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Wide skis and edge angles

post #1 of 21
Thread Starter 
In the Real Skiers forum an interesting discussion surfaced from two statements made by Peter Keelty. They were:

1. Wider skis respond more slowly and the wider the ski, the more slowly it responds.

2. Moreover, the wider the ski, the faster the skier must go to obtain the same edge angle.

My personal observations are that the difference in response time between narrower and wider skis decreases as speed is increased. Also, beyond a certain speed of about 25-30 mph, I can attain the same edge angle regardless of the width of the ski.

What are your observations?
post #2 of 21
This is almost the same as a thread I was thinking of starting. The problem with the above - and some of the ideologically driven statements on that other forum - is that it is subjective. I confess my math is a bit stale for it, but I'm sort of hoping that someone like PM could compute some objective estimates for force required and time to rotate to something like 45 degrees for a family of skis ranging from 70mm to 110 mm. I suspect it'd take a couple different calculations for different snow conditions - since on hardpack you are lifting the ski onto edge, where in contrast on soft enough snow you are almost tilting it on an arc with the center point being the center line of the ski - so the differences could vary greatly depending on snow type. Still, it'd be interesting to know if that difference in getting on edge (say from flat to that 45 degrees) is typically milliseconds or seconds - or where in between.

Subjectively speaking - for the skiing I do, I usually don't find the transition time differences that material compared to the benefits I seem to get from a fatter ski. The sole exception is a really fat (110+) & soft ski on crust/hardpack. Then it is tough to get on edge and the hookup is hard to control when it happens (tight radius sidecut). My answer is embarassing side slipping when I hit the combination of those skis and snow conditions . The designer's answer boiled down to: don't take them out on days when those conditions prevail . Seriously though, at least where I live - and for the skiing I do - I can say that I usually don't notice the edge transition thing that much. And I do notice the float and control benefits a great deal.
post #3 of 21

I think the bigger thing is the effort required

While it's true that physics says that the time will be slightly slower, I think the real issue is the extra effort required to get the ski on that 45 degree edge angle. Think of a crowbar with a 2 foot handle and 6" prying end. Try to imagine working with that that same crowbar with a 2 foot handle but with the prying end 18" long.

"spindrift" is correct that it is worse on harder snow because the distance from the edge of the ski to the fulcrum (somewhere under the foot or big toe) is greater, but the diffrence still exists even on soft snow. However, I believe that it affects beginning to intermediate skiers still learning to get the skis up on edge MUCH MORE than more experienced skiers who already have the muscle memory and technique to edge.

It do find it interesting that I have read multiple posts here and on RealSkiers from people commenting about how their technique degrades if they ski "lots" (whatever that might be) on wide skis and they need time back on the slalom footprint to polish movements and get "back in touch with their edges."
post #4 of 21
Lever Arm = Leg Length. A major factor in this 'equation'.
post #5 of 21
Quote:
Originally Posted by gandalf View Post
While it's true that physics says that the time will be slightly slower, I think the real issue is the extra effort required to get the ski on that 45 degree edge angle.
Time and the force driving acceleration are not exactly unrelated here... Unless the forces we generate with our legs (assuming proper position) are so great relative to getting the skis down/up that the skis accelerate almost instantly to some semi-constant velocity - and then stop "instantly" as well. I'm not sure this is a reasonable simplification -but hey, this is the kind of stuff that makes me hope some practicing engineering/math heads will jump in...
post #6 of 21
Trying to slap a slide rule on this is equivelant to quantifying ski performance in deep snow by width alone. Neither will (alone) deliver a valid answer. I ski about 50-70 different skis every year (and I own two skis in the 95-100mm range) I am not anti-fat skis but they have serious limitations for some skiers.

When testing, if I ski the way I normally might, Ie: fairly fast and with a high edge, fat skis are great. OTH, when I test skis for turn shape versatility, ease of transition from short turns to long turns, and manuverability in bumps, fat skis are ponderous.

