150 combis for skating?

Hi,

Looks like I'm ready to take the plunge for the Aeros. I think this has
been mentioned here as a possibility, but I don't recall anyone
actually sharing their experience using the longer 150 combis for
skating - i.e. putting on regular wheels with no clutch. Any potential
issues with that? Other than the added weight, can additional length be
bad for technique? This would be counterintuitive given how long snow
skis are.

Thanks a bunch!

My dealers says that mine should be on their ways as I'm typing this.
When they come in, I'll mount them up with SNS Pilot bindings and Salomon
Active Pilot boots and report back, if possible with video footage.
How much weight would a couple inches of alu bar add? Enough so you could
tell? The front wheel especially would be further out I guess, which you may
notice when changing the ski's direction.
Unexpereinced as I am, despite being a terrible (recovering) weightweenie on
bikes, weight with rollerski's doesn't scare the the least bit. My
Crosskates are like bricks, but I *seem* to be able to skate then just fine,
at least on my flatlands.

Myself I've got legs so long that with the rule of proportions, I should be
able to handle the SC's better than the average skier does the S's.

I wonder how wheelbase affects skate technique. Racers use the shortest
ski's allowed for some reason. Just weight? To be able to turn like on
inline skates without stepping through the turn? As long as my Aero's are
the closest thing to ski's, I'm happy.

"Larry" schreef in bericht
ups.com...
Hi,

Looks like I'm ready to take the plunge for the Aeros. I think this has
been mentioned here as a possibility, but I don't recall anyone
actually sharing their experience using the longer 150 combis for
skating - i.e. putting on regular wheels with no clutch. Any potential
issues with that? Other than the added weight, can additional length be
bad for technique? This would be counterintuitive given how long snow
skis are.

Thanks a bunch!

Jan Gerrit Klok wrote
I wonder how wheelbase affects skate technique.

Here's some ideas . . .
(a) Longer rollerski makes it more difficult to steer the rollerski by
direct rotation about the vertical axis -- so in that respect more like a
snow ski and less like an inline-skate.
Advantages:
* less temptation to try cute inline-skate steering moves -- though you
could just decide not to allow yourself to do them.
* less possibility of unconsciously curving the path of the ski while
pushing, in a way that would increase friction on snow.
* a little more stability of straight running when hitting irregularities
on the ground.
Disadvantage:
* when a dog pops out in front of you, you might wish you had maximum
steering capability.
* I suspect some "snow-plow" or "wedge" braking on rollerskis is easier to
control if you can apply higher rotational forces.

(b) Longer rollerski makes it more difficult when recovering the foot inward
while its up in the air to do extra circular-path and foot-twist moves which
are effective with an inline-skate -- but not possible with a normal-length
snow-ski (because the ski tip would poke into the snow).
Advantage:
* You don't fall into a thru-the-air moves which don't work on snow.
* But . . . 2 inches more isn't enough to stop these extra air moves.
Mitigation:
* consciously practice recovering the rollerski in a motion that will work
for snow-skis.
* or don't worry about it, since my experience is that when winter comes
it's trivial to notice and fix the "problem" in the first five minutes on
snow.
Disadvantage:
* if you get off balance and need to recover, longer ski up in the air is
more difficult to control, less likely to get it into a stable configuration
before it touches ground again -- more likely to fall.
* Fear is one of the big problems with improving skiing technique + balance
on pavement. If shorter rollerskis make you feel more confident of
recovering from a near-fall, you're more confident to expand your "envelope"
of balance (e.g. like playing with riding on the outside edge)

(c) Heavier ski
Advantage:
* specific training for skating in the backcountry on a wider ski with
metal edges.
Disadvantage:
* lower "turnover" frequency -- difficult to achieve and sustain as many
stroke cycles per minute as you can perform with a light racing snow-ski.
* I think higher turnover of leg-pushes is important for surviving a steep
hill without too much fatigue for the remainder of the event.
* so a heavier rollerski means you're not training at the point of your
Force-versus-Speed curve which you'll be using in the most critical parts of
your on-snow performance.

My first rollerskis were Jenex Aero SC 150, and I skated on them lots. I'm
not tall, so I had bought the Combi rollerskis so I could also do Classic
with them. I didn't notice any problem skating with rollerskis longer than
"proportional" for my height -- but that was back years ago when I didn't
know what effective skating was supposed to feel like anyway. I haven't
tried skating on them since.

Having said all that, if Jenex says the SC is better for taller skiers,
there's probably some good reason. I would just want to know what the reason
is, so I could decide if it fit with my goals.

Ken

P.S. Jan Gerrit Klok wrote
. . . the rule of proportions . . .

Is that Newton's Law of Proportions? or the Laplace rule of proportions? or
Poincare's lemma of proportions. I will hereby offer the "Roberts rule of
proportions":
"Lots of things which smart people who haven't done the detailed analysis
_think_ are proportional -- really aren't."

