The NNN/BC Truth Thread

[bgregoire]

Midsoles (or innersoles if you want) are most definitely different from boot to boot, especially in the 75mm boots. In the nowegian welts, stiffness mainly comes from a nylon sheet glued between two rubbers sheets, one of which is the vibram outer sole. In theromolded variations (including NNN/BC), the stiffener is usually shaped to the last and glued inside the boot. For example, my Fischer BCX6 NNN/BC and Karhu XCD Descent 75mm both have an apparent nylon like last glued (and or nailed) inside, each of different thickness and perhaps composition. On the other hand, My Alfa Quest Advance 75mm appear to have no stiffening inner sole at all, rather that innersole seems to be made of some type of closed cell foam, perhaps minicell. Alfa tells me this is to create a warmer boot, at the cost of quite a bit of lateral flop.

What you are saying about the biggest sizes being floppier due to lack of extra reinforcement also seems to hold true for (and opposite) the smallest sizes. My Gfrind has the Cripsi Mountain 75mm in a size 38. Its so damn stiff!

Now, i'd also appreciate you take of those modded AT setups you use. Those are free pivots systems, so it would be similar to skiing the NNN/BC with the rubber stopper? Sounds akward, can you really go hard K&Ging, what abour Skating?

[anrothar]

...

Now, i'd also appreciate you take of those modded AT setups you use. Those are free pivots systems, so it would be similar to skiing the NNN/BC with the rubber stopper? Sounds akward, can you really go hard K&Ging, what abour Skating?

Depends on how much you modify the boot.

If you cut out the area at the ball of the foot, as shown in the photos I posted, they K&G similarly to stiffer nnnbc setups, but different. With just the AT toe piece, there is enough free pivot to put your knee on the front of the ski. The bumper in an nnn/bc setup does a few things. It helps to level the ski out when you pick it up, but it also provides a little spring to help propel the ski forward. You would only notice the second benefit when using correct K&G technique on firmer trails though.

If you leave the shell of the boot uncut, or use NTN/Tech boots, you will lose some of the grip you get when you're able to keep the front of the boot planted on the ski through the push off. You also need to use a different gait if the bottom of the boot doesn't, or barely flexes. Glide is the same.

The AT toe piece setups skate remarkably well. They lose a lot to a skate ski setup in weight, but make up much of that difference in control, since the boots are so torsionally stiff. The more tired you get toward the end of the day, the better they perform in comparison to a true skate ski setup, because of the increased stiffness. I can skate Eons and SBound 98's with the AT setup, even on hardpack.

[bgregoire]

I fully understand how the modded AT boot is an improvement over the original At boot for K&G. I do not however understand how the dynafit type binding can be AS good as either a NNN/BC or 3Pin for K&G and skating. I attribute that mostly to unrestricted forward movement. But hey, you say it works fantastic for you, I'm impressed for sure! And that's what counts. I'd love to see more pics of your treks and more talk of this Alaskan race. Cheers

[anrothar]

I fully understand how the modded AT boot is an improvement over the original At boot for K&G. I do not however understand how the dynafit type binding can be AS good as either a NNN/BC or 3Pin for K&G and skating. I attribute that mostly to unrestricted forward movement. But hey, you say it works fantastic for you, I'm impressed for sure! And that's what counts. I'd love to see more pics of your treks and more talk of this Alaskan race. Cheers

Just in case there's any confusion, I have not done the Wilderness Ski Classic. I'm planning on it next year.

I could also be completely wrong about all of this and just making things more difficult on myself?

I think, for k&g, the bumper makes a big difference in set tracks, and not much difference everywhere else. In set tracks, it keeps the tip of the ski you just pushed off from in the track, so that it can return directly to the track. It also provides a small amount of propulsion on the ski being kicked forward, but again, I doubt that adds anything noticeable outside of a smooth, groomed set track.

For skate skiing, I'm guessing that in addition to the tiny bit of propulsion the bumpers provide, they just serve to keep the super lightweight race skis somewhat level, so that you can land on a level ski and not catch the tip or tail while bringing the ski back to center. Heavier(even 1800gm/pr) backcountry skis have no problem staying level when picked up if mounted anywhere near the balance point. My SBound 98s are mounted at balance point and stay perfectly level, no matter how quickly I pick them up. My Pellestovas are mounted about a cm behind balance point and also stay level when I pick them up, but if I hold one of them up, with toes pointed down, the tail will very slowly rise to meet my heel. Kind of like the super long poles tightrope walkers use to help keep their balance.The weight makes them slow to tip when held near the middle.

