NNN BC - faith somewhat shaken

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Jurassien
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NNN BC - faith somewhat shaken

Post by Jurassien » Sat May 27, 2023 7:59 pm

I have been using the NNN BC boot/binding system since the early 90s and, apart from one of the original bindings (the version on which the lever was a metal ring) breaking, I have never had cause to complain. The system convinced me because of its lightness, simplicity and reliability and I currently have it on four ski-sets.

Last season (April, 2022) I had my first serious failure, when a boot sole separated from the upper in the middle of a long tour. I was lucky with the outcome, but the breakage was cause for concern (especially as the boot was relatively new) and brought me to this forum looking for a “get-you-home” solution. It was the subject of my first post on the forum. No photos could be provided, as the defective boot and its partner had to be scrapped en route:

https://www.telemarktalk.com/viewtopic. ... 256#p50256

This past season (March, 2023) I was hit again, this time by a binding failure. Again, in terms of personal safety, I was lucky with the outcome, but nonetheless had to break off the tour, fly back to Switzerland from Norway, and return later with different skis. The breakage occurred after I had left a serviced hut in the Skarvheimen mountain range, heading for a self-service hut a mere 12km to the north-east. After travelling for circa 9km my left foot suddenly came out of the binding. On inspecting the binding I was bewildered at first, then caught sight of a piece of red metal lying on the surface of the snow just behind me. The clamp “claw” which engages with the toebar on the boot had shorn off completely, rendering the binding irreparable. Luckily, the weather was stable and the very strong winds of the previous days had compacted the snow surface to such an extent that I was able to carry the skis and walk the 9km back to the serviced hut without difficulty.
NNN BC pair.JPG
NNN BC break.JPG
On mulling over what could have caused such a breakage, I remembered that I had recently sprayed the bindings with WD-40 – using the lithium variant for the first time, instead of the standard WD-40 which I normally use. I also remembered having frost blisters from previous experiences with various aerosols in different situations, when I neglected to wear gloves. The thought occurred to me that I might have “shocked” the metal by spraying too much or too close. I then made a little non-scientific experiment by placing a thermometer on a table, on a warm late-spring afternoon, and spraying it at close range with the same lithium WD-40. The result was, as expected, a drop in temperature, but the difference was far more than I could have imagined. The thermometer happily displayed just over 28°C (82.4°F) before being assaulted by the spray but sank very rapidly to minus 25°C (minus 13°F) on being sprayed.
Plus 28.JPG
Minus 25.JPG
I have no academic background in science and can’t claim the above experiment to give a definitive result, but I can’t help thinking that the metal could have been weakened by such a rapid temperature shock. I will continue to lubricate the NNN BC bindings in future, but without spraying directly.

EDIT: I have since repeated the above experiment at ambient temperature of 27° C (80.6° F) using standard WD-40 from an aerosol can. Result: When sprayed directly on the bulb of the thermometer there was no significant drop in temperature. It seems that the propellant in the lithium WD-40 causes the deep-freezing but the standard WD-40 does not.

In fairness, it should be stated that the bindings were old. On the plastic housing inside there is a little disc which can be seen on lifting the lever. This shows the year and month of manufacture which, in this case, was March 2006. I bought and mounted the bindings about two years after that and they are on skis which have a (documented) 1500km on the clock, as well as a very considerable distance before I started documenting with GPS. I’ve certainly had my money’s worth, but, in the case of ski bindings I imagine most users would take the “If it ain’t broke, don’t fix it” attitude as opposed to “these bindings have been on the skis for xx years, so it’s time to take them off and replace with an identical pair”. The age of the binding/ski should also be seen relative to the number of skis I have (i.e. a lot!) - so some skis get used only a little or not at all during a season.

I have fortunately been spared the toebar-pulling-out-of-the-boot breakage which has been documented elsewhere, but those reports, together with the two failures described above, have somewhat shaken my faith in the NNN BC system. I consider the 75mm system, while not failure-proof, to be easier to deal with if something goes wrong, and from the conversations I’ve had with several Norwegian ski-tourists it seems I’m not alone in thinking this. I’ve become enamoured of the Rottefella 75mm with Cable, having tested it on the piste as well as on 160km of mountain touring this season, and now have it mounted on three pairs of skis. I’m aware that bails can pop off and that 75mm soles can (certainly) delaminate, but the cable/3-pin system has a certain redundancy in the design as well as being definitely superior to NNN BC in terms of purely downhill performance. Apart from the three ski-sets mentioned, I have stocked up with 75mm boots (six pairs, no less!!!). I welcome the new Xplore system, but wouldn’t seriously consider using it till it has been tried and tested over several seasons.
Last edited by Jurassien on Fri Jun 02, 2023 3:11 am, edited 1 time in total.

