Physics debate

[DG99]

We determined that the ball of the foot is a fulcrum and the leg is a lever, and you can lever onto the tip of the ski.

[Verskis]

Here is one more experiment. Upper picture has the binding with springs (this could be again substituted with NNN BC with flexor, Xplore with flexor, 3-pin with bending duckbill (the duckbill is a torsional spring)).
Lower picture is exactly the same situation with horizontal force (hand) pushing the boot forward, but the binding is now just the toepiece of a TTS binding (=same as alpine touring tech binding toe part) with very low friction pins as a pivot point. With that binding, you are unable to affect the readings of the scales, as the springless binding does not transmit any torque to the ski.
suksikuva2.png

Thanks to Tom M, we now have the test I described above for everybody to see on Youtube:


Tom even improved it nicely by using a string to pull the boot instead of pushing with the hand, as you could more easily accidentally apply downward force with the pushing hand.

I quite honestly expected very heated discussion here about this video, but saw none, to my surprise.

Based on the test results and according to Grimsurfer physics lessons, Newtonian physics don't seem to apply anymore, as all the forces were supposed to cancel each other...

[Verskis]

3. The mass applied to the front of the ski is the result of pressure provided by the skier’s weight. Nothing else “creates” this mass.

There was one thing I'd like to continue discussing with GS: with freely rotating binding (and without torsionaal spring like boot duckbills), whenever the heel is off the ski, the skier's mass(x gravity = weight) would only be able to produce normal force (perpendicular force to the ski bottom plane) at the pivot point of the binding. The front of the ski (dare I say "tip" anymore?) and the rear of the ski (aka tail) would get the exact same loading, if the ski would be symmetric front to back.
Now with the cables or flexors or duckbills or whatever the spring system is, the skier is able to manipulate the loading of the front part of the ski versus the rear part of the ski. The total force will be the skier's weight even with the cable bindings, but not 50/50 split anymore. This is something we all have been trying to say all the time, and what is confirmed by Tom's excellent video.

[GrimSurfer]

3. The mass applied to the front of the ski is the result of pressure provided by the skier’s weight. Nothing else “creates” this mass.

There was one thing I'd like to continue discussing with GS: with freely rotating binding (and without torsionaal spring like boot duckbills), whenever the heel is off the ski, the skier's mass(x gravity = weight) would only be able to produce normal force (perpendicular force to the ski bottom plane) at the pivot point of the binding. The front of the ski (dare I say "tip" anymore?) and the rear of the ski (aka tail) would get the exact same loading, if the ski would be symmetric front to back.
Now with the cables or flexors or duckbills or whatever the spring system is, the skier is able to manipulate the loading of the front part of the ski versus the rear part of the ski. The total force will be the skier's weight even with the cable bindings, but not 50/50 split anymore. This is something we all have been trying to say all the time, and what is confirmed by Tom's excellent video.

Tom’s test was appropriate for measuring the different flexors. His results yielded comparative data for this.

The method he used was t appropriate for determining weight transfer. Why? Because the vector of force applied by his assistant was wrong… it was 90 degrees from the force exerted by a skier.

People using the video as the basis for talking about tip pressure would be like NHTSA determining frontal crash standards for cars by dropping a test sled on the roof of the car.

Measuring force at one point (ends of skis) provides one data point. If the scales had been placed in various positions along the ski, we could have had some kind of discussion about forces along the length of a ski… provided we kept in mind that issue of the wrong force vectors.

I don’t expect many people to understand, or even accept, this. So I don’t intend to prolong the pain by extrapolating from a test that only achieved one thing: Providing comparative values of different flexors.

[fisheater]

@Tom M Great video and I agree that there isn’t a best system, only a system that works best for that particular skier.
You sure have some beautiful, and just darned nice to ski terrain.
I commend you for staying above the fray. I didn’t and I apologize to the guys that didn’t need to listen to a PO’d rant, when they just wanted to read about skiing.

[DG99]

[
Tom’s test was appropriate for measuring the different flexors. His results yielded comparative data for this.

The method he used was t appropriate for determining weight transfer. Why? Because the vector of force applied by his assistant was wrong… it was 90 degrees from the force exerted by a skier.

