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Re: New Approach to Binding Mount position; split from Stockli Laser SX review.
Posted by HighAngles on 31 Dec, 2012 17:39 -
I thought the binding mount position thoughts brought into the ski review worthy of it's own thread.
I usually find my eyes glazing over, but this I understood.
Would love to hear more thoughts from the forum.
Lynn
Nice to hear that you found the sweet spot on the Laser SX. Quite frankly, the Laser SX is about as kick-ass as skis come. It's on my buy list and I'm actively looking for a good deal on a pair (170cm).
I had an interesting chat with HH at short turns camp regarding binding mount position. I was already leaning in this "new" direction, but HH has absolutely confirmed my current thoughts on the correct mount position. I started out using the BoF over center of running length and that evolved to the BoF over center of effective edge, but I started realizing that the point I was finding to work really well for me also corresponded to have the boot midsole aligned with narrowest point on the sidecut of a ski. Without any real "prompting", HH said that this was also his experience and he explained that when you think about what happens when a ski is flexed into an arc, having the boot midsole at the narrowest point is the only mounting position that really makes the most sense. So I have gone back through most of my skis to double-check where my boot midsole sits in relation to the narrowest point of the sidecut and amazingly they almost all are dead on.
I'm going a bit further now, with the hypothesis that when your BoF lands on the center of effective edge AND the midsole mark on the boot also lands exactly on the narrowest point of the sidecut, magic happens. The skis that I own that match this criteria are the ones that I feel are completely dialed in for me. This clearly plays into the ski design arena and I wonder how many ski builders are aware of this relationship when designing the ski geometry. -
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Great review - thanks John. I have read a number of reviews in the European German-language media about the Laser SX, and they all rave about this ski. Your comments re. binding mounting point seem to similar to my experience on the Stormriders that I tried last season. I had to get waaay forward over the shovels to make that ski work, and the bindings were clearly mounted too far back. Interestingly, the shop mounted them at the BoF/CRS mark.
HA - you make a distinction between BoF/CRS and BoF/effective edge. What's the difference? I have never heard of a reference to effective edge. Furthermore, how are you determining the narrowest point in the sidecut? Seems to me that there might be a significant portion (couple of centimeters at least) of the ski that would measure almost the same dimension using an ordinary ruler, at least with my middle-aged eyes squinting at the little marks. Do you use a micrometer?
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Svend - thanks for the interest and here's more detail on the subject since Lynn has so nicely broken this out into its own topic.
For years and years (long before we had factory mounting marks on skis and boots), skiers used the Ball of Foot (BoF) positioned on the Center of Running Surface (CRS, aka midpoint of the running length) when mounting their bindings. Even after we got the factory mount mark on skis and the boot midsole mark, some skiers still preferred to go with BoF on CRS. Of course this was before ski sidecut geometries and tip/tail profiles got, let's say, "interesting". With dual sidecuts, early rise tips, and full-on rockered 5-point designs, BoF on CRS no longer produced the desired results (since determining CRS becomes quite problematic). There has also been some confusion/controversy over how to properly determine where the BoF point really is on your foot and where that point is positioned inside the boot shell. For the purpose of this post it's not necessary for me to get into the details of those issues.
So BoF over CRS evolved into BoF over CEE (Center of Effective Edge). The Effective Edge length is the distance from the widest point of the tip to the widest point of the tail. What makes CEE slightly tougher to determine is that it's the length "along" the edge, not the chord length between the two widest points. IOW, you need to use a flexible tape measure to really do this right; to determine the midpoint between the widest points of the tip and tail.
Unfortunately even BoF over CEE fails with some of the more modern takes on ski design. Some builders do some strange things with the positioning of the ski sidecut and also their new takes on ski rocker profiles. That's where simplifying the whole process by just aligning the boot midsole mark over the narrowest point of the sidecut makes a lot of sense. For this to really work well though, I would recommend that you have a fairly close fitting boot so that the midsole mark on the boot actually corresponds to the midsole point of your foot.
The best method I've found so far to determine the narrowest "point" on a ski's sidecut is to use a digital caliper. Use the caliper to find the approximate narrowest point along the sidecut and then lock the caliper's measurement adjustment (usually there's a thumb screw to lock the jaws in place). The narrowest waist measurement will sometimes occur over a "range" in the middle of the ski; possibly for 2cm or more. This can be handled by taking the locked calipers and marking the forward and rearward points where the locked calipers "catch" on the ski (slide the calipers through the narrow range and mark the forward and rearward points). With those points marked, measure and find the midway point between them and mark that point as the narrowest point of the sidecut (basically it's the middle of the narrowest range of the waist found). The main problem with this method is keeping the calipers square to the center line of the ski while taking the measurements. I'm still working on a type of jig that can make this process faster and more accurate. -
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Hmmmm....very interesting subject. For years I used to do the BoF/CRS thing on all of my family's skis, and then found that on some skis this just didn't create a sense of a balanced stance. Either the tails were washing out, or one would have to get way forward to get the tips under control and to engage. So I have almost abandoned this method due to too many instances where it simply didn't work -- my wife's im78's, her Progressor 8's, my Progressor 9's.... The final straw came when skiing the Stormriders last spring -- as mentioned, the shop set them up for my friend at the BoF/CRS mark (Knee binding, flat mounted), and it was simply a terrible spot to mount them - felt like it was about 2 cm back of where it should have been.** The shop owner, who is one of the boot fitters on Epic, has long been a vocal proponent of this method, and was punting it to my friend as the magic spot on the ski and the only way to find a mount location. So much for that theory.
