Advice needed on NTN mounting for rockered skis

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ski-n-free

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Advice needed on NTN mounting for rockered skis

Postby ski-n-free » Thu Dec 19, 2013 11:59 am

I just picked up some Surface New Life's. These are a rockered, twin tip ski - I'm planning on mounting NTN's on them. I've mounted NTN's a few times before and still have the direction sheets. I'm wondering if there are any issues specific to rockered boards. Anyone have any words of advice?

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Johnny

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Re: Advice needed on NTN mounting for rockered skis

Postby Johnny » Fri Dec 20, 2013 10:12 am

I mounted a pair of NTN on my old rockered Darksides... Just mounted as usual and it was perfect...!

But I always mount my NTN bindings -1 to -3 on my skis. (I mean, 1-3cm in the back of the normal mounting point)... It seems to "Telemarkize" those stupid NTN bindings, makes them more tele, less alpine... : )
/...\ Peace, Love, Telemark and Tofu /...\
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Re: Advice needed on NTN mounting for rockered skis

Postby Johnny » Fri Dec 20, 2013 10:42 am

I wonder if it's too early for the anti-NTN thread and the pro-NTN thread... : )
/...\ Peace, Love, Telemark and Tofu /...\
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Re: Advice needed on NTN mounting for rockered skis

Postby Jeff » Sun Dec 22, 2013 1:02 am

It's never too late to bash NTN. Keep the spirit alive.

I say mount boot center. :)

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Re: Advice needed on NTN mounting for rockered skis

Postby Johnny » Wed Dec 25, 2013 12:18 pm

It's funny, whenever people look at me and ask what I think about NTN, I always have only very bad things to say about it. I wonder why I still ski on them... But I guess the NTN debate is a never-ending one. Even within my own self.
/...\ Peace, Love, Telemark and Tofu /...\
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Re: Advice needed on NTN mounting for rockered skis

Postby ski-n-free » Thu Dec 26, 2013 5:51 pm

Absolutely nothing better to patrol on - step in and brakes cannot be beat! I do miss super comfy boot tho :roll:

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Re: Advice needed on NTN mounting for rockered skis

Postby bogon » Fri Dec 27, 2013 6:24 am

To have a "scientific" answer, please provide at least following:
- ski length in cm, measured (do not trust manufacturer!);
- manufacturer's boot-center mark (measured straight from tail) in cm;
- running surface length in cm, a.k.a distances between contact points in cm (clamp your skis together, slide two pieces of paper (if cambered) above and below tip and tail contact point, measure from the mid-way of two pairs of paper to tail). I do this also for decambered skis. For skis w/o camber only two pieces of paper are needed, obviously; for such skis it is called "rocker lengths";
- ski effective edge in cm (put parallel (!) skis side-by-side and perpendicular to wall, repeat with paper, only at sides);
- location of BoF (ball of foot) relative to boot toe (can be calculated from BSL, toe-to-BoF offset and foot length);
- how much lean do You like in Your boots (relatively - lot, or not);
- if the ski tail is especially soft, or same/harder than ski tip;
- what will You ski - pow, groomers, all-mountain, bc/tours, park? Pick any 3. If park/bc - please also provide center of mass (measured from tail in cm);
- mounting pattern - old 6-hole (Dynafit-compatible), or newer (pink plate/Freedom)? If latter - plese provide distances between holes in mm and from boot toe to foremost hole, cause I only have the older NTN plates at hand.

Given beforementioned data, I'll run my calculations (can provide editable blueprint FreeHand 10 file) - IMNSHO I have all the mounting stuff dialed.

p.s. and no stoopid inches please.
I like all kinds of snow. The only poor snow I know of is ice. That better be climbed.

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Re: Advice needed on NTN mounting for rockered skis

Postby GEO » Mon Jan 06, 2014 7:49 pm

yeah, I do as Bogon above does.... It's pretty fun to understand all the concepts, and do the work yourself.
Perfect and OCD every time. No nasty, hasty errors that I've seen come from some shops. But YMMV. There are folks here who would never dream of mounting their own (I think we've had all those discussion endlessly before!)... Instead, they give them to someone they trust and under?pay 'em 30$ My mounts take longer than 1/2 hour, mainly because of all the ski-specific measuring, thinking and time shooting the shit with other people before drilling holes.