People using the video as the basis for talking about tip pressure would be like NHTSA determining frontal crash standards for cars by dropping a test sled on the roof of the car.

Measuring force at one point (ends of skis) provides one data point. If the scales had been placed in various positions along the ski, we could have had some kind of discussion about forces along the length of a ski… provided we kept in mind that issue of the wrong force vectors.

I don’t expect many people to understand, or even accept, this. So I don’t intend to prolong the pain by extrapolating from a test that only achieved one thing: Providing comparative values of different flexors.

I think that’s all he was trying to prove, that force gets applied to the tip, absent weight, and gravity. You didn’t seem to believe that happens. Or maybe that it happens with bumpers and duckbills but not from cables.

And you insult people

[Lhartley]

@Tom M Great video and I agree that there isn’t a best system, only a system that works best for that particular skier.
You sure have some beautiful, and just darned nice to ski terrain.
I commend you for staying above the fray. I didn’t and I apologize to the guys that didn’t need to listen to a PO’d rant, when they just wanted to read about skiing.

It WAS about skiing. And interesting. Except for the Sartre quotes. Zzzzzz. Should measured the cables

[GrimSurfer]

@Tom M Great video and I agree that there isn’t a best system, only a system that works best for that particular skier.
You sure have some beautiful, and just darned nice to ski terrain.
I commend you for staying above the fray. I didn’t and I apologize to the guys that didn’t need to listen to a PO’d rant, when they just wanted to read about skiing.

It WAS about skiing. And interesting. Except for the Sartre quotes. Zzzzzz. Should measured the cables

It’s one of those subjects, I suppose, that holds great interest to some while angering others.

Regardless, there is some value to be derived from thinking about what we’re doing (or trying to do) well.

As for calls to OT a thread dedicated to the dynamics of skiing, I’m not sure what this says when other topics in the “Telemark Talk Forum” include beer, candle making, cabins in the woods etc.

[Stephen]

After 37 pages, why is anyone still trying to convince the other side that something does or doesn’t happen?

This is like the Middle East Arab / Israeli conflict, or the Cold War, or Trump or not Trump. Endless. No winners.
People believe what they believe, and few change their mind.

No one needs saving, here.
I mean, in a way, it’s entertaining, but…

I get the impulse to set someone straight, get them to see the light.
But it ain’t happening.

I’m tempered.
Well so and so, in what direction should the puppeteer pull the string to prove you’re right?
But more input just feeds the machine.

[Verskis]

3. The mass applied to the front of the ski is the result of pressure provided by the skier’s weight. Nothing else “creates” this mass.

There was one thing I'd like to continue discussing with GS: with freely rotating binding (and without torsionaal spring like boot duckbills), whenever the heel is off the ski, the skier's mass(x gravity = weight) would only be able to produce normal force (perpendicular force to the ski bottom plane) at the pivot point of the binding. The front of the ski (dare I say "tip" anymore?) and the rear of the ski (aka tail) would get the exact same loading, if the ski would be symmetric front to back.
Now with the cables or flexors or duckbills or whatever the spring system is, the skier is able to manipulate the loading of the front part of the ski versus the rear part of the ski. The total force will be the skier's weight even with the cable bindings, but not 50/50 split anymore. This is something we all have been trying to say all the time, and what is confirmed by Tom's excellent video.

Tom’s test was appropriate for measuring the different flexors. His results yielded comparative data for this.

The method he used was t appropriate for determining weight transfer. Why? Because the vector of force applied by his assistant was wrong… it was 90 degrees from the force exerted by a skier.

People using the video as the basis for talking about tip pressure would be like NHTSA determining frontal crash standards for cars by dropping a test sled on the roof of the car.

Measuring force at one point (ends of skis) provides one data point. If the scales had been placed in various positions along the ski, we could have had some kind of discussion about forces along the length of a ski… provided we kept in mind that issue of the wrong force vectors.

I don’t expect many people to understand, or even accept, this. So I don’t intend to prolong the pain by extrapolating from a test that only achieved one thing: Providing comparative values of different flexors.

The video proves that the boot-binding-ski combination can be used as a lever to pressure the front of the ski, which you have been denying all the time.

But I see the point of Stephen, let's leave the physics-heretic without the enlightenment