(d) Longer rollerski tends to put more stress along cross-sectional planes
near the middle of the big "main bar" connecting the two wheels.
Disadvantage:
* higher stress can result in more "metal fatigue".
* sometimes things subject to more "metal fatigue" can break.

Jan Gerrit Klok wrote
How much weight would a couple inches of aluminum bar add?

Are you sure that Jenex uses an aluminum bar in the model SC 150 rollerski?

Anyone know about the metal fatigue characteristics of aluminum versus steel
or other materials?

Ken

whoops -- My last point (d) was misleading. It is not true that longer
rollerskis should have more cross-sectional stress or more problem with
metal fatigue. Stress and metal fatigue are well-understood factors which a
competent mechanical designer know how to deal with.

So let me offer this attempt to fix it with a better point (d):

(d) Other things being equal (which they never are), a longer rollerski
tends to put more stress along cross-sectional planes near the middle of the
big "main bar" connecting the two wheels, when the skier's weight it on it.
But . . .
* a longer rollerski whose "main bar" also has a larger cross-sectional
area could actually have _lower_ stress -- of course other things being
equal this would add yet more weight to the longer ski.

* other clever design changes might put reduce transmission of road-impact
shock and vibrations to there was less stress even with keeping the same
cross-sectional area.

* the design shape of the cross-section -- or the materials or fabrication
of the "main bar" -- might be changed to be stronger to withstand expected
higher stress.

* the shorter version of the rollerski might already be so strong and
"over-designed" to handle metal fatigue that the expected usage life is so
long that that just making a little longer isn't relevant to any realistic
human user.

* Skating with smooth "continuous" technique likely puts less vertical
stress on the cross-section of a rollerski than strong Classic striding
where the foot finishes way up off the ground.

Ken

"Ken Roberts" schreef in bericht
...
Having said all that, if Jenex says the SC is better for taller skiers,
there's probably some good reason. I would just want to know what the
reason
is, so I could decide if it fit with my goals.
They were suggested to me specifically for use with the Aero heel mounted
brake. It requires some extra room between boot (binding) and the rear
wheel, with large boots bringing the bindings (too) close to the front
wheel). Probably messing up weight distribution at push-off.
They just said the longer SC's work out better with size 12+ boots that the
S's.
When I threw in that taller athletes might handle longer ski's better
anyway, I just got an "exactly".

P.S. Jan Gerrit Klok wrote
. . . the rule of proportions . . .

Is that Newton's Law of Proportions? or the Laplace rule of proportions?
or
Poincare's lemma of proportions. I will hereby offer the "Roberts rule of
proportions":
"Lots of things which smart people who haven't done the detailed analysis
_think_ are proportional -- really aren't."
Proportions may not always end up being 1:1 in an ideal situation, but I
doubt there are any axamples in performance sports where one size of
something is best for all. Whether it's wheelsize on bikes, handlebar width,
grip handle thickness, shoe size, when the athlete is bigger in the relavant
places (or overall weight/strength), you'll want it bigger.
Added weight and length may not hurt a taller athlete, as in general he'll
move at a lower cadance anyway? If not, taller skier's were proportionately
faster also.

On Oct 13, 12:02 pm, "Ken Roberts" wrote:

...if Jenex says the SC is better for taller skiers,
there's probably some good reason. I would just want to know what the reason
is, so I could decide if it fit with my goals...

Ken, we were taking to Coach Sten Fjeldheim at our Fall Skating Clinic,
and he made the observation that the V2 Aero 150 is so heavy, the
binding can't keep the rear wheel from dragging. This results in the
tendency for Aero 150 skiers to pick up their leg in order for the rear
wheel to clear the ground.

Taller skiers tend to have longer feet, thus the binding is mounted
further forward on the shaft. This exacerbates the problem - more of
the ski wieght is behind the binding pivot point, and there's no
binding out there will pull the rear of the ski back up to the boot.

I think Jenex knows about the problem, so recommends the longer ski for
people with longer feet - taller people!

An alternative to the problem - Sten suggestion - is to drill a hole
through the heel of your ski boot, put a short piece of coat hanger or
other wire through it, then hook the ends to a strong rubber band that
goes around the ski shaft. This would assist in returning the rollerski
to the boot.

My recommendation is to get the lightest ski for your skiing
conditions...

Mike

Even before I get my Aero's in, I'm already expecting to put elasticbands on
it. Hoping to keep it much simpler than your (probably better) suggestion,
though.
If the rear is too heavy, perhaps I'll just weigh the front some extra :-)

Is this balance issue also why rollerski racers seem to put their bindings
as far aft on their rollerskis as possible? I think I'll like a bit more
rear end length, to prevent me from tipping back over (I get careless).