They were almost unskiable.
This is no big deal for skis with adjustable bindings or plates, as I have simply moved the binding until the skier feels centered and balanced, and the tips or tails are well weighted and under control. But for skis that are flat mounted this is a real dilemma. I have been at a loss to find another method to find a balanced stance, as I am understandably reluctant to go back to the shop for repeated re-drilling. Both of our daughters have twin tips that are flat mounted, as are my wife's Dynastar all mtn. skis, and I guess I have been lucky that the BoF/CRS seems to have worked well for them - the skis handle well, with no apparent issues - but they are all traditional camber and sidecut geometry. However, our youngest is nearing the point when she will have outgrown her Fischer twins and will be ready for a longer ski. Those that I have been checking out for her all have at least early rise, if not some tail rocker too, and I didn't know where to start trying to find a good mounting mark on those, so I had been planning on getting a plate or rail type binding.
Skier stance likely plays a role in this too, I would imagine. My wife, for example, has as her natural stance a rather forward, low and aggressive position, brought about by years of power skating since childhood. Our daughters, OTOH, are much more upright, albeit still driving the shovels with shin to boot tongue pressure. But their fore-aft weight balance is clearly going to be different over the skis. In your experience, does this have any influence on where your final mounting mark settles? Have you set up skis in this way for others, or just your own? In other words, have you mounted according to measurements, only to find that it didn't work for a particular person because of stance peculiarities?
Overall, though, your description of CEE and narrowest sidecut point are extremely interesting. Encouraging, too, that I now have a real alternative to finding the correct mounting point on a rockered and/or multi-sidecut ski, leaving the option of a flat mounted binding still open. You've piqued my curiosity, and I am going to do some measurements of our own skis to see how they line up. My P-9's would be a good candidate, and my wife's iM78's. I don't have a digital caliper, but I do have a micrometer that might serve for now. Re. midsole mark on the boots, I'm not sure if your criteria for a tight fore-aft shell fit is the same as ours, but all our boots are 1/2" to 3/4" gap at heel, toes touching, on a footbed. Hopefully that matches well to the mid-foot spot.
Thanks, H-A. Great post.
**Correction: I just re-read my own review of the Stockli's, and found a note that, while the bindings were indeed set up at the BoF/CRS mark, there was also a riser plate of 8 to 10 millimeters thickness placed under the toe piece, but not under the heel. This would doubtless have influenced my impression of the bindings being mounted too far back.
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H-A:
Postulate a little bit along the lines of Svend's line of thought. The mount point for women skiers is generally accepted as being farther forward, and the distance between the BoF and the center of the boot is also generally less because of shorter boots.
Would you adjust your approach for women (or for taller than average guys with longer feet)? -
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Jim - I have long trumpeted the fact that skiers with different BSLs would end up in different positions of their BoF over the ski if they all mounted at the factory mark. This was especially an issue for women (and guys with small feet) since their BoF would be much farther rearward.
But here's where things get interesting (and I need more data) - many ski manufacturers do NOT put their factory mark at the narrowest point of the ski sidecut. When they don't it's almost always rearward by a large margin. I believe that HH's point was that it isn't about the positioning of the BoF any longer (not in modern skiing style), but more about being centered over the narrowest point of the sidecut. I didn't get into exactly why this is important previously, but I'll lay it out now. Pretend you have a machine that can bend a ski into a complete arc while stationary on the snow. While the ski is bent deeply, place your ski boot on it at your chosen mount position. If this position is forward of the center of the bent arc then the mere act of bending a ski will put you in the back seat. Can you see why? Because the toe will be more "up" and the heel will be more "down" into the center of that arc. By the same token, a rearward point will have the toe down and the heel up which obviously wouldn't necessarily put you in the back seat, but it certainly wouldn't be in balance against the arc of the bent ski. So the idea is that a bent ski will have the deepest point of the arc (the apex) at the narrowest point of its sidecut when skied on hard snow. Now clearly, many skiers never really bend their skis much at all so the degree of the effect of this situation will vary with the skill level of the skier. The corollary to this is make sure that you can actually bend your skis at the speeds you typically ski. If the ski isn't really getting bent in a turn then you're really not taking advantage of the design of a ski to make it turn.