Over years as a ski rep and now later in life as a retailer again, I have handed skis to many hundreds of skiers, sent them out on the hill and often watched them come down. I have usually been able to interview them at the end. The average skier is probably a level 6.4227534 (give or take) and says they are a good intermediate/low advanced skier. The fact is that many of them can't buy a high edge angle with a BIG bag of quarters.

These skiers struggle when they are on skis that are too wide. They can't find an edge, apply edge and pressure progressively, and they have trouble maintaining pressure though the turn. Most folks of this description have to resort to muscle to get really wide skis around. Naturally the threshold of too wide varies from skier to skier.

I could ski on a 90-100mm ski every day, but choose not to because they are often a bore. More importantly, most skiers are not me and they are also not the big mountain types that endlessly promote wide skis because that is what they ski on and like.

This is not new news and I am not the first to come to this conclusion.

SJ
post #7 of 21
It is true that it takes more effort to put a wider ski up on a high angle, but I don't think that the main problem that led to the comments reffered to in the first post. The main thing is the these wide skis are also typically long radius skis, designed to make longer turns. In order to make longer turns and experience the same g-force in the turn (like feeling pressed into the car door) you have to be going faster.

Acceleration is V^2/R choosing numbers to simplify the math, a 40 m radius turn requires twice the speed as a 10 m radius turn to get the same g-force. The ski is designed to make a bigger turn while bending less with the same force applied to it. Imagine that you want to make small turns with a long radius ski. If you want to make a smaller turn you have to apply more force to it, and you have to tip it to a bigger angle. If you like making 2-g turns with your slalom skis and want to make the same turns with the LR skis, it probably ain't gonna happen; you would need to go faster and pull 4-gs.

BTW. I had heard disdain for people who make small turns from those who make long turns, but I didn't know it went both ways. I like all turns; in my book, it's all good.
post #8 of 21
Jim, I sure can't argue with you about what you are observing. I see a fair bit of the same as I study folks on the slopes. However, I think this drifts out of the equipment realm into a broader discussion of technique and instruction. I'm not at all sure that learning to put a modern "fat" ski on edge is all that hard. I think it just as likely that many of the intermediates and beginners you describe have simply never been taught to ski on two feet with two edges (under any conditions). Or two planing surfaces...

Once a modern oriented instructor showed me how to ski two footed, my biggest challenge was unlearning a bunch of what I'd learned the previous 3 years. And I'm still working on some of it. On the other hand, watch kids going out with their skilled buddies & they get a handle on this - often very quickly. Maybe the issue is less fat skis and more the poor quality (or limited quiver) of instruction available to the average beginner?

But back to the topic - I do think you can put the edge to edge debate to rest for the 90% case if someone does the math... That won't make one ski type better than another - but it will make the trade offs more objectively debatable. The related technique issue is another discussion.
post #9 of 21
Quote:
Originally Posted by Ghost View Post
The main thing is the these wide skis are also typically long radius skis, designed to make longer turns.
My 113 waisted Crystal Ships have something like a 12 meter radius
post #10 of 21
The exception proves the rule;my SGs have about a 68 mm waist and are almost straight.
post #11 of 21
I don't understand why this is an issue. They aren't designed to perform particularly well on hardpack. They're designed for soft snow. You don't need a turning radius of ANY shape simply because the sidecut of the ski is not making the turn in soft snow, and so you dont need extreme edge angles. Want a smaller turn? Buy a softer ski, which wil bend more when it comes into contact with soft snow. This is why small radius fat skis are about as useful as skiboards.

If you really want performance on hardpack, you buy a carving ski.
post #12 of 21
Quote:
Originally Posted by Takecontrol618 View Post
I don't understand why this is an issue. They aren't designed to perform particularly well on hardpack. They're designed for soft snow. You don't need a turning radius of ANY shape simply because the sidecut of the ski is not making the turn in soft snow, and so you dont need extreme edge angles. Want a smaller turn? Buy a softer ski, which wil bend more when it comes into contact with soft snow. This is why small radius fat skis are about as useful as skiboards.

