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Binding Mounting Position

post #1 of 19
Thread Starter 
Got new boots, so I thought I would revisit where my bindings are mounted. I made a poor man's balancer, and marked my boots where I am balanced fore/aft. Next I measured and marked the center of the running length of my skis.

I understand the concept of the boot balance point, BOF etc. However why do you choose the center of the running length of the ski? It would make sense if the ski had a uniform construction from tip to tail, and thus the flex point would be the center. However, my RX8s are not uniform. They have the Railflex plate and in front and behind the plate there are structural components that create a rise in the ski.

Fischer puts the mounting arrow dead center of the plate and between the front and back bumps. The CRL method moves the point 1.5 inches forward.

Any thoughts?
post #2 of 19
Your post is timely for me -- I just got new boots for my daughter, and stumbled across some of the older discussions about fore-aft binding positions.

Two nights ago I tried using a roller excercise board with a fixed pivot point to make a balance board, but I got some strange results with her, so I just went with the BOF/CRS method. This puts her boots about 1cm ahead of the Atomic factory marking. I moved the front bindings, and she'll be set to go after I recheck the DIN settings.

I also tried the balance board on me, and got more normal results showing that my boot tips should be 3.25cm ahead of CRS. However, the best I can do is to adjust my Atomic bindings all the way forward (2cm), but it is still too far behind. I'll ski on them to try this position, and then decide if I want to redrill and move the bindings.

Your question about flex points is good, but I don't have a full answer. My SX9s also have raised structural components. The idea of centering the BOF to the CRS is based on the idea of centering the skier's weight to the physical area in contact with the snow, and maybe this would still need adjustment depending upon construction (soft tails, etc.).

Take Care,

Scottie
post #3 of 19
Why don't you try it at each of the points you want to try. Start with the center mounting hole, and compare it to the forward mounting hole. If the forward hole is better, then try adjusting your toe piece as though your boot were longer and adjust your heelpiece as if your boot were shorter by the same amount. Make gradual adjustments and take time to feel the difference and to acclimate your skiing to the new positions.
post #4 of 19
Thread Starter 
That is what I am planning on doing. Just wanted to get a theoretical take on the issue.
post #5 of 19
Quote:
Originally Posted by fischermh View Post
I made a poor man's balancer, and marked my boots where I am balanced fore/aft. ....
<snip>
Any thoughts?

Play around with small shims under the heel to see how much that balance point moves with ramp angle.
post #6 of 19
More info:
http://www.lous.ca/techarticles.htm
http://www.techsupportforskiers.com/..._placement.htm

There's a lot to be said for using bindings with adjustable positioning...Tyrolia, Atomic, maybe others. I ski with my Tyrolia and Atomic bindings set as far forward as they'll go on pack, and on the mark on powder.


Ken
post #7 of 19
Thread Starter 
Anyone know the delta for Railflex bindings?
post #8 of 19
This post is good timing for me as well.

I also got some new boots and they are alot smaller than my last ones (307 mm to 292 mm), so.... I moved my rear binding forward to make it fit the boot but.... now my center of boot mark is about 1 cm or more ahead of the mark on the ski.

I would like to try the new boots at the OEM mark and boot centered but... would also like to be able to try them 0.5 cm and 1 cm behind the mark.

I know there are adjustable bindings out there that allow fore and aft adjustment but what are the manufacturer and model of such a binding?
post #9 of 19
Thread Starter 
Tyrolia/Fischer Railflex have three positions -15 mm 0 +15mm. You can also move the toe and heel pieces for more adjustment
post #10 of 19
With my 305mm boots, I can get an even 2cm adjustment to the front (from nominal) on Atomic Device 412s. I am mainly interested in moving towards the front, but I could probably get 1cm or so to the rear, too.

If I want more than that, I'd have to redrill and move the factory-installed rail plate, and I'm not sure if that is supposed to be done on these skis (Atomic SX9s). Anyone know? Atomicman?

Scottie
post #11 of 19
Quote:
Originally Posted by Scottie61 View Post
With my 305mm boots, I can get an even 2cm adjustment to the front (from nominal) on Atomic Device 412s. I am mainly interested in moving towards the front, but I could probably get 1cm or so to the rear, too.

If I want more than that, I'd have to redrill and move the factory-installed rail plate, and I'm not sure if that is supposed to be done on these skis (Atomic SX9s). Anyone know? Atomicman?

