Ski Length & other questions of mechanics.

Greetings,

A few questions on the basic working of skis.

How does edging create a turn? One ski going flat and straight down
the fall line goes straight. Lean the ski on edge and it turns.

Now downhillers & GSers tend to use long skis. Why is this? Do the
longer skis provide more stability?

Thanks

"Mark A Framness" wrote in message
om...
Greetings,

A few questions on the basic working of skis.

How does edging create a turn? One ski going flat and straight down
the fall line goes straight. Lean the ski on edge and it turns.

Now downhillers & GSers tend to use long skis. Why is this? Do the
longer skis provide more stability?

Thanks

After making a quick assumption about where you must
be experience wise, that being, not much if any?, I would
suggest that you first shoot for getting all over the front
of the ski and causing the tail to skid around the tip of the
ski, which (the ski) , due to the shape of it (big in the tip),
will be only too happy to oblige you and turn. This is the
oldest, most basic way to make a ski turn. It used to work
whether or not there were edges.

This will work if you're using a wedge or parallel stance.

Basically, as you start out as a skier, in my opinion it's
much easier to turn the skis if your weight is mostly on the
front half of the skis. If you are in the "back seat", you'll
have trouble trying to turn the skis. If you can pick up
the tail of the inside ski while leaving the tip on the snow
during the finishing phase of the turn, you are not in the
back seat. The back seat is when your weight is mostly
on the tails of the skis.

Due to the *sidecut* of a ski, as you say, if you simply
lay it on it's edge, it will turn, but if that's all you do,
the turn will be of a fairly large radius. This would
be along the lines of a *carved* (as opposed to skidded)
turn.

To shorten the radius of the turn in a purely carved turn
you must *bend the ski*. You can do this by driving the
knees forward and toward the center of the turn.

You can also help the skis along in their effort to turn
by rotating your entire leg (from the hip socket, not
just by twisting the feet) in the direction you want to
go. This is called steering the skis.

Most of your weight must be on the outside ski, and
above all your hands must be forward.

But, above *all else* understand the most basic thing
about turning a pair of skis. To turn left, your body
must be on the left side of the skis, to turn right your
body must be on the right side of the skis, maybe a little
maybe a lot, depending on the speed at which you are
turning. At low speeds, simply move only your *hips*
to the inside of the turn, and leave your shoulders
centered over the skis. This is called crossover. You
need to cross your body over the skis, or later on, maybe
cross the skis under your body, back and forth in short
radius turns.

Say you have three pair of Salomon Crossmax skis
(the same kind of ski) in different lengths. The longest
pair will be more stable at a given speed than the
shorter pairs. The shorter pairs will start wandering all
over the place before the longest pair will.

I hope this helps.

In article ,
(Mark A Framness) wrote:

Greetings,

A few questions on the basic working of skis.

How does edging create a turn? One ski going flat and straight down
the fall line goes straight. Lean the ski on edge and it turns.

The sidecut of the skis (skis are wider at tip and tail than in the
middle: sidecut) causes the ski to bend into an arc when edged.


Now downhillers & GSers tend to use long skis. Why is this? Do the
longer skis provide more stability?

Yes. And downhill and GS courses need longer radius turns.

--
Alan Baker
Vancouver, British Columbia
"If you raise the ceiling 4 feet, move the fireplace from that wall
to that wall, you'll still only get the full stereophonic effect
if you sit in the bottom of that cupboard."

"foot2foot" wrote in message ...
"Mark A Framness" wrote in message
om...
Greetings,

A few questions on the basic working of skis.

How does edging create a turn? One ski going flat and straight down
the fall line goes straight. Lean the ski on edge and it turns.

Now downhillers & GSers tend to use long skis. Why is this? Do the
longer skis provide more stability?

Thanks


Say you have three pair of Salomon Crossmax skis
(the same kind of ski) in different lengths. The longest
pair will be more stable at a given speed than the
shorter pairs. The shorter pairs will start wandering all
over the place before the longest pair will.

