Another Pavel Tip: Plastic ski plates and screws

Most if not all top level skis have some type of plates on which bindings are screwed on!

There are many types of plates and companies do all sorts of things to "reduce " ski weight! I have noticed in the passed two years that many plates are NOT solid rubber or plastic but rather "hollow" in some sections or thinner!

After every day testing skis,,I always check screws by hand! I have noticed that many need some tightning after heavy use! In two cases the screws would not tighten! Seems the technician had used a drill and "stripped" threads ON PLASTIC!!
Very dangerous!!!!

We had to install heli-coils inserts in order to get firm grip! I then called some technicians who service world class racers and they all told me that all top level racers have heli-coil inserts!

I do not expect you to insist on having helicoils put in ( since few people know how to do this),,however I am suggesting that if you ski hard,,,check binding screws every two weeks!
It might save you an "accident"

Ho....as Ise would say, "if you are not a certified technician" do not play with screws!

However if you can handle a posidrive screwdriver and know what a tight screw feels like,,go ahead check them! I am sure you will find some loose!
I always do!!!

Pav, thanks for the tip.

Have you seen or done any test on the effectiveness of plate and binding systems to allow the ski to flex naturally. Seems when I'm in a store flexing skis from the rack, I see some plates still seem to create a flat spot on the ski, despite all the innovations to prevent this.

Trencher


Atomics seem to flex evenly

First Trencher,,is that your picture! If so great carve!!!

Your observations are very correct!
Some plates are more for "look" that function!

Of course the very best are VIST plates and this Italian company produces 80% of plates for other companies!

In my opinion the "superior" plates all have at least two plates for front and back!
The Rossis have three hinged units with a tuning option for each articulated section! very effective and very costly!

The Fischers are also great plates since they allow great flex with slotted screws and a metal shank connecting rear and frint units! In the center are two springs which can be locked or allow to play free!

Head has same system!

Most skiers who ski "relaxed" techniques do not really feel the difference,,however in fast hard radical carving turns you really do feel the difference!

Keep of carving Trencher!

pavelski wrote:First Trencher,,is that your picture!

My Metron M9s (old model) take some beating for carving it up.

I wish I had the opportunity to play with more types of skis. I think that the modern trend to wider waist in skis negates much of the need for riser plates and perhaps damping could be addressed in the binding and it's mounting. The talk about the extra leverage offered by riser plates doesn't make sense to me either. What difference does a few mm make when one skier might be 200mm taller than the next.

One thing is for sure, big riser plates make you look very serious 8).

Trencher

Trencher wrote:

pavelski wrote:

One thing is for sure, big riser plates make you look very serious 8).

Trencher

They can also do some serious damage to your knees over time! It takes very little extra height to radically increase the forces at work on your ligaments :D

Macski wrote:
They can also do some serious damage to your knees over time! It takes very little extra height to radically increase the forces at work on your ligaments :D

That makes sense. I guess a 25mm riser would increase the leaverage on the knee by about 5% (Dave Mac, is that right ?)


Trencher

Trencher, I don't know if you're going to enjoy this, I'm sure that some people will lose the will to live. I think I have the following right, but if anyone can do better, let us here it.

Firstly, I don't know what a riser is, but from what you say, it must raise the fulcrum that the boot operates on.

So here goes. I am using my body measurements, but they will ratio to other heights. I am 6' 2" tall.

Data & Assumptions:

For skiing dynamics, the body momentum passes through at the metacentric height. On the human body, the MH is at the centre of the chest. Height to my solar plexus is 1400mm. With a riser, MH would be 1425.

Height to centre of my knee, with boots on is 575mm. With a riser, knee height is 600.

So you hit a bump, the body momentum (F) is forward, there is an opposite force (f) on the knee.

So without a riser, we have F1 and f1. With a riser, we have F2 and f2.

Using the principle of leverages,

No riser, 1400 x F1 = 575 x f1, With riser, 1425 x F2 = 600 x f2

So, F1 = (575/1400) x f1 and F2 = (600/1425) x f2

but F1 = F2

Hence (575/1400) x f1 = (600/1425) x f2

And, change in knee force f2/f1 = (575/1400)/(600/1425)

= 0.975

This indicates that in the riser condition, there is 2.5% less force on the knee.

It may be that the fulcrum should be measured from the bottom of the ski. (I'm not going to do that, I am already in my dressing gown, wearing ski boots and a tape measure, desperately hoping that my OH doesn't come into the room.)

However, in that case, the force on the knee would be even less.

It may also be that in using a riser, the fulcrum remains as the base of the boot, actually at the toepoint. In which case, there would be no change in knee leverage.

Simple innit?

Forgot to say, great picture, beautiful technique. I'm not a carving fan, but when it's done as well as that .....