side cut is also a winner like kusala or redeemer

Protest is same but camber.

So basically shape and then how much you weigh. Also low angle or tight trees


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[Dangur]

Agree with those who say it's neither/both+taper/flex etc, but consider this:
What floats best of these extremes?
- 130mm traditional cambered ski?
- 90mm heavily rockered ski?

I'd go 130mm/trad if float was the only consideration

This is a great way to simplify my original question. I'd probably go with the 90mm rockered ski...

I understand that waist width and rocker are just 2 variables in ski construction. If you consider all variables, it's a very high-dimensional space to explore. But, in principle, you could slice that space along the waist-width / rocker plane, and visualize their relationship on a surface plot. (i.e., isolate those two variables). It's a reasonable thing to wonder about. In practice, however, it's probably impossible to quantify "ski well in powder." So, like lots of threads here on TGR, we're just wankin'.

[Reformed]

This is a great way to point out the difficulty of my original question. I'd probably go with the 90mm rockered ski... In practice, we're just wankin'.

^ edited for clarity/reality. Continuing the wank, I'll add change for my previous 2 cents. Comparison of extremes doesn't make any sense. Of course a traditionally cambered 130 underfoot ski is going to float better than a rockered 90 underfoot ski - it has almost double the surface area. If we avoid DH race board to snowblade type comparisons I stand by my previous post which suggests that rocker profile and flex play a bigger role in float than waist width for a given ski. Evidence lies in the realization that people had when they bent one of their old fully cambered metal skis. The bent ski was a little easier to ski, floated better and made skiing pow more fun. Matching profiles started being bent into non-bent skis in basements and garages everywhere. It's kinda too bad that uber fat skis were produced/ adopted before bent skis. We ended up skiing some overly wide skis that didn't float all that well. Praise be the modern bent ski!
Edited to add that there is likely a line somewhere where waist width trumps other variables, but it's somewhere out in snowboard territory, so it's not really worth thinking about. 140 underfoot skis obviously float. Would rockered 140 underfoot skis float better? Who wants to ski on 140 underfoot skis?

[SoooL]

Just to add to the above wisdom.

Float is just not float. Meaning; float being the way to keep from sinking in pow going downhill in a straight line is one thing. Float as in being able to manoeuvre skis in repeated turns in pow without stalling, thus losing speed and sinking is another. In the former, waist width might have a bigger contribution, but in the latter, I'd say that rocker profile and flex plays a bigger role.