Bindings and broken legs

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?

-----BEGIN PGP SIGNED MESSAGE-----

In article ,
John Mason wrote:
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.

_ Well, this is just not true about the Silvretta[1] and you can get
releaseable telebindings if you want. Karhu 7tm is probably the
best of the lot these days.

I
remember the terrible number of downhill skiers who suffered broken legs
before toe release safety bindings were invented.

_ It wasn't that many, probably far less than the number who now
trash their ACL's. A spiral fracture is not a pretty thing
though.

Are these bindings not
dangerous?

_ Skiing is dangerous. In practice and in the one study I've
seen releasablity doesn't have a significant impact on injury
rate or severity for telemark skiers. Google for tuggy and
telemark if you want to read the results yourself.

If not why do downhill skiers bother with toe release bindings?

_ Because they don't have to carry the weight uphill. For fixed
heel bindings a sideways torque release makes a lot of sense. I
think it makes some sense for telemark bindings with stiff
plastic boots, but I don't worry about it as much as I used to.
Even with stiff plastic boots and beefy telemark bindings, a
free heel allows a lot more give in most situations.

_ Booker C. Bense

[1]- It's not obvious, but the binding actually releases sideways
at the heel which is equivalent to releasing sideways at the
toe.

-----BEGIN PGP SIGNATURE-----
Version: 2.6.2

iQCVAwUBP+kl92TWTAjn5N/lAQHaWwP9EfR264v+jeQMTTDdkR5b1XJb/Lv4Px2W
OT3ZHlC3vY3pDJaMh/Nwk9QSbY63Lje5hVn/QdIkPDZUkeBQjcmNJ1xP9cfEnKrK
TLRU8F8KFkvI3vF3aIQXeX3ep2/u6qsbwAqAs6pfnOZyFzAvSx+6YXgeMXDlMU/t
W0kyYo5rwQ4=
=WcLB
-----END PGP SIGNATURE-----

I can't speak to the tele binding issue, but I have both Silvretta &
Tourlite bindings on my AT rigs and both have boot release in two
directions: for a forward fall they release at the heel, and for a twisting
fall they release under the foot (popping out at the heel & toe). Poorly
described, but suffice to say that they release in both directions just like
downhill gear. Indeed, I've experienced both kinds of falls on AT gear with
perfect release characteristics.



"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?

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.

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). 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.

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. 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.


"Frank Wiles" wrote in message
...
I can't speak to the tele binding issue, but I have both Silvretta &
Tourlite bindings on my AT rigs and both have boot release in two
directions: for a forward fall they release at the heel, and for a
twisting
fall they release under the foot (popping out at the heel & toe). Poorly
described, but suffice to say that they release in both directions just
like
downhill gear. Indeed, I've experienced both kinds of falls on AT gear
with
perfect release characteristics.



"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?

Bob Lee wrote:
There have been times when I was glad my tele bindings didn't release,
and I have never seriously wished they would have...but I've never been
caught in an avalanche knock wood.

They'll come off in a slide. The question is how much of you they take
with them.

-klaus

"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.

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.

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.

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?

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?

Cheers,
Frank

"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).

-----BEGIN PGP SIGNED MESSAGE-----

In article ,
John Mason wrote:


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).


_ I think it's very dubious to claim that "toe release" is the
only reason for this. Toe release bindings were in common use
long before the broken leg injury rate dropped. There's a lot
of engineering and standards in todays's Alpine bindings that
just aren't there in ANY AT binding[1]. The injury rate really
didn't drop until the industry got a really good boot standard
and engineers could make valid assumptions about forces due
to friction at the boot/binding interface.

_ While the silvretta may be "less safe" than other AT bindings,
there's no data that I know of to back up that claim and none of
the "arguments" I've seen on this list[2] make any sense to my
understanding of the physics involved in an injury. It's
definitely less safe than currently available alpine bindings,
but all AT bindings are less safe than Alpine bindings.

_ The Silvretta design has a very long track record, it may
be that it's design is not up to the very beefy stiff AT
boots that are being manufactured these days. After all,
it was the arrival of stiff high plastic boots in the 60's
and 70's that drove the current alpine binding to it's rather
excellent safety standard. Maybe something similar will
happen with AT.

_ Booker C. Bense

[1]- If they were AT bindings would weigh twice as much as they
currently do or cost twice as much.

[2]- Check googles groups archive for the long debate we had
about this very issue this summer.

-----BEGIN PGP SIGNATURE-----
Version: 2.6.2

iQCVAwUBP+3AVWTWTAjn5N/lAQFxqwQAkzzKhhZKIeVyQdydJB9FyiLcMrwR70ZJ
YXzdEaB47ydze7cKkmmnHjzWVbccdI2oaUK3X/ZhxdTPSQmfcurRJKIeGHvaa/03
gLYElpdT6Av2ydDoy21Pfqiqt3/yF1+UBwll1MJ9UR0NlM61m9aIuCwOkrk+gQs0
D3dF/fDGwQ8=
=ct3W
-----END PGP SIGNATURE-----

lac.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.