Even experienced shop hands are always learning new things and having to hide screw ups. The best shop hands are those that can drink a lot of beer with their buddies during the pre-christmas shop night, and still manage with get all the mounts and remounts done right. Ultimately however, it is my experience that the mount job & position is not as crucial as we imagine... but the RAT gnaws.....

I went through quite a hunt trying to figure out where to mount S7s from 5cm forward to 2cm back. I think I found replies and info at TGR. How long has TT been down anyway?

SO Bogon - what exactly is "Manufacturer's boot center"and why do they choose it where they do? Sometimes it's a line on the graphic, sometimes a raised of negative mark, or a mark in the sidewall. Or its a specific measurement from the tail (even if the tail has different curves and is a foot off the ground).

I tend to balance actual boot center on the recommended ski "boot center" mark, but keep in mind where BoF (Ball of Foot) falls with regards to CRS (Center Running Surface) - after all if you are carving/skidding both skis, the trailing ski is doing it differently than the leading ski.

I have my double rockered, but cambered FRNTs mounted fairly forward. Really love those skis, and am "Zu frieden" (happy with) NTN. I really like the way they are less fiddly and both alpine and tele well.

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Re: Advice needed on NTN mounting for rockered skis

Postby bogon » Tue Jan 07, 2014 11:28 am

My mounts take longer than 1/2 hour
hehe yep indeedy :-) Mine are half-a-day job: swiss-cheese'ing, tapping and gluing in the inserts - I'm not fast enough to glue more than 4 inserts with one vibro/watertight epoxy portion, it starts to harden too fast; yes I need orange Double Bubble - will solve that. Too bad they cannot package it in tubes - word is its viscosity is uber.

But half-a-day doesn't include pondering time - the latter can take up to week, or even more - depends on ski geometry. There are some strange geometries around... You can look from really different angles on such a ski, but in the end you need to decide between them - that can be hard (if it's your ski, that is; I let the people decide if it's not mine - just providing arguments and decision deadline; much easier ;-).

Our 'quiver' (Tattoo 175 & Mosquito 180 by Movement, TST 192 by Armada - skied them all, but she's yet to ski TST, so cross-reviews are pending):
Image
and its rocker profile:
Image
As You can see, the rocker profile and ski shapes are so different - wide shovel early rise freeride ski, turny double-rockered twintip, and 3-point "fun shape" rockered tank:
Image
Oh, I suppose that's a Movement ski boot center mark?... If yes - they're almost spot-on (see my drawing below):
Image
Note the "uber-paranoid" 7-hole NTN mount pattern :-)

Below You can see the bogus, erroneous, inappropriate SBCM above, and almost erased printed "fixed" SBCM below.

Earlier batches didn't had this "fixed" markings, and I pity those folks for whom the shops mounted their TSTs @ "recommended". Re-mount was absolutely necessity.

The "real" (calculated by me) SBCM is somewhere below the "Austria" word (~28mm back from theirs).

See? They're wrong again. Even after they "fixed" it at -5 from 1st screw-up.
Image
In reality I can't even think on mounting @ manufacturer's "fixed" SBCM - way too far forward.
Even at +14mm (forward NTN detent) from my calculated position (which is -28mm from theirs, so the boot is -14mm in total) they feel too far forward, slight tail wash-out begins. But forward detent is good for parallel, and - all in all - TST is a great ski.

So, the moral is:
Do not trust manufacturer recommendations.
Do not trust shops either - that's your ski, not theirs, so they do not really care.

And this is how I calculate the real deal.

Marks for Tattoo are on the left (in black), and forward detent is close to what Movement recommends.
(mid-boot marks are pink and green for diff. BSLs - see "layers" inspector notes on the left)

Marks for Mosquito are on the right, and middle detent is spot-on for parallel.
For tele I find the back detent (-14mm) works better - less tail washout.
But c'mon, that's parky all-mtn TT after all, so no big surprise here with what manufacturer recommended.
Image
And then the theory goes like that:
Long time ago, in a galaxy not far away, I saved a .maff from old TTalk, and it says:
axebiker: The 3 sets of Movements I've mounted were boot center at 45% of the overall tip-to-tail length from the tail. Had good luck with that
See? That's a really simple rule, but somehow it appears to work sometimes :-)

