Ski fitting question

A simple question that I hope has a simple answer.
Father and son both want the same ski for the same conditions, same
trails and races, e.g., an Atomic RSII for soft cold snow; both are 5'
7" and weigh 140 lbs; son is 25 and a strong skier in all respects
while dad still has decent technique and balance but is 30 years older
and doesn't have his son's strength, VO2 max, etc.
Does a good ski fitter simply put dad on a slightly softer version of
his son's ski?
Thanks.
Russ

Hi Russ - The answer is yes, and no. The primary consideration is to
fit the ski at full-weight for optimal glide/handling characteristics.
So while there may be differences between the optimal skis for both of
you (I'm assuming this is you we're talking about), they're going to
look pretty similar when they're loaded to 100% body weight.

So where are the differences? Generally, a stronger skier will
appreciate a more "active" ski. I look at camber action in two ways.
One is to look at the half-weight camber height, or the difference
between half and full weight camber height. The greater the difference
the more "lively" the ski will feel. The other consideration is what I
call the overload response of the ski. I measure that by loading the
ski to 120% of body weight and measuring the camber response from 100%
load. These numbers are small (generally in the range of 0.20 mm, plus
or minus). You don't necessarily feel this measurement the way you feel
the half/full weight camber height differential. But this measurement
is a good indication of the intangible feeling of a ski "giving back"
or alternatively absorbing too much energy. The idea is that, as you
impulsively load a ski beyond full weight, the ski can absorb some
energy. If you're able to load the ski strongly, and are technically
capable and ski in a good position, the ski will return that energy in
a positive way and will feel very rewarding. If you're not as strong,
or ski a little back on your feet, then the ski will feel like it's
fighting you. I generally aim for the middle of the road, but try to go
a bit low on overload response for somebody who is focused on
marathons, or who is not an agressive racer.

In terms of factory flex numbers it usually breaks down to a better
skier prefering a higher half-weight camber (on Atomics that's a number
in the range of about 2.2 to maybe 2.8 on the sticker for a skier your
size) and sometimes even a lower closing flex (or "mid-flex" in the
Atomic jargon - a number in the low 60s on the sticker for skis that
will fit you). But these ar basically just starting ranges for more
careful measurement.

Incidentally, the new World Cup skating skis (next year's model) are
much more lively feeling skis than last year's RS:11. So even skis that
measure the same will have very different feelings. I happen to be
exactly the size you're talking about, and tested the new skis on snow
this winter. You can read about it at my website if you're interested:
http://www.engineeredtuning.net/NewAtomic.htm

Good luck!

Zach


wrote:
A simple question that I hope has a simple answer.
Father and son both want the same ski for the same conditions, same
trails and races, e.g., an Atomic RSII for soft cold snow; both are 5'
7" and weigh 140 lbs; son is 25 and a strong skier in all respects
while dad still has decent technique and balance but is 30 years older
and doesn't have his son's strength, VO2 max, etc.
Does a good ski fitter simply put dad on a slightly softer version of
his son's ski?
Thanks.
Russ

Zach,

Thanks for the reply - the 120% body weight measurement is very
interesting.

I ski the RSII (as well as a couple of Fischers and Rossis) and I look
forward to trying the new Atomic, although I really just picked the
Atomic brand out of the air, in the hope that anyone who replied to my
question wouldn't recommend different brands of skis for the two
skiers.
Would you use the same fitting approach for the other big name skis as
well, such as Fischer, Rossi and Madshus? I've heard some folks say
that fitting a Rossi is different than fitting the others but I don't
know enough about this to know just what they mean.

Thanks again,
Russ

The considerations are the same Russ, although the characteristics of
the different models require different strategies. It takes a little
while to understand what range of values a given model of ski is
designed to have - where "normal" is, and how adjustments either side
of that effect the performance of the ski. I'd be confident with
Atomic, Fischer and Madshus because I work with them extensively. I
have less experience with Rossi because I don't sell them. But it's
been my impression that with their most recent skate models they've
come more in-line with what the rest of the industry is building.
They're very nice skis in any case.