This is what I was after plus more of the physics/mechanics of what is
going on. I am sorta looking for some new boards. I have been on 190
cm K2 3s now for going 4/5 years or so. Recently I demo'ed some K2
Escapes at 167 cm. Probably on the short side for me (6'2" @ 225 lb.s)
but they skied nice. I could carve at lower speeds and at higher
speeds they seemed fine. Generally I ski on groomers and nothing too
crazy, as I live in WI and ski in WI & the UP of MI (Brule, Blackjack,
Whitecap (WI hill), Powderhorn, have not been to Bohemia or the
Porcupines). Skiing on a mountain is just a dream for me at the
moment. :-(

The day before I demo'ed 'em we had about a foot of snowfall and hence
there were icey chutes down the center of the runs and crud on the
sides. So I figured it might be worth it to demo shorter more shaped
skis. I was right. In any event on the shorter skis or my regular
boards I eventually became used to the crud and started skiing in it.
It was fun.

It all got me to thinking about how skis actually do their business
(which I can make them do, ask me not how) so I can be a more
intelligent skier and ski purchaser.

Since I generally like to make bigger radius turns at higher speeds it
seems I want to use a longer ski.

Thanks

"Mark A Framness" wrote in message

Since I generally like to make bigger radius turns at higher speeds it
seems I want to use a longer ski.

Thanks

So, there I go assuming you're a newbie, and it turns out
you're an accomplished skier.

There also exists a general distinction between what would
be a "racing/groomie/ice/carving ski and an "all mountain ski".

If you have crud, cut up powder, or general rough snow
conditions, or even uncut ungroomed snow, an all mountain
ski will allow you to go fast, (and probably won't come alive
until you do) because it will give, then snap back to absorb
each little bump or rut. They "absorb the terrain".
These skis, being "softer" will do well in powder also.

The carving/racing ski will beat the crap out of you in
crud, because it's stiff, it's designed to hold on groom or
ice at higher speeds instead of washing out and skidding.

There are skis that try to "split the middle" so to speak, and
compromise between soft and hard.

Interestingly enough, many people feel that some of the
K2's a bit farther up the "for the advanced skier" scale
do split the middle very well. As far as I know, the
Escape if more of an intermediate ski, that is, it is soft
to make it easier to turn, and to "forgive mistakes" while
sacrificing real performance at speed.

I have seven pairs of skis. It's really a problem carrying
them all.

The other day, I went 42 MPH on a pair of 150 carvers,
and didn't even notice I had until I checked my gps.
Length isn't everything, but it's a factor to consider.
Do you plan on going 60 a lot?

Try out lots of different brands of skis, and try the same
ski in different lengths. You seem to know yourself
pretty well. Sooner or later one will stand out.

If you were curious about the actual mechanics of skiing,
I could run down a quick list. As far as the actual
"physics" of why this ski chatters and that ski doesn't,
I'm at a loss.

"foot2foot" wrote in message ...
"Mark A Framness" wrote in message

Since I generally like to make bigger radius turns at higher speeds it
seems I want to use a longer ski.

Thanks

So, there I go assuming you're a newbie, and it turns out
you're an accomplished skier.

Well I gave no indication of my experience level. Also that is
probably a question more newbies than veterans ask.



There also exists a general distinction between what would
be a "racing/groomie/ice/carving ski and an "all mountain ski".

If you have crud, cut up powder, or general rough snow
conditions, or even uncut ungroomed snow, an all mountain
ski will allow you to go fast, (and probably won't come alive
until you do) because it will give, then snap back to absorb
each little bump or rut. They "absorb the terrain".
These skis, being "softer" will do well in powder also.

The carving/racing ski will beat the crap out of you in
crud, because it's stiff, it's designed to hold on groom or
ice at higher speeds instead of washing out and skidding.

There are skis that try to "split the middle" so to speak, and
compromise between soft and hard.

