The NNN/BC Truth Thread

[Rodbelan]

There ain't no rules in skiing unless you talk to the PSIA instructors

I don't think you have it right. PSIA instructors just developed a certain pedagogy for downhill skiing, for a certain terrain... Most CANSI (like PSIA) instructors that I know are pretty open mind... They know the limits of their teachings... Nobody there have the theory of the «grand tout» (great wholeness)...

Have you followed a class by a certified PSIA instructor? Like everywhere, you might find an individual with a dogmatic mind... That's the exception, not the rule...

[The Lovely Bear]

[Teleman]

Sorry for setting you off on Thanksgiving Connie.....Should be thanking our collective stars for having the time to ski and write about it. This being the day after Thanksgiving.....heh.....Connie I don't really think much about you or your skiing....You seem to be a stalker.....Figure that's your problem....My tip to you is to put on some leathers, pins and skinnies and hope you have an epiphany....Telemark sets you free.....Makes everybody I know grin, laugh....Try real hard connie and you too might get a laugh out of it...TM

[MikeK]

Happy belated Thanksgiving Teleman and connyro.

We do have a lot to be thankful for!

And hey Teleman, I don't know conny all to well, but he's been pretty active on this forum. I'm pretty sure he skis everything from leather and skinnies to fatties and plastic.

I think you and I are the only ones who don't use plastic Although I have an old pair of resort Tele skis I'm going to maybe try this year I'm going to get for a song from another forum. I figure I'll give them a try when there isn't any natural snow. Honestly, I'm really not excited about skiing on-piste. I need to find a cheap (used) pair of plastic boots though.

[lilcliffy]

Mechanically speaking, the 75mm plate has more leverage than 68mm plate of the widest NNN binding for rolling the ski on edge. The wings on the 75mm plate offer more yaw control because there is virtually no slop between the side of the boot and the wings where the NNN relies mainly on the ridges on base plate to accomplish the same task.

I'm afraid I don't buy this...IMO, it is the boot that is offering the leverage- the width of the toe/BAF attachment plate does not increase that leverage...if the toe/BOF attachment is strong enough, all other things being equal, the boot should offer the same amount of leverage- regardless of 75mm or NNNBC (the addition of a heel cable greatly increases both binding resistance and torsional strength). The toe/BOF attachment is not a fulcrum- a skier cannot use the outer extremities of the toe/BOF plate to lever the ski over- the skiers weight is centered on the plate- period.

The lever is not determined by the width of the toe/BOF plate.

The lever is determined by the height of the plate in relation to the ski edge.

The only way to increase mechanical levering advantage is to raise the height of the binding plate in relation to the ski edge.

As an extension of this- taller boots offer much more steering/edging leverage than short boots.

IMO, the main downhill advantage of 75mm for downhill skiing is because you can take steering/edging power way beyond NNNBC and basic 3-pin.

Basic 3-pin and NNNBC bindings are both primarily designed for XC skiing. IMO, serious downhill skiing is taking both of these bindings out to their limits of steering/edging power.

IMO- basic 3-pin or NNNBC? A matter of personal preference- and in particular a matter of finding the ideal boots for backcountry-xcountry skiing.

(I do have more to say about the K&G performance between the two- I am waiting for a response from Rottefella- I will post in the NNNBC thread)

[MikeK]

In terms of ski leverage, it is both the width of the plate AND the height of the binding interface above the edge AND the stiffness of the boot at the ankle (and height).

I can prove the binding width in a number of ways, but the most simple way to convince yourself of this is that Rottefella went through extra effort to tool up and make two different BC bindings, the regular and the magnum. The main difference between them is the plate width where the boot interacts.

Going from 58 to a 68 mm plate on NNN BC provides a similar action as going from a 68mm plate to 75mm pin binding. It's not exactly the same ratio, but it direction all the same. The ball of my foot is 95mm wide, and my boot wider than that. So until we reach that limit there is more leverage available.

Now this only really works if your plate is wider than your edges. If you had a 68mm plate centered on a ski with a 68mm waist, you'd have no lever arm except the height of the binding and the upward pull from the toe bar when the ski was flat (and your cuff to edge lever arm if you have a stiff cuff acting to pull the ski UP ). When the plate is wider the than the waist of the ski, the lever arm here is relatively small, but the force is large because it is directly a result of your body weight, so it can be a significant factor.

Putting 75mm bindings on narrow skis gives a very large amplification, and is why some people really prefer this. You honestly don't need a ton of force to edge the ski, just enough to overcome the slop in the system and get the ski to roll.

Now here's the rub. When you get really wide waisted skis (particularly when the ski is wider than the binding plate) you can't do anything if you don't have a stiff boot that can transmit knee motion. The upward pull from bail is minimal and hard to control, the downward push from body weight actually tries to keep the ski flat! Then your only real option is a stiff boot cuff in which the lever arm becomes large (the cuff of the boot to the edge of the ski) and the force is less. This force actually reacts through the toe bar or the bail, and pushes UP to create a lever arm resisting your weight pushing the ski down.