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Manney
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Re: NNN BC - faith somewhat shaken

Post by Manney » Sat May 27, 2023 8:29 pm

Thought those bindings looked old. Haven’t seen the red clamps in years… all plain steel now.

Cold shocking metal doesn’t normally result in embrittlement. That usually happens when steel is heated until it glows and rapidly quenched. A ~100 degree F change won’t do that to steel… pot metal casting maybe, but not steel. Besides, the steel composition used in ski bindings could be expected to have good strength down to at least -40 to -60F… skiing being a cold weather sport.

The breakage looks more like a fatigue failure… rough edges, not cleanly snapped as would happen with embrittlement. Maybe some pitting from corrosion. Not a professional diagnosis tho… hard to come to any firm conclusions with 1-2 photos.

16 years and a lot of miles. You should be proud of yourself. Lots of memories, not counting a messed up session.
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Re: NNN BC - faith somewhat shaken

Post by Stephen » Sun May 28, 2023 1:24 pm

If you are able to disassemble the unbroken binding and examine the corresponding piece, that might give you some clues. Would the unbroken one easily break in the same place?
It could come down to a defective piece of metal, or a serious stress sometime in the past.
Neither of which provide a conclusive answer.

For any trip to remote areas, it seems a simple solution would be to replace any bindings with significant distance and, or age.
That should give inexpensive peace of mind?
Alternatively, carry one spare binding?
But I imagine you’ve had both those thoughts, or would just switch to 75mm.



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Manney
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Re: NNN BC - faith somewhat shaken

Post by Manney » Sun May 28, 2023 3:38 pm

Sounds right. The stress might be from trying to close the binding when the toe bar is fouled with snow. Happens all the time.

Agree with periodic replacement… like periodic tire replacement before a epic road trip.
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Re: NNN BC - faith somewhat shaken

Post by fgd135 » Mon May 29, 2023 10:48 am

Carrying a spare binding and a screwdriver is always a good idea on long tours.
I also had a boot sole rip off when using an NNN binding, but it was with classic racing boots on a pr of Fischer RCS skis, not in the backcountry. The sole came clean off the upper, and stayed in the binding. Had a good laugh! , but I was only a km or so from the nordic center lodge. Having the same thing happen in the backcountry would not have been funny.
Unlike replacing a broken binding, I'm not sure that a boot damaged like that could've been made to work well enough to ski out.
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Re: NNN BC - faith somewhat shaken

Post by spopepro » Tue May 30, 2023 6:07 pm

The most recent failure reminds me of a post on a cycling forum from many years ago. Someone was complaining about their Chris King headset biting the dust... after like 100,000km. Sure, you expect tried and true designs to last for a very long time... but none of this stuff is forever. I think you might have just found the EOL of NNNBC. 99.9% of users won't ever sniff it--but you should make inspection/replacement part of your routine.



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Re: NNN BC - faith somewhat shaken

Post by Manney » Tue May 30, 2023 6:23 pm

Maybe this is a good time to talk lubrication…

WD40 is a penetrating oil. It is nothing more than kerosine. Like silicone, great for cleaning, driving out moisture. When the carrier evaporates, what’s left behind has no film strength. Doesn’t reduce friction in any meaningful way.

Lithium is a load-bearing metal based lubricant. Its base doesn’t evaporate. Isn’t prone to “drop out”, where the lithium falls out of solution with the “soap”. The soap (the white stuff) holds it in place without evaporating. The lithium complex reduces friction between surfaces. Water resistant. Great general purpose lubricant… probably ideal for ski bindings.

Graphite is a carbon based dry lubricant, contained in a carrier that evaporates. Unlike WD40, it can handle load… has film strength. Messy as AF though. A pain to clean… gets gummy unless it is paired with a soap base… not typical of spray graphite though. Mostly used for car door locks etc. which don’t see frequent maintenance.