Interestingly enough, many people feel that some of the
K2's a bit farther up the "for the advanced skier" scale
do split the middle very well. As far as I know, the
Escape if more of an intermediate ski, that is, it is soft
to make it easier to turn, and to "forgive mistakes" while
sacrificing real performance at speed.

I have seven pairs of skis. It's really a problem carrying
them all.

The other day, I went 42 MPH on a pair of 150 carvers,
and didn't even notice I had until I checked my gps.
Length isn't everything, but it's a factor to consider.
Do you plan on going 60 a lot?

Hahaha! I would like to be able to do that someday, but no hill I ski
on is long enough to develop that kind of speed! The hill I ski on
most often has three runs where one can get some speed going. Two are
due to a moderate pitch and another is a combination of pitch &
length. However, I do not think we are talking anywhere near the
speeds you suggest. I should glom on to my Bro's GPS and see if I can
get a notion of that!




Try out lots of different brands of skis, and try the same
ski in different lengths. You seem to know yourself
pretty well. Sooner or later one will stand out.

If you were curious about the actual mechanics of skiing,
I could run down a quick list. As far as the actual
"physics" of why this ski chatters and that ski doesn't,
I'm at a loss.


Thanks some real good pointers there!

Actually I dug up a book I had bopping about the house. "How the
Racers Ski" (1972 W. W. Norton & Company) by Warrem Witherell. The
book starts off by talking about the design of skis. The main terms
brought out in this section are camber, reverse-camber, flexion,
sidecut, and torsion. When I read further it became apparent what
happens in a carve. The edge goes in and then skiers by their action
cause the skis to flex. The skis then form an arc and a turn ensues.

What I never got was why should edging cause a turn. Take a knife put
it into the snow and walk downhill with it, it tracks straight. The
missing pars was, of course, skis are flexible.

All points bulletin!
If you just starting to ski, DO NOT get the book and read it! Get on
the slopes and ski! I would suggest reading the book have you consider
yourself to be an intermediate or better skier.

Anyway thanks!

Mark A Framness wrote:

What I never got was why should edging cause a turn. Take a knife put
it into the snow and walk downhill with it, it tracks straight. The
missing pars was, of course, skis are flexible.

Actually, he missing part is that ski edges are curved. Take a look
at any ski made in the last 5 years and you'll see that it's wide at
the tip, narrow in the waist, and wide at the tail. Put it on edge
and the ski follows the curve defined by the edge. Wider tips & tails
relative to the waist == tighter turn.

Sure, bending the ski will make the turn tighter, but it's the curve
built into the shape of the ski that makes it turn when you put it on
edge.

Note that skis have always had a curved edge. Modern skis have a lot
of curve (aka sidecut) so it's easy to see what's going on, but even
skis from the turn of the century had a curved edge. Put 'em on edge
and they turn. For traditional sidecut skis you had to really bend
them to make them carve a tight turn; modern skis carve short turns
more easily.

All points bulletin!
If you just starting to ski, DO NOT get the book and read it! Get on
the slopes and ski! I would suggest reading the book have you consider
yourself to be an intermediate or better skier.

Agreed. Learn to ski by skiing, not by reading.


--
// Walt
//
// There is no Volkl Conspiracy

(Mark A Framness) writes:

"foot2foot" wrote in message ...
[big snip]
Try out lots of different brands of skis, and try the same
ski in different lengths. You seem to know yourself
pretty well. Sooner or later one will stand out.

If you were curious about the actual mechanics of skiing,
I could run down a quick list. As far as the actual
"physics" of why this ski chatters and that ski doesn't,
I'm at a loss.


Thanks some real good pointers there!

Actually I dug up a book I had bopping about the house. "How the
Racers Ski" (1972 W. W. Norton & Company) by Warrem Witherell. The
book starts off by talking about the design of skis. The main terms
brought out in this section are camber, reverse-camber, flexion,
sidecut, and torsion. When I read further it became apparent what
happens in a carve. The edge goes in and then skiers by their action
cause the skis to flex. The skis then form an arc and a turn ensues.

