Mounting 3-Pin over Xplore

[JohnSKepler]

I've got this project going to mount a 3-pin binding alongside my existing Xplore. Hoping the community can help me answer a question.

I'll be using the Rottefella Supertelemark binding with the Voile Transit 10mm riser on a 172 cm Falketind 62. The following pic shows the location of the various mounting holes and locations.

The holes in the ski, filled with inserts, are the existing Xplore mounting points. Above it is the Voile riser with it's holes. The four large holes in the riser attach to the ski. The smaller holes in the riser attach the binding to the insert. Interestingly, the four holes in the square pattern on the right of the ski, two large and two small, align perfectly with the four holes of the Xplore mounting. I keep trying to think of a way to use that but it puts the pin line way too far forward.

Notice the red-hatched areas marked on the ski, which is a Falketind 62. Ryan at Binding Freedom recommends not putting inserts within a centimeter of existing holes, which I'm interpreting as 1 cm edge-to-edge, not 1 cm center to center. So, I can't put any holes in the red-hatched area which limits where the pin-line can go, and, in fact, it cannot go on the balance point (BP), which is marked by the black line through the center of the exclusion zone. The second photo shows where the pin line can go.

The black line in this photo is the BP of the ski which is also the centerline on this ski, at least within 1/16" of an inch. The blue lines show where the pin line would be if I used two existing holes to mount the riser. If I do this, which only requires drilling two additional holes in the ski, the pin line can be either 75mm ahead of the BP or 35mm behind the BP.

However, if I drill four holes, the closest the pin line can be to the balance point is marked by the green lines, either 12mm ahead or 52mm behind the BP. So the closest the pin line can be to the BP, no matter how I drill, is 12mm.

To me, it seems the best choice is the configuration that places the pin line 12mm ahead of the BP. Doing that would mean I have two new holes just to the left of the exclusion zone and two new holes some distance to the right of the exclusion zone. But, I have also had recommendations to put the pin line at least 5mm behind the centerline. I've read up on this but don't have enough direct experience to make an informed decision.

What sayeth the gurus?

[Manney]

12 mm (less than half an inch) is not significant. Wouldn’t lose any sleep over it.

Ideally, this could have been brought down even more by planning both patterns in advance. Split the BP difference between XPlore and 75/riser. That’s a really useful take away that might get lost along the way if not pointed out (not trying to be a dick.. just capturing a lesson for posterity).

A really anal approach after-the-fact would be to change the balance point by putting a length of top sheet protector on the light end. Doesn’t take much to move the balance point 1/4”. A spare insert screw or two (but a low profile torx or hex pan head, not a flat head hitch is beveled at the bottom) would prolly do the same thing provided there’s clearance. This is kinda OCD tho. But if it helps you sleep at night…

[tkarhu]

Good point, I guess a binding cable already changes a balance point noticeably. Doesn’t a balance point move backwards, when you install a cable binding? Ski balance point before installing a binding is actually not very relevant in theory.

[Manney]

It’s more critical to k&g than to glide. It’s about how the ski reacts at the end of a kick or when stepping in/out of tracks.

When the weight is on the skis (however equally) on the down, you’re right in saying that the overall balance of the system (ski, binding, boot, skier) is what’s important. On those terms, mounting a binding fractions of an inch ahead or behind the balance point loses all practical meaning.

Everyone has their prefs. Half or more is in the head. Explains why most skis are brightly colored.

[JohnSKepler]

12 mm (less than half an inch) is not significant. Wouldn’t lose any sleep over it.

Ideally, this could have been brought down even more by planning both patterns in advance. Split the BP difference between XPlore and 75/riser. That’s a really useful take away that might get lost along the way if not pointed out (not trying to be a dick.. just capturing a lesson for posterity).

A really anal approach after-the-fact would be to change the balance point by putting a length of top sheet protector on the light end. Doesn’t take much to move the balance point 1/4”. A spare insert screw or two (but a low profile torx or hex pan head, not a flat head hitch is beveled at the bottom) would prolly do the same thing provided there’s clearance. This is kinda OCD tho. But if it helps you sleep at night…

I thought about this, too. I'm fairly new to the sport - just a few years, but do work hard to learn and contribute, mostly because learning new things is fun and rewarding. However, when I mounted the Xplore last year, going 75mm was not on my radar. In the future, when I mount bindings, I'll definitely think about other bindings I may want to mount in the future.

Good point, I guess a binding cable already changes a balance point noticeably. Doesn’t a balance point move backwards, when you install a cable binding? Ski balance point before installing a binding is actually not very relevant in theory.

This is a great observation. I will check the balance point with the 75mm binding installed and with and without the cable, just to see.

With the cables off is more of a "touring mode" and the balance points will be close to the non-binding balance point. With the cables on is more of a skiing mode and will shift the balance point backwards quite a bit. I'm thinking, because this will be a tour-for-turns configuration, it would make the most sense to forget about the balance point and pin line and mount the binding at the ball of foot on center running surface. That would put the yaw rotational force at the geometric center of the usable edge optimizing down force into bending the ski.

[tkarhu]

True. For comparison, a NNN-BC binding has mainly thin plastic towards tail from pin. All mechanical parts, and most metal parts, are towards tip from balance point. So mounting a NNN-BC binding will probably move balance point forward. I could maybe even measure this because I have uninstalled FTX’s and NNN-BC manual bindings. Same applies to XC bindings I guess.

[Manney]

Yours is an interesting approach @JohnSKepler. Wouldn’t underestimate it by calling it an “experiment”. The outcome is more certain. The real juice is in the approach, which you’re giving us insight into. So thanks for that.

It’s probably one of those things that would send shivers down the spine of ski execs, which makes me love it all the more. So keep going… innovation is ultimately good for skiers who want to do terribly subversive things like enjoy the same ski in a different setup.

[tkarhu]

Agree. @JohnSKepler If you would install quiver killers at both the spots you considered initially, would screw holes interfere with each other? Testing is also what quiver killers are there for I guess. And a personal experience could be more valuable for you than a thousand opinions from others. Experiments are often gold.

[Lhartley]

I like to experiment with regular screws and then quiver killer the final positions that I use regularly, QK are $$$$ and you can always install QK in holes already drilled

[JohnSKepler]

I like to experiment with regular screws and then quiver killer the final positions that I use regularly, QK are $$$$ and you can always install QK in holes already drilled

So…. How many hole can I put in a ski!