If you have a cuff, a binding plate that is wider than the ski, a binding interface that is elevated above the edge of the ski (all bindings do, some higher than others), and a bail or toe bar that can react upwards, then all these torques act together to roll the ski on edge. This is why we often say we need less boot power to control a narrower ski, but this of course assumes there is enough leverage in the binding interface to transmit the forces and enough stiffness to transmit the motion.

My personal thought is for the amount you really need to edge some relatively narrow, soft flexing xcd skis, the torque is fairly adequate from the NNN BC plate and a torsionally stiff boot with no cuff. Even if the boot doesn't have a cuff to transmit the force above the ankle, if the sole is torsionally stiff and tight fitting on the ankle (and your ankles are relatively strong) that knee motion gets transmitting to toe using the BOF as a pivot and the toe bar as the torque transmission from the boot to the ski. You can easily feel this on soft 75mm boots as the duckbill twisting. Your knee is actually driving this via your heel motion but the ski is rolling less than your body is moving, hence the wind up in the boot.

There are many forces that you can apply via your boot to your ski, but the binding's stiffness and degrees of freedom will only let you transmit a certain amount of motion from your body to the ski. If you aren't generating high cornering loads (high g corners) and you can compensate for the lack of balance and extra compliance, the ski can be controlled.

Control is relative term though. There's stuff I think about skiing someday with my xc skis that when I think about it, scares me. I'll do it, no doubt, but I know there is hairy, on-the-edge feeling I have that will make it exciting. I could go ski this with alpine gear and I don't think I'd be nervous at all. In fact I don't think it would be hard for most alpine skiers.

[Cannatonic]

interesting discussion, I would still use NNNBC for XC if I had some comfortable boots. But seeing as I found very comfortable 75mm boots, it's easier to just convert the quiver over to 3-pin. The Scandanavians are using nice leathers like Lundhags and Alfa NNNBC boots that we don't see in the US. I'd still take 3-pin all day long for actual telemark skiing.

regarding mounting point, I agree that BP is best for the XC/tele skis with camber, my issue is whether or not to compensate for large foot size. Neptune was saying no, because it's easier to do tele turns at BP with your toe clamped at the mid-point of the ski's weight. They're saying your back foot will drag the tail of the ski during tele-turns if you move the bindings forward. I have a pair of E99 mounted 1cm forward of BP, I doubt it will make a huge difference either way, but I don't want to pierce the Gamme54's until I know for sure!

If you grew up skiing alpine downhill I think ANY nordic or tele setup is going to feel a bit awkward when turning on hardpack. You're in the back seat compared to alpine. With big feet they move your bindings up even farther on alpine skis, but not nordic.

going to be Quebec City over New Year…BG, looks like Rimouski is 3 hours away. Wow, the Chic-Chocs are in your back yard! There must be some great skiing around there. Looks like NB and the Gaspe peninsula are getting slammed with snow right now too. Hopefully I can find somewhere around Quebec City to ski, the group is going to Mt. St. Anne a couple days, maybe I'll try their XC area. Or the Plains of Abraham trails.

[lilcliffy]

I can prove the binding width in a number of ways, but the most simple way to convince yourself of this is that Rottefella went through extra effort to tool up and make two different BC bindings, the regular and the magnum. The main difference between them is the plate width where the boot interacts.

Going from 58 to a 68 mm plate on NNN BC provides a similar action as going from a 68mm plate to 75mm pin binding. It's not exactly the same ratio, but it direction all the same. The ball of my foot is 95mm wide, and my boot wider than that. So until we reach that limit there is more leverage available.

Well- I still don't buy this. Leverage on a ski edge is vertical- not horizontal.

If the boot is securely attached to the binding plate, and the sole of the boot is rigid enough- with respect to leverage, what does it matter how wide the binding plate is?

The binding plate on my alpine bindings is narrower than 75mm- all of the leverage is coming from the high, rigid boot. I increase the leverage by angling my leg towards the ground- a lever in the vertical plane.

The SNS-xadv binding plate is narrower than both the basic NNNBC plate and the 75mm plate- it offers just as much inherent leverage.

The fundamental advantage of the width of the 75mm binding plate is that you can extend the amount of lateral force way beyond NNNBC/SNS-xadv. The width of the 75mm plate will handle the torsional force of much more powerful and rigid boots and cable systems.

The width of the binding plate adds potential strength to the binding- not leverage.

I still don't see the physics of how the width of the plate itself increases leverage.

Please do "prove" it.

[lilcliffy]

Decided to take this down.

[bgregoire]

Cliffy,

is this the new NNN/BC Thruth Thread?

http://www.telemarktalk.com/viewtopic.php?f=1&t=76

Are you sure you want to go down that route?

I did enjoy those nice pics of your Alaska boots!

What about the old BOF discourse? As much as I love NNN BC, 75MM makes me feel like my BOFs are better pressed into the ski as I tele. Plus, the wider range of stiffness in 75MM boots means I can have more boots than skis in my quiver, and hence, quite a world of possibilities!