EDIT: The stiffer skate ski bumpers probably also help encourage people to push off of a flat foot, instead of the toes. If you know how to push off of a flat foot, that feature is a lot less necessary.

Downhill control and herringbone, a non-free pivot is superior. Herringbone in anything more than a couple of inches of snow with just toe pieces is way slower and more difficult than with nnnbc. I would assume 3 pin has the same advantage.

EDIT: The only reason I can think of that the AT toe piece set up beats nnnbc for downhill control is the plastic double boot. A plastic nnnbc boot would probably make nnnbc incredible on the downhill, but might be too strong for the plastic binding to last? Maybe plastic nnnbc boots would have to match up to some bindings with aluminum in place of a large amount of the plastic.

[MikeK]

I may be wrong on this but I had thought the flexor was to keep enough pressure on the ski through the stride to optimize the force transmitted downward to the ski with the forward propulsion i.e. to give you optimal use of your wax/scale pattern, which extends forward of your toe. And so you can use the whole extension of your foot right to the tip of your toe but you can do the same with any free pivot binding. 3 pins restrict that last little bit of extension. Too much resistance and you'll just be driving the ski into the ground or driving the tips into the snow in deep stuff, wasting energy.

Never used stiff flexor, stiff cuffed skate gear. No idea. But binding freedom seems less important for skating IMO i.e. I want the ski to stay closer to my boot. I used to skate with pins a lot when I was younger. When I tried with BC 3 pin boots I hated it. Not sure why. Weight, stiffness, etc. I can skate great with my NNN BC boots. Same ankle support, similar weight, just something about how the BOF contact feels makes them feel way more natural. FWIW I can skate, as can most, with rigid Alpine boots. It sucks and I wouldn't do it more than few hundred yards. So when I mean skate great, I mean feeling like I am on ice skates.

In unbroken snow, you are correct, depending on the type I guess and how well your skis float and plane up. I've thought about removing my flexor a couple times in really heavy, dense snow where I was sinking a lot. I don't see it's resistance providing much benefit there, it was probably actually detrimental in not letting the tips plane up as much.

A lot of snows though, not the case. Still can stride like normal and use the full extension/downward resistance of the flexor.

[anrothar]

As far as I know, in correct k&g technique you engage the wax with a flat foot, and and it stays engaged while your toes are still flat on the ski, once your toes pivot up(and the front of the boot contacts the bumper), your wax pocket is disengaged and that ski moves into the swing-glide phase. The wax engagement is supposed to happen pushing down, not back. By the time your toes contact the bumper, your foot is behind you, so you would be pushing back, which will result in slipping. Maybe it could be exploited with scales to add a little extra grip, but it's not orthodox technique.

[MikeK]

I thought perhaps it was all about the controlled release of energy right at the end of the kick phase as the ski transitions from being on the snow to off. This is where I feel the difference in skiing NNN and 3 pins. I can't get that last little snap like I can with NNN with pins. You can still get that with a freer pivot, but I'm not sure it would be as well controlled. The ski might flop and you may not get the optimal force transfer - K+G is all about one thing in my mind, transmitting as much traction to forward motion and glide.

I think what you are talking about as correct technique is correct. The BOF stays flat through the lunge, but it's the release and transition to release I was talking about. I'm pretty sure you are still getting energy transfer there... like a lot of if the ski has camber and stored energy. Like I say, it's really the only difference I can feel between pins (without cables) and NNN for a diagonal stride.

[bgregoire]

Luc has a lot of sound info relevant to this discussion here:

https://thingstolucat.com/ski-touring-equipment-guide/

I agree with most everything he has to say, especially about the 75mm / NNN/BC bit

Relevant info about those AT boot and bindings too...

[MikeK]

Luc has a lot of sound info relevant to this discussion here:

https://thingstolucat.com/ski-touring-equipment-guide/

BCNNN/BCSNS

The advent of BCNNN/BCSNS boots has done a serious disservice to long ski touring market. The boots became so popular with the low-use (weekend) market that they edged out the more reliable 3-pin options. The BCNNN/BCSNS boots aren’t built to withstand a long or rugged trip. Don’t be fooled by the marketing, they fail all the time and your boot will end up strapped to the ski at some point. Dave Cramer, the Alaska Mountain Wilderness Classic organizer, says: The fact that the skiing public puts up with it [BCNNN/BCSNS boots] is either a testament to the power of mass marketing or a measure of how few people really get out and do the multi-day mixed terrain trips anymore– probably both.

