The Numbers Game: Bindings, Part 2

[Mike Thomas]

It's just when I looked at it, I thought it was broken because it assumes a weight range for a height range. I would think...

Don't think. That's not at all how it works.

Seriously, this is where a little knowledge gets dangerous. The chart is designed to estimate bone density based on body size. It isn't perfect, but it works pretty darn well. If height and weight ranges do NOT fall on the same line of the chart, you move UP the chart to the parameter that 'works'. What I mean is, if the skier is 5'4" and 250lbs, you read along the 5'4" line on the chart. If the skier is 6'3" and 150 lbs you read along the 150 lbs line. You always move UP never DOWN.

And folks, if you don't like the over 50 bit or how the chart 'works'... lie. As a tech, I don't give a flying F if you lie to me, just don't put me in a situation where I am liable. I'm not going to check your ID or make you step on a scale... but why not let me test the binding function set 'right' and then YOU set it wherever your little heart desires. By yourself. That way we are all happy (and at least I am safe).

 

[PisteOff]

Don't think. That's not at all how it works.

Seriously, this is where a little knowledge gets dangerous. The chart is designed to estimate bone density based on body size. It isn't perfect, but it works pretty darn well. If height and weight ranges do NOT fall on the same line of the chart, you move UP the chart to the parameter that 'works'. What I mean is, if the skier is 5'4" and 250lbs, you read along the 5'4" line on the chart. If the skier is 6'3" and 150 lbs you read along the 150 lbs line. You always move UP never DOWN.

And folks, if you don't like the over 50 bit or how the chart 'works'... lie. As a tech, I don't give a flying F if you lie to me, just don't put me in a situation where I am liable. I'm not going to check your ID or make you step on a scale... but why not let me test the binding function set 'right' and then YOU set it wherever your little heart desires. By yourself. That way we are all happy (and at least I am safe).

I have my guy set them to the chart and then I put them where I want them. I completely agree with you. The main thing is knowing that the binding does release properly.

 

[BC.]

Child Setting Indicator Value?

My kids are:

5 year old 228mm sole length and he weights 50lbs according to the chart setting would be 1.75

8 year old 230mm sole length and she weighs 60lbs according to the chart setting would be 2

Is this correct, I thought I read once on a Salomon data sheet that for kids and adults over 50 years old you derate 1 position?

9 and under
50 and over

Yes....you are getting a setting “back” up the said “chart”.

Yes....it pisses most 50+ year olds off....but it is what it is. You don’t like it...change it yourself to your desired setting. Just know, my “ski tech sign off paperwork” is now void.

 

[Philpug]

9 and under
50 and over

Yes....you are getting a setting “back” up the said “chart”.

Yes....it pisses most 50+ year olds off....but it is what it is. You don’t like it...change it yourself to your desired setting. Just know, my “ski tech sign off paperwork” is now void.

I am 49...and 48 months.

 

[John O]

Forget the analogies. Just learn something about bindings. You're trying to go off very little information of a general description on a binding website. You're making all sorts of confirmation leaps. There's a difference between being "OK" and having a binding that drives the ski well. No one said you're in danger.

That's a little condescending. LegacyGT is doing exactly that in this thread... asking questions and trying to learn.

@LegacyGT This is a case where if you have to ask, buy the cheaper binding. There is no performance advantage to the better binding. For the person with a 12 DIN, their choice of a 16, 18, or 20 spring binding has nothing to do with their DIN setting.

That's also condescending. There's no correlation whatsoever between someone's knowledge about the technical workings of bindings and the physics behind it, and their needs on the slopes as a skier. If someone doesn't understand the physics and isn't willing to accept vague generalizations like "it's just beefier", then they must be a bad skier? Come on.

I think LegacyGT was asking some very legitimate questions, and didn't get any real concrete answers.

 

[murphysf]

9 and under
50 and over

Yes....you are getting a setting “back” up the said “chart”.

Yes....it pisses most 50+ year olds off....but it is what it is. You don’t like it...change it yourself to your desired setting. Just know, my “ski tech sign off paperwork” is now void.

thanks thats what I thought as read in the past so for under 9, 2 would become 1.75 and 1.75 would become 1.25.

I always find this confusing because the top part of the chart is for children and junior which are people under 9 so why don't they just put the correct value. I guess maybe that would make it more confusing as what if a 9 or 10 year old and the same weight and sole length as an 8 year old... I noticed that in the chart in the original post there were no footnotes to go up the chart for under 9 and over 50.

 

[BGreen]

@John O It isn’t condescending, it’s honest advice. @LegacyGT ‘s description of his skiing style and the fact that he can easily stay in a binding on a 6 DIN setting tells me that he is not skiing in a way that stresses a binding. Going with a binding with metal construction and heavy springs will do nothing for him aside from removing weight from his wallet and adding weight to his skis. If he were buying light bindings and wearing them out halfway through a season, he wouldn’t be asking the question about why a heavier duty binding is necessary. If he was having frequent pre-releases because his bindings can’t handle flex cycles (vibration, chattering, bouncing), or can’t recenter properly, or if he needed the highest level of power transfer, he wouldn’t be asking the question. He’s not asking if he can get away with a junior binding (I don’t think), but just asking if there is any reason a skier like him would reap any benefit with a top end binding or if it is just upselling. If he were wearing out or breaking his lower end bindings, he wouldn’t ask the question. Since that isn’t happening, then IMO pushing him to a higher end binding is upselling. A Ford F-350 is a heavier duty truck than a Ford F-150, but that doesn’t make it better for everyone.