Molybdenum disulphide (aka moly, not to be confused with the recreational drug) lubes are at the far end of the spectrum. Another metal based lubricant it typically in a very heavy concentration, soap. Thickens in the cold but a great high pressure lubricant.
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Jurassien
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Re: NNN BC - faith somewhat shaken

Post by Jurassien » Wed May 31, 2023 7:36 am

spopepro wrote:
Tue May 30, 2023 6:07 pm
The most recent failure reminds me of a post on a cycling forum from many years ago. Someone was complaining about their Chris King headset biting the dust... after like 100,000km. Sure, you expect tried and true designs to last for a very long time... but none of this stuff is forever. I think you might have just found the EOL of NNNBC. 99.9% of users won't ever sniff it--but you should make inspection/replacement part of your routine.

I’m not complaining about stuff breaking – especially after a long service life. Most materials which are subject to stress will fail sooner or later. My main concern is what options are open to me if and when equipment fails in adverse conditions. I couldn’t care a rat’s arse if stuff breaks in my native Jura, as in a relatively short time I could get down to a major road/rail artery, make my way home and come back another day. On a multi-day tour with correspondingly heavy rucksack and in remote terrain other considerations apply.

The NNN BC seems to be an “All or Nothing” system – either it’s working as it should or it’s unusable and I have a sneaking suspicion that the Xplore system could be the same. The 3-pin cable, on the other hand, offers you some flexibility in event of failure. If the cable fails the pins will still hold you in (unlike a cable binding without pins). If the bail flies off you have those two slots on both sides of the wings through which you can thread a strap and cinch down the boot while the cable holds from behind. This would at least allow you to limp back to safety. As well as that, the 75mm Vibram-soled boot allows you to walk for considerable distances on gravelled/tarred roads (as I’ve often had to do on ski-tours) without worrying about damaging the toebar.

The “faith somewhat shaken” in the thread title relates more to how things might have developed in the two failure incidents described if luck hadn’t been on my side.

Carrying a reserve binding has been suggested, but in my particular case that wouldn’t have helped much. Until very recently, I’ve used Araldite Standard (slow-curing, 2-component epoxy) to mount the bindings. Doing so is a bit of a two-edged sword – on one hand I have never (ever) had a binding rip out of the ski, but on the other hand it more or less rules out a field repair/replacement. To get the damaged binding and its partner off the skis I had to place a soldering iron with a chisel tip in the slot of the screw head and hold it there for 60 seconds at 380°C before the seal broke.

Mention was also made of snow packed in the toebar area. This has been given by Alfa as a reason for the toebar pulling out of their boots. Before stepping into the bindings I have always been fastidious about clearing snow from the toebar recess and the longitudinal grooves in the sole. I use the narrow Swix scraper for this, as the “T” end of the scraper fits perfectly into the recess. Packed snow in the recess and grooves of the boot is likely to put more stress on the toebar and the binding.

I have a pair of NNN BC bindings in reserve, but I’m holding back with slapping them on the skis concerned, as I believe there could be an interesting new development in the NNN BC format next season.
Last edited by Jurassien on Wed May 31, 2023 9:41 am, edited 2 times in total.



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Re: NNN BC - faith somewhat shaken

Post by CwmRaider » Wed May 31, 2023 9:02 am

This guy here prefers flexi bindings for polar expeditions:
https://explorersweb.com/secrets-polar- ... -bindings/
https://icetrek.com/shop/flexi-ski-bindings
I doubt that it would be useful for actual steering your skis though



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Re: NNN BC - faith somewhat shaken

Post by mca80 » Thu Jun 01, 2023 5:24 pm

spopepro wrote:
Tue May 30, 2023 6:07 pm
The most recent failure reminds me of a post on a cycling forum from many years ago. Someone was complaining about their Chris King headset biting the dust... after like 100,000km. Sure, you expect tried and true designs to last for a very long time... but none of this stuff is forever. I think you might have just found the EOL of NNNBC. 99.9% of users won't ever sniff it--but you should make inspection/replacement part of your routine.
I've got around 30 or 40,000km on mine, haven't bothered to inspect it. Same with the Phil rear hub, though my understanding is that hub is zero-maintenance and advertised as a hub to bequeath to your grandchildren.



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