Bindings and broken legs

[ ]

Maybe I'm doing something wrong. After all, my skiing is hardly
impeccable. But I can't count the number of times I've popped out of
my "non-safety" cable bindings. Admittedly, it's usually during a face
plant, when my T2's tend to flex and seemingly allow the toe to
twist/pull out of my Riva II cable bindings.

Those older/lighter cable bindings without a bar across the duckbill
actually has some degree of release, (mostly) based on deformation of
the duckbill. Heavier bindings with a toe bar, like Riva III, Cobra,
etc. does release like this.


Martin
--
"An ideal world is left as an exercise to the reader."
-Paul Graham, On Lisp

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In article ,
David Off wrote:
bbense+rec.skiing.backcountry.Dec.27.03@telemark. slac.stanford.edu wrote:
There's a lot
of engineering and standards in todays's Alpine bindings that
just aren't there in ANY AT binding[1].

The Naxo and Sk'Alp 8007, being based on Alpine bindings are probably as
safe.


_ What would be really interesting would be to put both alpine
boots and several different AT boots in those bindings and run
them through a bench tester. If they all release at the same
force, I would be suprised. Pleasantly surprised....

_ That's what really made the great advance in alpine bindings.
Now you can pretty much put any alpine boot of the same sole
length in a binding and get exactly the same release values
from a bench tester. BTW, I would really like to be wrong
about this, I would love it if some one popped up and said

"Here's the test and the data..., you're full of s####"

_ Booker C. Bense


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This is all very interesting, but in my experience, I don't ski as
aggressively in the backcountry as I do at the resorts.
For one thing, there is no ski-patrol around to carry your sorry butt off
the mountain if you get injured, so most of us in my circles are a LOT more
careful in the backcountry.
My second point is this: I have had several releases with my silvrettas,
with zero injury or even stress on the joints which would cause me concern.
I am 43, so those joints aren't as elastic as they once were. I think you
are spending too much mental energy worrying about a purely twisting
release, I mean, how often do you expect to encounter such a thing as you
tumble down the side of a mountain? Where, exactly, are you intending to
use your AT gear?
I experienced a number of twisting pressures on knees, ankles and hips while
learning to tele, the ski goes one way, you go another, the bindings are not
designed to release, this seems much more problematic to me than an AT
binding which releases at the heel in a twisting fall, one of the many
reasons that I am very willing to take the weight hit (measured in a few
ounces these days when comparing gear designed for more than just trail
touring) of AT over Tele.
Cheers, happy new-year, I'm going to go carve up some of the fresh powder
that is falling, damn buddy hasn't shown up yet so I thought I'd surf the
newsgroup...

Vince


"John Mason" wrote in message
...

"Frank Wiles" wrote in message
...

"John Mason" wrote in message
...
I saw on the Silvretta website that they rotate out at the back but I
am
not
convinced that this is of much use in the situation where the body is
rotating purely about the heel (much less useful compared to a toe
release
binding).

Do you own a pair John? I've got a couple pair of silvrettas and a pair
of
tourlites and they release just fine when a twisting motion is applied.

I rent silvrettas.


The reason is that there is so much more force required to break
open the binding at the heel than at the toe - measuring my foot I
measure
five times the distance from the toe to the ball of my foot compared
to
the
heel. This will roughly equate to five times the force needed to hold
the
foot safely in position at the heel compared to at the toe.

Bad science! A twisting force is a twisting force. Indeed, if the
twisting
force is acting from the leg's center, it would be acting at a greater
distance (and take more leverage) to pop out at the toe than it would to
pop
out the heel, would it not?. I just tried the experiment on my living
room
floor and they both (standard downhill binding & silvretta) take about
the
same force when set @ 7 to pop out.

I do not make any claim to do proper science, this is only theory and
common
sense. I am looking for evidence and information to support my thinking.

Your point is just the point I am making. It is because it takes so much
more force at the toe - perhaps five times the force compared to the heel
to
release the foot in a twisting fall that I cannot believe that the heel
release can provide the same protection as the toe yet hold the heel
sufficiently firmly to prevent a pre-release.

Try standing with the weight on your heel and rotate the body about the
lower leg's axis and see if the Silvretta pops out. I would be surprised
if
you can get them to release without also pushing to the side.


For what it's worth, I injured my ankle last year in a twisting fall
using
a
pair of standard downhill bindings. Never had a problem with the
silvrettas.

Many accidents occur in perfectly set up bindings and the accidents are
caused by applying forces to the knee or elsewhere in a way that the
bindings cannot give protection, for more info see:


http://www.ski-injury.com/knee.htm#M...MENT%20SPRAINS

I believe that the binding setting at the heel that is required to
allow
the
heel to brake away when it needs to will be so low that the binding
will
pre-release extremely easily.

Hmm, mine don't. Are you saying your's do, or do you know someone who
complains of this problem?

I am saying, as implied above that if you don't pre-release then you are
not
getting the same protection from a rotating injury that a toe release will
give.


This is just for a pure rotating fall such
that might cause a spiral fracture of the tibia or a trashing of the
ACL.
Where there is some sideward motion too I suspect the rear releasable
binding gives adequate protection. I believe you can only protect the
leg
properly and at the same time prevent a binding pre-release by using a
toe
release binding.

Based upon what?

Based on all the above.

What prompted this request for more info is that I know someone who had a
spiral fracture with Silvrettas. Since toe release bindings on alpine skis
were adopted in the 1970s I have seen the incidence of "legs in plaster"
go
from very high down to insignificantly low. A 90% reduction is reported
of
mainly tibia injuries in Sports Med 1999 Jul;28(1):35-48 (ISSN:
0112-1642).

"John Mason" wrote in message ...
Tele, x-country and silvretta type ski touring bindings all appear to be
fixed at the toe and will not allow the foot to release from the toe. I
remember the terrible number of downhill skiers who suffered broken legs
before toe release safety bindings were invented. Are these bindings not
dangerous? If not why do downhill skiers bother with toe release bindings?


The traditional explanation is that free heelers never went that
fast compared to alpine skiers. That does seem to be changing.
In my case I'm pretty deliberate on the resort groomers, but that
raises another safety issue. It seems that an increasing number
of skiers/boarders are inclined to regard someone slower downhill
as a potted plant...who ever hurt themselves cutting too close to
a ficus?

Also, I suspect that having the heel free results in fewer falling
situations where the ski is generating maximum twisting force by
leveraging at a perfect right angle to the leg.

John Reece