I wasn’t trying to be condescending, I was trying to avoid having to write this post, which is somewhat condescending.

 

[John O]

@BGreen, for what it's worth, I think that explanation makes tons of sense and is very reasonable. The "if you have to ask, buy the cheaper binding" phrasing is what bugged me. Because one reason someone might have to ask is because they simply don't know. Perhaps they would benefit from a higher end binding but don't know what benefits those bindings bring to the table. Therefore, they gotta ask.

 

[Philpug]

@John O It isn’t condescending, it’s honest advice. @LegacyGT ‘s description of his skiing style and the fact that he can easily stay in a binding on a 6 DIN setting tells me that he is not skiing in a way that stresses a binding. Going with a binding with metal construction and heavy springs will do nothing for him aside from removing weight from his wallet and adding weight to his skis. If he were buying light bindings and wearing them out halfway through a season, he wouldn’t be asking the question about why a heavier duty binding is necessary. If he was having frequent pre-releases because his bindings can’t handle flex cycles (vibration, chattering, bouncing), or can’t recenter properly, or if he needed the highest level of power transfer, he wouldn’t be asking the question. He’s not asking if he can get away with a junior binding (I don’t think), but just asking if there is any reason a skier like him would reap any benefit with a top end binding or if it is just upselling. If he were wearing out or breaking his lower end bindings, he wouldn’t ask the question. Since that isn’t happening, then IMO pushing him to a higher end binding is upselling. A Ford F-350 is a heavier duty truck than a Ford F-150, but that doesn’t make it better for everyone.

I wasn’t trying to be condescending, I was trying to avoid having to write this post, which is somewhat condescending.

@BGreen, for what it's worth, I think that explanation makes tons of sense and is very reasonable. The "if you have to ask, buy the cheaper binding" phrasing is what bugged me. Because one reason someone might have to ask is because they simply don't know. Perhaps they would benefit from a higher end binding but don't know what benefits those bindings bring to the table. Therefore, they gotta ask.

IMHO, the application still needs to be taken into account. I still see many people out of the hill with 100mm plus skis with Salomon Z12's on them and I am sorry, these bindings were never designed to be on skis that wide. @KingGrump can attest to even light weight women compromising these bindings and neutering the perforance of the skis. I don't subscribe to the "if you have to ask.." thought process here because it isn't that simple or black and white of a question but a question that will usually need two or three follow up questions to what is the best binding for an application.

 

[BGreen]

@BGreen, The "if you have to ask, buy the cheaper binding" phrasing is what bugged me.

I apologize to @LegacyGT . It seemed like a more concise way to offer the same advice. My race skis are all Marker 18 or 20 springs. My powder or all mountain skis have Marker Jesters because I’m not a particularly aggressive skier and don’t need the kind of binding that a lot of people on here use who spend their days launching off of cliffs and jumping everything in sight. Also, just being honest, they don’t see that much use.

 

[François Pugh]

I am 49...and 48 months.

I'm 18, with 40 years experience at it.

 

[Atomicman]

That's because I bought a pair: FF17 plus with diagonal heel release.

It's the same with tires; I used to find a tire in my size that was good, then try to replace it with same, which seldom worked (exception being the Michelin Pilots).

I am all about MIchelin Pilots. I have Pilot A/S 3+ on my '11 S4. Unbelievably great wet road tire and wears like iron!

 

[cantunamunch]

I'm 18, with 40 years experience at it.

Don't forget though, only perfect practice makes perfect

 

[Atomicman]

Don't think. That's not at all how it works.

Seriously, this is where a little knowledge gets dangerous. The chart is designed to estimate bone density based on body size. It isn't perfect, but it works pretty darn well. If height and weight ranges do NOT fall on the same line of the chart, you move UP the chart to the parameter that 'works'. What I mean is, if the skier is 5'4" and 250lbs, you read along the 5'4" line on the chart. If the skier is 6'3" and 150 lbs you read along the 150 lbs line. You always move UP never DOWN.

And folks, if you don't like the over 50 bit or how the chart 'works'... lie. As a tech, I don't give a flying F if you lie to me, just don't put me in a situation where I am liable. I'm not going to check your ID or make you step on a scale... but why not let me test the binding function set 'right' and then YOU set it wherever your little heart desires. By yourself. That way we are all happy (and at least I am safe).

it depends on how you define up and down...or what is, is? And yes you move down, oh wait, I mean up.....for skier Type!

 

[markojp]

The correct indicator setting for a skier assumes they have the correct forward pressure set on their binding for their BSL. What if the effective BSL changes? Can it or the forward pressure change enough to affect the indicator setting if one has numerous punches to the toe area of a boot?