"NordicSkiRacer" schreef in bericht
oups.com...
On Oct 13, 12:02 pm, "Ken Roberts" wrote:

...if Jenex says the SC is better for taller skiers,
there's probably some good reason. I would just want to know what the
reason
is, so I could decide if it fit with my goals...

Ken, we were taking to Coach Sten Fjeldheim at our Fall Skating Clinic,
and he made the observation that the V2 Aero 150 is so heavy, the
binding can't keep the rear wheel from dragging. This results in the
tendency for Aero 150 skiers to pick up their leg in order for the rear
wheel to clear the ground.

Taller skiers tend to have longer feet, thus the binding is mounted
further forward on the shaft. This exacerbates the problem - more of
the ski wieght is behind the binding pivot point, and there's no
binding out there will pull the rear of the ski back up to the boot.

I think Jenex knows about the problem, so recommends the longer ski for
people with longer feet - taller people!

An alternative to the problem - Sten suggestion - is to drill a hole
through the heel of your ski boot, put a short piece of coat hanger or
other wire through it, then hook the ends to a strong rubber band that
goes around the ski shaft. This would assist in returning the rollerski
to the boot.

My recommendation is to get the lightest ski for your skiing
conditions...

Mike

I don't think it's even possible to snowplow the Aeros of any length.
The tire rubber's just too sticky. Get the speed reducers and /or the
brake to slow down.

Aluminum is what's used for the whole chassis of the Aeros. Aluminum
has much worse fatigue characteristics than steel. Go to
Nordicskiracer.com and look for a post in the last month with a photo
of aan aluminun classic roller ski shaft that failed right under the
binding. I've had three or four rear forks on my used-for-classic-only
Aero SCs fail, always on the side where I use an outrigger.

Randy
Ken Roberts wrote:
Jan Gerrit Klok wrote
I wonder how wheelbase affects skate technique.

Here's some ideas . . .
(a) Longer rollerski makes it more difficult to steer the rollerski by
direct rotation about the vertical axis -- so in that respect more like a
snow ski and less like an inline-skate.
Advantages:
* less temptation to try cute inline-skate steering moves -- though you
could just decide not to allow yourself to do them.
* less possibility of unconsciously curving the path of the ski while
pushing, in a way that would increase friction on snow.
* a little more stability of straight running when hitting irregularities
on the ground.
Disadvantage:
* when a dog pops out in front of you, you might wish you had maximum
steering capability.
* I suspect some "snow-plow" or "wedge" braking on rollerskis is easier to
control if you can apply higher rotational forces.

(b) Longer rollerski makes it more difficult when recovering the foot inward
while its up in the air to do extra circular-path and foot-twist moves which
are effective with an inline-skate -- but not possible with a normal-length
snow-ski (because the ski tip would poke into the snow).
Advantage:
* You don't fall into a thru-the-air moves which don't work on snow.
* But . . . 2 inches more isn't enough to stop these extra air moves.
Mitigation:
* consciously practice recovering the rollerski in a motion that will work
for snow-skis.
* or don't worry about it, since my experience is that when winter comes
it's trivial to notice and fix the "problem" in the first five minutes on
snow.
Disadvantage:
* if you get off balance and need to recover, longer ski up in the air is
more difficult to control, less likely to get it into a stable configuration
before it touches ground again -- more likely to fall.
* Fear is one of the big problems with improving skiing technique + balance
on pavement. If shorter rollerskis make you feel more confident of
recovering from a near-fall, you're more confident to expand your "envelope"
of balance (e.g. like playing with riding on the outside edge)

(c) Heavier ski
Advantage:
* specific training for skating in the backcountry on a wider ski with
metal edges.
Disadvantage:
* lower "turnover" frequency -- difficult to achieve and sustain as many
stroke cycles per minute as you can perform with a light racing snow-ski.
* I think higher turnover of leg-pushes is important for surviving a steep
hill without too much fatigue for the remainder of the event.
* so a heavier rollerski means you're not training at the point of your
Force-versus-Speed curve which you'll be using in the most critical parts of
your on-snow performance.

My first rollerskis were Jenex Aero SC 150, and I skated on them lots. I'm
not tall, so I had bought the Combi rollerskis so I could also do Classic
with them. I didn't notice any problem skating with rollerskis longer than
"proportional" for my height -- but that was back years ago when I didn't
know what effective skating was supposed to feel like anyway. I haven't
tried skating on them since.

Having said all that, if Jenex says the SC is better for taller skiers,
there's probably some good reason. I would just want to know what the reason
is, so I could decide if it fit with my goals.

Ken

P.S. Jan Gerrit Klok wrote
. . . the rule of proportions . . .

Is that Newton's Law of Proportions? or the Laplace rule of proportions? or
Poincare's lemma of proportions. I will hereby offer the "Roberts rule of
proportions":
"Lots of things which smart people who haven't done the detailed analysis
_think_ are proportional -- really aren't."