What I never got was why should edging cause a turn. Take a knife put
it into the snow and walk downhill with it, it tracks straight. The
missing pars was, of course, skis are flexible.

Well, yeah, but while the laws of physics haven't changed in the 32
years since that book was written, ski design has changed -- a lot.
If you're using a pair of 1972-vintage skis, what Witherell says has
a lot of bearing. If you're using something more recent, it'll
probably hurt more than help.

All points bulletin!
If you just starting to ski, DO NOT get the book and read it! Get on
the slopes and ski! I would suggest reading the book have you consider
yourself to be an intermediate or better skier.

....and into nostalgia ;-)

--
:::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::::::::::::::
Mary Malmros
Some days you're the windshield,
Other days you're the bug.

"Walt" wrote in message
...

Sure, bending the ski will make the turn tighter, but it's the curve
built into the shape of the ski that makes it turn when you put it on
edge.

Actually, I believe that bending the ski is necessary to make it carve. The
sidecut is what makes it bend into an arc (or at least makes it easier to
bend into an arc).

Here's a little home experiment that was in Skiing (or maybe Ski) magazine
at least a quarter of a century ago:

Take an index card or a piece of paper.

Cut a gentle "sidecut" out on one side (a "sidecut" being a concave arc
along the edge of the paper)

Set it on a table "on edge:" so that the two ends of the arc rest against
the table, and the card is tilted at an angle of 45 degrees or so.

Push (or just blow) gently on the middle of the arc until it contacts the
table.

Voila: the card contacts the table along an arc. That's the arc the ski
would carve around.

A few notes: The arc on the table can be considerably tighter (smaller
radius than) the arc of the sidecut. The more you tip the card up from
horizontal, the tighter the carving arc. There are some more variables at
work on skis: for one thing, the snow (unless it's really rock hard)
deforms. Also, torsional flex (twisting) of the ski comes into play.

"sjjohnston" wrote in message ...
"Walt" wrote in message
...

Sure, bending the ski will make the turn tighter, but it's the curve
built into the shape of the ski that makes it turn when you put it on
edge.

Actually, I believe that bending the ski is necessary to make it carve. The
sidecut is what makes it bend into an arc (or at least makes it easier to
bend into an arc).

I am going to disagree (politely and I hope persuasively) super
sidecuts by themselves are responsible for carving and that the advice
I am reading is out to lunch due to modern gear.

The skis at the time of the writing of that book had sidecut, in fact
Mr. Witherell refers to sidecut being a key ski-design factor.
Obviously, the average side cut on skis is greatly increased from
those days.

What is going on is the skier turns the ski onto edge, the edges at
the tip and the tail engage the surface, the skier than either from
their weight, centrifugal force, or from torqueing the ski forward
(leaning your shins into your boots) or backward cause the ski to bend
(the term used is reverse-camber). Remember the tip and the tail are
locked in and the center of the ski is free (or more so than the tip &
tail), so the combination of your weight and the centrifugal force
cause the ski to bend and you turn along that bend.

This is why one can carve at a lower speed with a super-sidecut
because one does not have to lean over so much to engage the tip and
tail edges. The more one leans the more centrifugal force one needs to
keep from falling (i.e. a tighter turn or more speed), hence this is
why super-sidecuts allow for easier carving one does not have to be
going so fast to carve. Something I noticed almost immediately upon
putting some demos which had more sidecut than my skis (K2 3s compared
to the K2 Escape).

Now, take an free ski and put it on edge and push it. What does it do?
It carves a turn in the opposite direction from what one would expect.
This is because the ski in its natural state is not flat, but has
camber (i.e. bows up from a flat surface).


A few notes: The arc on the table can be considerably tighter (smaller
radius than) the arc of the sidecut. The more you tip the card up from
horizontal, the tighter the carving arc. There are some more variables at
work on skis: for one thing, the snow (unless it's really rock hard)
deforms. Also, torsional flex (twisting) of the ski comes into play.

The arc depends upon how tightly the skier can bend the ski.