Zach

Zach,

Thanks once again - it's always enjoyable to read your thoughtful
comments.

Russ

Good question. My feeling is that it mostly comes down to a matter of
personal preference. Everybody is making skis with tremendous stability
and really good speed characteristics. It certainly makes sense to
taylor selections to the strength of a product line, and some lines are
stronger in some areas than others. But on the whole I think just about
any skiers could be made very happy on any of the major brands.

Talking about skate skis now, in terms of individual tendencies, I'd
say that a given Fischer (because of their very hard finish and
relatively high residual camber at full weight) will tend to fit the
broadest range of skiers weights. Atomic and Madshus need to be fit
somewhat more precisely. Madshus tends to have the longest and
"coolest" pressure distribution, which means that it's easy to pick a
ski geared toward low static friction, and soft snow performance
characteristics. But again, these are generalizations that shouldn't be
considered "rules".

Zach

Thanks. I've been very happy with my old (~5+ y.o.) Fischer RCS skate
skis. But my newer Atomic RC11 striding skis are terrific, I really
like them a lot. So, I'm thinking of looking at Atomic RS11's for my
next pair of skate skis because of my good luck with the RC11's. But,
what I'll really do is look at the 6 major brands sold in my town
(Karhu, Solomon, Fischer, Rossi, Atomic, Madshus), all sold by good
techs, and decide based on their opinion of individual skis. I might
even be able to ski on some.... Or maybe contact you 8-).

Another point - "feel" - tell me what you think about this. I have two
pair of classic skis, both, well fitted to me at the time I bought
them: A pair of Madshus from the mid 90s, top of the line at the time
and the above pair of '04/'05 Atomic RC11s. I have always liked the
Madshus just fine in terms of climbing and speed. But since getting
the Atomics, I think the Atomics are easier to wax for better climbing
and seem MUCH more stable on the downhills, especially fast turns.
Overall gliding speed is similar, but I don't do real serious wax
testing - close enough is good enough for my purposes. But the subtle
feel is quite different. Although I prefer to ski on the Atomics, the
Madshus just seem "smoother". I dont' know how else to describe it -
smooth and silky. The Atomics seem somehow noisier and just feel
"rougher". This is all very subtle though and in no way detracts from
my overall preference for the Atomics..

Just musing, trying to get up the energy to storage wax my family's 15
or so pair of skis!

Cam

Yeah, I'd say you've pretty accurately described what I would call the
typical strengths of the Madshus and Atomic classic skis of the
vintages you're talking about. People tend to describe Madshus stuff as
"smooth" across the board. The RC11s are known as really good skis for
stability - perhaps in part because of a fairly wide tip and quite a
lot of sidecut compared to other skis in the industry. They also tend
to end up a bit shorter than other brands on the classic side of
things. I wouldn't be surprised if your Atomics were 9cm shorter than
your Madshus.

Incidentally, Madshus classic skis have become quite a lot more precise
in terms of pocket shape and placement in the past several years. So
it's likely that a newer Madshus would compare on more equal footing
with the Atomic with regard to the ease of waxing for kick.

The new Atomic skate ski is a really nice ski - it's called a WorldCup
now instead of an RS:11. I would definitely put it on your list. But if
you have the opportunity to test stuff through your local retailers you
should definitely take advantage, especialy if your point of reference
is a five year old Fischer. Sounds like you've got some really good
local resources - you should have no need to contact me unless you want
something very specific.

Zach


Camilo wrote:
Thanks. I've been very happy with my old (~5+ y.o.) Fischer RCS skate
skis. But my newer Atomic RC11 striding skis are terrific, I really
like them a lot. So, I'm thinking of looking at Atomic RS11's for my
next pair of skate skis because of my good luck with the RC11's. But,
what I'll really do is look at the 6 major brands sold in my town
(Karhu, Solomon, Fischer, Rossi, Atomic, Madshus), all sold by good
techs, and decide based on their opinion of individual skis. I might
even be able to ski on some.... Or maybe contact you 8-).