If you really want performance on hardpack, you buy a carving ski.
Obviously, in a ideal world, we would each have a different ski for every imaginable condition, terrain and turn shape out there, but most people I know are looking for something a bit more versatile. I know very few people who make their way to the bottom of the bowl, ditch their Pontoons and have a pair of carving skis waiting for them.
post #13 of 21
I know very few people who use pontoons and give a damn how they perform on hardpack.

If you buy a pair of fat skis, and your biggest quarrel with them is that they're sluggish on groomed runs, you got the right skis. On the other hand, if you buy a pair of fat skis, and you're disappointed that they dont perform well on the groomed, you're an idiot.
post #14 of 21
Quote:
Originally Posted by SierraJim View Post
Trying to slap a slide rule on this is equivelant to quantifying ski performance in deep snow by width alone. Neither will (alone) deliver a valid answer. I ski about 50-70 different skis every year (and I own two skis in the 95-100mm range) I am not anti-fat skis but they have serious limitations for some skiers.

When testing, if I ski the way I normally might, Ie: fairly fast and with a high edge, fat skis are great. OTH, when I test skis for turn shape versatility, ease of transition from short turns to long turns, and manuverability in bumps, fat skis are ponderous.

Over years as a ski rep and now later in life as a retailer again, I have handed skis to many hundreds of skiers, sent them out on the hill and often watched them come down. I have usually been able to interview them at the end. The average skier is probably a level 6.4227534 (give or take) and says they are a good intermediate/low advanced skier. The fact is that many of them can't buy a high edge angle with a BIG bag of quarters.

These skiers struggle when they are on skis that are too wide. They can't find an edge, apply edge and pressure progressively, and they have trouble maintaining pressure though the turn. Most folks of this description have to resort to muscle to get really wide skis around. Naturally the threshold of too wide varies from skier to skier.

I could ski on a 90-100mm ski every day, but choose not to because they are often a bore. More importantly, most skiers are not me and they are also not the big mountain types that endlessly promote wide skis because that is what they ski on and like.

This is not new news and I am not the first to come to this conclusion.

SJ
First, about me,
I couldn't buy a high edge angle with a big bad of Susan B Anthonys... But, I really don't want to, I like quick turning. I'll go big angle on occasion if I'm riding an edge around a big GS turn, or sometimes when I match the track of a good snowboarder, but for the most part I'm having quick edge to edge fun. It's been more times than I could count, like when I'm in a clinic, or I decide to concentrate on my turns that one of my friends would watch me, then ask, "when the hell did you learn how to ski".
Which brings me back on topic, every 80+ mm waisted ski I've tried, I've been bored silly, they are so sluggish. I also do very good in powder, or east coast cement, with my soft 70 mm waisted ski, but I really do want to get a midfat (to you guys) ski for those situations. Jim, any suggestions on a 80-90 mm waisted ski that I should put on a list to demo?
Off the top of my head, here's some skis I've tried and were OK but I wouldn't buy them...
Fischer AMC76, AMC79
Rossi B2 (yes, the B2 was too sluggish, I'm on B1s)
Blizzard Titans (8.2?)
Solly Pocket Rockets

I did like the Salomon 1080 (not the mogul or the gun or the foil or any other variation, I'm talking the original 1080, yellow, circa 1998-2001?,of which I don't know the waist, but I think it was in the high 70s) Which is why I bought the Salomon 1080 CR Labs, so I hopefully answered my own problem.
post #15 of 21
I think this whole discussion is moot since wide skis are intended for backside conditions and deep snow. They are never going to be the most efficient tool for the job on groomers, but some of them are able to do an admirable job of "getting back to the lift".
post #16 of 21
Quote:
Originally Posted by Noodler View Post
I think this whole discussion is moot since wide skis are intended for backside conditions and deep snow. They are never going to be the most efficient tool for the job on groomers, but some of them are able to do an admirable job of "getting back to the lift".
I believe you are wrong about this. Even for a "frontside" ski (at least in the PNW), I'd be inclined to go relatively wide at this point. In the whole range of conditions I run into, hardpack is not that common except at choke points. On the whole, even on the frontside, I spend more time on soft groomers, overlying soft snow, slush, etc. than I do on true hardpack. So a fatter ski is a fine tool for the majority of what I run into on trail - not to mention that I try to spend as much time as my skills and conditions allow off piste anyway. Still, there are "groomer days"...