Next, Marslal Olson from DPS (the maker of 5-point "fun shape" [dubbed "paddle tech"] skis) comes:
marshalolson: i go off all my mounts based on finding the center of the wide point of the tip from the wide point of the tail, aka effective edge length.

the midline of my foot is -6.5cm. I prefer a mount of -7.5 from center of effective edge, as i ski with alot of forward lean in my boots and generally ski with my knees forward of the ball-of-foot and drive the shovel.

i am 99% sure, though i have not actually measured it specifically (ie i personally do not own a pair yet, only been spending time on demo skis on the line), that the RPC is -7.5 from the wide-points. This is something that Stephan, Peter and I all very much agree on... and how the Wailer 99 and Wailer 112 RP listed as midline as well.

a neutral skier will prefer +1 form the midline, or BOF on the center of the sidecut. a more jibby/"modern" skier would prefer +2 to +2.5, as they tend to leverage the tails, and like to be ahead of the sidecut.
Yeah, he's heel-locker, but he too pays attention to ball-of-foot position and boot cuff lean angle.
Those vars are really important.

Sir James from evil Empire (using spooky "imperial" measures) sez:
James: My Scoops are 70.25 inches long chord length. Or tip to tail measured in a straight line on top of the ski.

The boot center mark is 31.5 inches from the tail measured in a straight line. So really close to what Axe biker mentioned.

Mine are mounted boot center on the line and ski best all mountain there but are best in powder at the rear NTN indent or minus 1.5 cm.

I can't imagine having my Scoops mounted any further forward for any reason. On the line they are very pivoty and can ski switch really well.

As for me, I take to account every variable that I'm aware of, including manufacturer recommendations and maggot input, and decide from there:
bogon: Incidentally this point (80cm from tails) is exactly in the center of white cross over green apple on Movement logo :-) And it'll put me 28mm back from BoF-at-CRS mark, and 14mm back from Marshal Olson's recommended position.

So I guess I'll mount NTNs so:
- in middle adjustment detent I'll be in DPS recommended position
- in front detent - BoF at CRS, and
- in back detent - as per Your Scoops Smile
Then I'll ski them some, and ponder which insert pair to share with Dynafit toes.

Next task is to settle on Armada TST 192 mounting position :-D Recommended one is 87.5cm from tail, but I measure whooping 83.3cm from tail to the middle of sidecut (as per Marshal's rec's), and similarily whooping, but differently so, 91.3cm from tail to the middle of sidewall (this is AR50 construction, cap at ends but kinda sidewall under the boot, ~39cm rockered tip). 8cm of difference! Indeed their shape is fun.

So I may drill for BoF at the middle of sidewall (when NTNs are in front detent), and that'll put me 14mm back from recommended at forward detent, boot center at the middle of sidecut at middle detent, and boot center over CRS at rearmost detent. This way Dynafits will end up being mounted near Armada recommended position.

So I've done as I said, and that's about it.

BTW, NTN base plates are doing this to ski topsheets:
Image
Oh, and a bonus for those who care :-)
Image
I ski and climb with this Cordura pack - side straps reduce it to just a 28x55cm slab of 1cm thickness. And that's for 60+L pack that weight around 850g w/o lid and frame (~1100g or 2 lbs 7 oz w/frame)!
Last edited by bogon on Tue Jan 07, 2014 9:05 pm, edited 2 times in total.
I like all kinds of snow. The only poor snow I know of is ice. That better be climbed.

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Re: Advice needed on NTN mounting for rockered skis

Postby bogon » Tue Jan 07, 2014 8:30 pm

forum software was cropping the image, thanx for fixing
BUT
the fix resulted in HUGE page load times - HTML loads, then it sits for ~30 secs doing nothing (I can scroll but cannot click), then suddenly all the pics appear.
This happens on every forum page with pictures that need resizing.

Latest Firefox
here.
All works in SRWare Iron (which is Chrome sans spyware & tracking).

Is JavaScript involved in fix? If yes - then fix the fix, please :-D

p.s. While it sits around, I can see the picture placeholders appear one by one, with ~5 sec gap between them. When the last one appears, then suddenly BANG and page looks normal.
I like all kinds of snow. The only poor snow I know of is ice. That better be climbed.


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