Another point - "feel" - tell me what you think about this. I have two
pair of classic skis, both, well fitted to me at the time I bought
them: A pair of Madshus from the mid 90s, top of the line at the time
and the above pair of '04/'05 Atomic RC11s. I have always liked the
Madshus just fine in terms of climbing and speed. But since getting
the Atomics, I think the Atomics are easier to wax for better climbing
and seem MUCH more stable on the downhills, especially fast turns.
Overall gliding speed is similar, but I don't do real serious wax
testing - close enough is good enough for my purposes. But the subtle
feel is quite different. Although I prefer to ski on the Atomics, the
Madshus just seem "smoother". I dont' know how else to describe it -
smooth and silky. The Atomics seem somehow noisier and just feel
"rougher". This is all very subtle though and in no way detracts from
my overall preference for the Atomics..

Just musing, trying to get up the energy to storage wax my family's 15
or so pair of skis!

Cam

Thanks for your comments Zach. Interesting what you said about the
length of the RC11 vs Madshus. You are correct. I'm not sure if it's
9 cm or some number less than that (the difference), but it's
significant. In fact, as I was writing about the stability in my post
above, I had originally written - the Atomics are more stable in spite
of being shorter! But then I took that statement out thinking - that
could be exactly why they feel better around corners - but I'm sure
it's counterintuitive for straight on speed stability. Anyway,
they're all good skis (all the ones I have), but if you ski enough you
begin to notice these things. Thanks for sharing your experiences and
knowledge.

Zach Caldwell wrote:
Hi Russ - The answer is yes, and no. The primary consideration is to
fit the ski at full-weight for optimal glide/handling characteristics.
So while there may be differences between the optimal skis for both of
you (I'm assuming this is you we're talking about), they're going to
look pretty similar when they're loaded to 100% body weight.

So where are the differences? Generally, a stronger skier will
appreciate a more "active" ski. I look at camber action in two ways.
One is to look at the half-weight camber height, or the difference
between half and full weight camber height. The greater the difference
the more "lively" the ski will feel. The other consideration is what I
call the overload response of the ski. I measure that by loading the
ski to 120% of body weight and measuring the camber response from 100%
load. These numbers are small (generally in the range of 0.20 mm, plus
or minus). You don't necessarily feel this measurement the way you feel
the half/full weight camber height differential. But this measurement
is a good indication of the intangible feeling of a ski "giving back"
or alternatively absorbing too much energy. The idea is that, as you
impulsively load a ski beyond full weight, the ski can absorb some
energy. If you're able to load the ski strongly, and are technically
capable and ski in a good position, the ski will return that energy in
a positive way and will feel very rewarding. If you're not as strong,
or ski a little back on your feet, then the ski will feel like it's
fighting you. I generally aim for the middle of the road, but try to go
a bit low on overload response for somebody who is focused on
marathons, or who is not an agressive racer.

In terms of factory flex numbers it usually breaks down to a better
skier prefering a higher half-weight camber (on Atomics that's a number
in the range of about 2.2 to maybe 2.8 on the sticker for a skier your
size) and sometimes even a lower closing flex (or "mid-flex" in the
Atomic jargon - a number in the low 60s on the sticker for skis that
will fit you). But these ar basically just starting ranges for more
careful measurement.

Incidentally, the new World Cup skating skis (next year's model) are
much more lively feeling skis than last year's RS:11. So even skis that
measure the same will have very different feelings. I happen to be
exactly the size you're talking about, and tested the new skis on snow
this winter. You can read about it at my website if you're interested:
http://www.engineeredtuning.net/NewAtomic.htm

Good luck!

Zach


wrote:

A simple question that I hope has a simple answer.
Father and son both want the same ski for the same conditions, same
trails and races, e.g., an Atomic RSII for soft cold snow; both are 5'
7" and weigh 140 lbs; son is 25 and a strong skier in all respects
while dad still has decent technique and balance but is 30 years older
and doesn't have his son's strength, VO2 max, etc.
Does a good ski fitter simply put dad on a slightly softer version of
his son's ski?
Thanks.
Russ


How can one put 120% of body weight on a ski? One can jump up and come
down on a ski but one cannot push down harder than their weight since
they have nothing from which to push?