Scottie
If they are like the device bindings on my Betacarve 9.18's, they can be adjusted more forward by setting the toe piece forward by some increment, for example if the boot sole length is 325 using the boot sole length setting for 345, and then changing the heel set up in the opposite direction by the same amount, in the example here using the setting for a boot sole length of 305. This is exactly what I suggested for the Railflex bindings as well. The device bindings are harder to do this with because they are more touchy on installation, but the process works if you want it to. The flex point atached to the ski will still be in the same place, but you can't have everything, and it is a lot less difficulat than redrilling your skis.
post #12 of 19
Fog,

If I get your explanation, I think I am already doing that. In doing that I can go forward 2cm. If I wanted any more than that, I would either have to move the whole plate by redrilling or lengthen the slotted portion of the toothed holder. If needed, the latter fix is less drastic. The guy at the shop didn't recommend moving the plate -- he wasn't sure if the ski was structurally able to have different fasening holes. I would need an Atomic guru tell me if that is an issue.

I'm not sure that changing the binding anchor point (w/respect to my foot) is that big of a deal.

Like I said, I'm 2cm forward from Atomic's nominal position, and if I get out this weekend, I'll try it. I have a cold right now...

It still isn't far enough forward to get my BOF lined up with CRS tho, but who knows, it may be good enough for me.

Thanks for the input!

Scottie
post #13 of 19
Thread Starter 
I measure the difference in the height of the toe and heel piece over the length of my boot. It was 2mm. Add 2mm of duct tape to each boots heel. Did the balancer again. It moved the balance point about 2 cm.

The Railflex allows alot of flexibility with respect to mounting the bindings. I remounted the bindings with the balance point lining up with the arrow Fischer put on the skis. It resulted in moving the binding back a considerable amount. I know this kind of runs against conventional wisdom, but it seems to make sense to me that the skis sweet spot will be in the center of the plate as opposed to the CRL.

Easy enough to change if I don't like it.

Mark
post #14 of 19
post #15 of 19
Yup -- that is one of the articles that got me interested in this subject.

Others:
Use of Campbell Balancer
http://www.lous.ca/Articles/nordica%20report%20revA.pdf

From another forum
http://snowheads.com/ski-forum/viewt...=13503&start=0

Scottie
post #16 of 19
FischerMH: Where you mounted your skis is probably too far back. Remember from other posts that the mark the manufacturer puts on the ski has nothing to do with any anatomical part of the ski. It represents nothing other than where they want the center of the boot on that particular ski. The plate was then mounted so the plate center corresponded with the mark.

Your reasoning is reasonable only if your assumptions are correct. But I think you will find they aren't. Find the center of the ski running surface then put the BOF there and you will probably be happy.

Although I haven't measured the RX8 I have skied it and would guess the factory position and the BOF/CRS position aren't that far apart.

Lou
post #17 of 19

More beating of the mounting position dead horse

Just an observation, FWIW:

I just bought some Rossignol Passion II skis with Saphir 90 bindings for my daughter. This should be a good intermediate ski for her.

I have read that the French ski mfrs typically mount farther forward than the German/Austrian ones, etc. and the fact that this is a woman's ski may come into play, too.

When mounted as prescribed, the BOF is about 1 cm forward of the CRS, and the boot center is about 1/2 cm forward of the factory mark. This is way different than I've seen with our Atomics.

The front of thise ski has an interesting curvature, so my CRS position may be suspect. These bindings are on a plate, so they are easly movable, if needed.

Scottie
post #18 of 19
Thread Starter 
Lou,

You are right. I ended up mounting the binding so the balance point of the boot is over the CRS. Skis very well.
Quote:
Originally Posted by race510 View Post
FischerMH: Where you mounted your skis is probably too far back. Remember from other posts that the mark the manufacturer puts on the ski has nothing to do with any anatomical part of the ski. It represents nothing other than where they want the center of the boot on that particular ski. The plate was then mounted so the plate center corresponded with the mark.

Your reasoning is reasonable only if your assumptions are correct. But I think you will find they aren't. Find the center of the ski running surface then put the BOF there and you will probably be happy.

Although I haven't measured the RX8 I have skied it and would guess the factory position and the BOF/CRS position aren't that far apart.

Lou
post #19 of 19
Good!

Glad to help.

Lou
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