You can punch the toe all you want so long as it doesn't interfere with the boot binding interface. You aren't changing the boot BSL at all. Someone puts their 28.5 foot in a 316 (31.6cm) BSL boot. They punch the toe 3-4mm for some room. The BSL is still 316 even if the 'foot container' is now a bit longer.

 

[Bruno Schull]

Hi.

I'm hoping some experts can help me understand something. It seems that, as boot sole length increases, DIN values decreas (I understand that using the word DIN might not be the best terminology, but I'm just going to go with what seems like the most common usage in the industry). Anyway, so as boots sizes get bigger, DIN goes down, assuming everything else stays the same. Why?

For example, I wear big boots, 31.5 or 32 Mondo. And my DIN values are in the 6-7 range, despite the fact that I am 6'4" and weigh 200 pounds, and fairly competent skier on and off piste. I set my bindings in this range, and I basically never have pre-releases, or at least any that I recognize, and the skis come off my feet when needed. I don't think this is because I am a particularly smooth skier (hardly) but just because of the way the system works.

So, how can I envision this as a simple system with forces, levers, fulcrums, and so on? One thing thing might help me in knowing how the testing equipment works. On the test machine, is the ski clamped, or the boot? Where is the force applied?

Is it correct to imagine that, for a sideways toe release, a point under your heel is where your boot rotates? If this is true, why does the DIN decrease with boot size? It would seem that as the boot gets bigger and the distance between the heel and the toe grows larger there would be a longer level arm between the heel and toe, and that the DIN would need to increase to manage the correspondingly higher forces.

I know I'm just thinking about something in reverse or incorrectly. Can anybody help?

(I do realize that all the forces on a ski and boot are complex; sideways, up and down, rotation, purely lateral, all possible combinations, and so on...just to simplify I'm trying to limit this to a sideways toe release, if this simplification is even possible.)

Thanks.

 

[pchewn]

Hi.

I'm hoping some experts can help me understand something. It seems that, as boot sole length increases, DIN values decreas (I understand that using the word DIN might not be the best terminology, but I'm just going to go with what seems like the most common usage in the industry). Anyway, so as boots sizes get bigger, DIN goes down, assuming everything else stays the same. Why?

BSL=500 (unreasonably large) has twice the moment arm as a BSL=250. Therefore, to get the same torque, the force (heel or toe) will have to be 2X as much on the BSL=250

It's math.

Torque = Lever arm distance X force Torque is what breaks the leg. Therefore, if you want the same torque you need to change the DIN setting (force) for changes in moment arm (BSL). Like this:

Let's say you want 50 N-m of torque for the release point for your toe setting.
For a 250mm (.25m) BSL. Your binding will be set at 200N 50N-m = .25m X 200N and that is approximately DIN 6.5

For a 500mm (.5m) BSL. Your binding will be set at 100N 50N-m = .5m X 100N and that is approximately DIN 3.25

 

[Bruno Schull]

Thanks pchewn. I think I understand the math--what I'm having trouble imagining is how are the parts of this system are related spatially. To stay with physics, how would we draw this as a vector diagram? Where is the force applied? Where is the pivot point, or fulcrum? Thanks again.

 

[cantunamunch]

Hi.

Is it correct to imagine that, for a sideways toe release, a point under your heel is where your boot rotates?

Nope, directly under your tibia.

If this is true, why does the DIN decrease with boot size? It would seem that as the boot gets bigger and the distance between the heel and the toe grows larger there would be a longer level arm between the heel and toe,

Yup, you're good so far.

and that the DIN would need to increase to manage the correspondingly higher forces.

And that's where you go awry.

I know I'm just thinking about something in reverse or incorrectly. Can anybody help?

You just need to make one correction. It's not about the force you apply to the snow.

It's about the ground/snow reaction force that can act in opposition to a move you make. The longer the lever arm, the easier it is for such a reaction force to break your bones. Your big foot is giving external forces (in this case reaction forces) a bigger lever to crack things with.

For the purposes of your simplified toe release scenario, visualise a lateral force applied a foot in front of the binding.

So, how can I envision this as a simple system with forces, levers, fulcrums, and so on? One thing thing might help me in knowing how the testing equipment works. On the test machine, is the ski clamped, or the boot? Where is the force applied?

@mdf linked to some standards above, if you find preview versions of those they will include simplified diagrams. They're not going to help you with the mistake above, though, because what is being tested by test machines is the reaction force to what is attempted to be prevented in real life.

 

[PisteOff]

SO, I just had some bindings mounted on a pair of DPS Wailers this weekend. As always, I have the bindings preset to 7 because that's where he is going to put them. He checks them, chuckles. I brought up the debate here on PugSki. He says basically the same thing as Phil. There is no definitive chart. He puts the info into his Wintersteiger machine and runs the bindings through their paces. There is a Nm release value on the screen. The actual value is recorded and needs to be within a percentage range. When he was done he smiled and handed me the test results printout, and the screwdriver........ He knows I am going to set them to 9.