I guess I believe that in much of the country, as more and more people learn to ski wider skis, that more and more people will use "fat" skis as their "baseline" ski and will view skinnier skis as a quiver ski for hardpack groomer days. The next five or so years will tell...

Along these lines, it'll be interesting to see what the reactions are to things like the new generation of Icelantic boards (anyone skied the Nomad in a variety of conditions yet?).
post #17 of 21
On hardpack, for a ski of width W edged to an angle Θ we -can- notice some things:

The distance the foot lifts off the ground is proportional to W/2*sin(Θ).
Notice that the work required to get that last little dΘ goes as sin(Θ), the greater the Θ the harder it is, and that W/2 acts as a further gain-multiplier.

What does that mean? Let us compute the work a skier of mass m does for three different angles and with three different skis. This ignores the work put into decamber of the ski tip & tail.

66mm ski - 5 deg: mg*2.88mm 10 deg: mg*5.73mm 40 deg: mg*21.21mm
88mm ski - 5 deg: mg*3.84mm 10 deg: mg*7.64mm 40 deg: mg*28.28mm
100mm ski - 5 deg: mg*4.36mm 10 deg: mg*8.68mm 40 deg: mg*32.14mm

The difference in work required to get a 100 mm ski to 40 degress vs a 66mm ski to 40 degrees is larger than the work required to get the 100mm ski to 10 degrees.

We can spray about leg length, plates, sidecut, speed, centrifugal force, etc. but all of that merely tells us
a) how much force a skier puts in over what distance to get to a certain edge angle (the total work is the same either way) and
b) what the ski does to turn at that edge angle.
post #18 of 21
2-turn:

There are some pretty good skis on that list of "okays" To improve quickness, I think you want to look outside the simple parameters of width and go more for the "personality" of the ski. My read on this is that you will like a lighter feeling ski with some good snap. Also keep in mind that as you go wider you can go shorter if you choose to.

So...........

80mm...................Legend 8K (same dimensions as the AMC-79 but more snap)
85mm...................Solly WX Fury
88mm...................Snoooooop

SJ
post #19 of 21

Legend 8k

I completely agree with SierraJim on the Legend 8k and on all the previous comments. I have a small quiver of some old Intuitiv 71's, Legend 8k, and Mantras. The Legend 8k is one of my favorite skis of all time for quick turns...easy to get on edge and is very powerful for the relative lightness of the ski. It actually "feels" almost quicker than the old 71's...so much so that I now use those as a rock ski.

Here's praying we have a great season in Tahoe...
post #20 of 21
Quote:
Originally Posted by SierraJim View Post
2-turn:

There are some pretty good skis on that list of "okays" To improve quickness, I think you want to look outside the simple parameters of width and go more for the "personality" of the ski. My read on this is that you will like a lighter feeling ski with some good snap. Also keep in mind that as you go wider you can go shorter if you choose to.

So...........

80mm...................Legend 8K (same dimensions as the AMC-79 but more snap)
85mm...................Solly WX Fury
88mm...................Snoooooop

SJ
Thanks Jim, Neither my regular shop or the mountain shop (where I can get free demos) have Dynastar, but I can try the snoop and the Solly there as soon as the snow flies, hopefully that would be this winter. I'll look for Dynastar at our demo day, but I don't think they participate.
Maybe I'll give them a try on a western trip.
post #21 of 21
Quote:
Originally Posted by 2-turn View Post
...........as soon as the snow flies, hopefully that would be this winter.
Now that last part is scary.........I think I'm gonna make a trek to Mammoth next week.

Two of my employees were seaching the web for last second flights to Co. last night. Dunno how they fared (pun!) but where there's a will, there's a way.

SJ
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