Bindings

BCNNN/BCSNS bindings are pretty reliable, the problem is with the boots. The most common complaint with BCNNN/BCSNS bindings is about icing up. In addition to being annoying (Eben Sargent’s boots were frozen onto his skis for 2 days in the Brooks Range), icing can lead to bending or breaking pieces within the binding. BCSNS has a slightly better reputation for ease of de-icing.

Boots

All boots are reviewed as being somewhere between ‘OK’ and ‘they suck,’ so there aren’t any specific recommendations. The great hope are Alfa boots, but I don’t know anyone who has used them. The Alfa Polars are the go-to for Greenland traverses and look really promising for cold weather trips.

The most common boot failure is the toe-bar loosening or completely pulling out of the boot. The boot material and seams also fail with low mileage, especially on the top and sides of the toe box where the boot flexes. Zippers break and ice up too. The waterproof models are not waterproof, though you probably don’t want a waterproof boot on a long trip, you can be certain to soak it from the inside, if not out.

Despite these problems, BCNNN/BCSNS boots are light, comfortable, and skate-ski well. If you aren’t too far removed from the road system, they might be worth considering.

http://thingstolucat.com/ski-touring-equipment-guide/

Which was part of my response here in regards to this a couple weeks ago:

I weigh around 210 at 6'3" and am on the 205 Eon. I've been using them with NNNBC Magnums, modified to prevent freezing up, the entire time, but am about to switch them over to AT toe pieces and chopped at boots, which is what I have on the Pellestovas, Sierras and SBounds. At size 49, I've found the sturdeist Rossignol and Alpina boots to be too easily twisted in the forefoot in comparison. The AT toepiece setup, with properly cut down boots, weighs less, turns infinitely better, skates better and k & g's about as well.

Mind going into some detail (picture perhaps) outlining this. Never heard of this before and it sound intriguing.

Singletrack:

They do well as long as it isn't too twisty and doesn't have too many steep climbs where the length is prohibitive. The Sierras are much, much better for singletrack. In fact, I would say they're almost the ideal singletrack ski.

Interested in where the Sierra falls in between this and the S98. I find the S98 to be a very good ST ski, mainly due to it's turn and immense grip. The Eon is OK, it just can't get up steep hills as well.

Hopefully my parsing of the quoted text worked....

Luc Mehl has been using the AT toepiece setup far longer than I and explains the pros/cons pretty well.

http://thingstolucat.com/ski-touring-equipment-guide/

The only thing I do different is to take a hole saw to either side of the boots where the bellows on a plastic tele boot would be. I also leave the cuff attached, but trim it down as much as possible. After gluing in a gaiter, this allows them to flex in the forefoot like a stiff nnnbc boot, but with most of the torsional stability of an in tact plastic boot. Combined with the completely free pivot, they tour on mellow terrain exceptionally and skate ski as well as any high end skate ski boot. I can even skate the SBound 98's comfortably with this setup if the snow is warm enough or firm enough. I mount the bindings with pivot a hair behind the balance point so that the skis slowly level themselves out when picked up. I'll attach a photo of what my old Scarpa Magics look like modded this way. Currently on Dynafit Mercury.

12646639_10207232338024060_7819041873832716513_o.jpg

Regarding singletrack, I find the S98 to be a little too wide if it's been a while since the last snow on a high bike traffic trail. The Sierra behaves nicely in a slightly bowled out tread that often occurs in those situations.

Which was posted in this thread:

http://www.telemarktalk.com/viewtopic.p ... =40#p13458

But I didn't want to detract from the Eon reviews.

So have we come full circle?

[MikeK]

At this point in the discussion, I'm actually more curious about the flexors actual function in K+G, which also puts us back on topic. I did a quick search and found absolutely no relevant info regarding it.

One cool thing I did find on the Rotte site:

All Xcelerator bindings are delivered with a medium flex (black). Switching to a softer flex (light grey) will make it easier to bring the ski forward after the kick. In particular, people with low weight and smaller feet will benefit from changing to a softer flex. A hard flex (dark grey) will make the ski more responsive, and can be used in terrain where there is a lot of doublepoling.

This was their pitch for Classic tuning. Not sure what they mean by more responsive.

PS This isn't the first time the debate over resistance vs free pivot for touring has come up here. Seems to me, for going slow, uphill climbing or in deep snow breaking trail, the free pivot is advantageous. For striding on rolling terrain in snow that isn't heavy or bottomless, I think I'd prefer the resistance of the flexor.