Another point, consider the design of women's skis. Manufacturers should be doing a lot more than just making them softer/lighter and changing where they print the mounting line on it. They should be adjusting the sidecut position relative to the Center of Effective Edge. That means that they should not just be putting pretty colors and chick-inspired graphics on the same ski that's in the men's line. They should really be developing the skis differently from the ground up to work better for lighter skiers with smaller feet so that the sidecut and the ski profile mesh well for a smaller skier. -
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HA, really great info and thoughts on the subject.
Interesting theory on women's skis too.
I wonder if the combo of the mounting point and demo bindings results in the foot pain
I experience when I demo most skis.
Bottom of my foot begins to scream after a run or two.
I demo'ed some ?blossoms? with vist bindings 2 years ago at the North East PMTS meet up and
was in near agony. Had to get them off.
Not an isolated experience.
Your thoughts on women ski production sounds like an idea whose time has come.
Some savvy entrepreneur should take up that as their marketing strategy!
Women skis made for real women skiers; not just another pretty ski.
Jim has some bindings to check out this weekend
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Skier stance likely plays a role in this too, I would imagine. My wife, for example, has as her natural stance a rather forward, low and aggressive position, brought about by years of power skating since childhood. Our daughters, OTOH, are much more upright, albeit still driving the shovels with shin to boot tongue pressure. But their fore-aft weight balance is clearly going to be different over the skis. In your experience, does this have any influence on where your final mounting mark settles? Have you set up skis in this way for others, or just your own? In other words, have you mounted according to measurements, only to find that it didn't work for a particular person because of stance peculiarities?
**Correction: I just re-read my own review of the Stockli's, and found a note that, while the bindings were indeed set up at the BoF/CRS mark, there was also a riser plate of 8 to 10 millimeters thickness placed under the toe piece, but not under the heel. This would doubtless have influenced my impression of the bindings being mounted too far back.
Svend - As noted in your correction, binding delta and boot ramp angles clearly impact fore/aft balance. It's a system; boots, bindings, and skis work together and if any one of those elements are not matched well to the skier then the performance will suffer.
I try not to include fore/aft balancing considerations when determining or experimenting with mounting locations. My assumption is that the fore/aft alignment has already been sufficiently handled between the correct meshing of the boot forward lean, boot ramp, and binding delta. Determination of whether or not you actually have this dialed in though must be determined through video or by an instructor skilled in assessing fore/aft alignment. Skier "feel" is not sufficient to figure out if you have this element appropriately setup.
Ski flex patterns can also have an influence over whether a skier feels balanced (dialed-in) on a ski with a specific binding mount location. Some skiers prefer softer tip/stiffer tail setups, some more balanced equally, while a few even like a stiffer tip with a softer tail. Once again, I do not include those variables in the data I've been tracking for binding mount location preferences.
Most of my mounting experiments have been on myself. I have done this with all of my kids and a few friends, but I have not had to experiment much with them to get the feeling like they are dialed-in. I know that the PMTS crew in Summit County (Geoffda, JMD, SteveS) regularly experiment with binding position when they swap skis, but they haven't been actually tracking the data like I have with my own quiver. I still have close to 30 skis in my house and I started investigating binding mount location options in 2004. I'm still not 100% sure about the mounting position using the boot midsole over the narrowest point of the ski. It's still very early in my research and I cannot guarantee that it's a fail-safe method yet, but the more people that are involved in the experimentation and reporting back with their data, the better. -
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I don't think the comments on women's skis are entirely fair. In some cases, yes, there are some manufacturers who make lightweight intermediate level skis, put on a prissy topsheet and market them to women. But then there are unisex skis of similar performance in their line as well. In the past 5 years most have been making serious skis for good female skiers. If you've ever picked up and flexed a Volkl Aura or Kenja, you'd know what I mean. Those are serious, stiff, high performance boards that most men would be challenged on. Ditto skis by Nordica, Dynastar, Fischer, Elan.... In fact, almost the entire Dynastar women's line has long been of excellent quality, with only the minority of models being of intermediate level. Not sure about Head these days - I haven't checked out their new Mya line (although the just the name is kind of girlie), but formerly they had some real powerhouse women's skis that were the equivalent of the top range unisex versions -- Power One = Supershape Speed; Wild One = iM82; Great One = iM78....you get the picture... To imply that they condescend women's athleticism and skiing ability doesn't seem to be accurate at all -- in fact I think the opposite is true, and there is a wealth of choice for skilled female skiers. And if there is nothing that suits, then a woman has the entire range of unisex skis to choose from.
HA - your comments on ski flex pattern I think are quite valid. I thought of saying it yesterday, but didn't want to over-complicate the discussion here.
All-in-all, you're undertaking a very interesting experiment. I'd be happy to volunteer to be a lab rat, or at least offer up our family quiver (8 pair) for the sake of scientific advancement of a worthy cause. Need data? Just send a digital caliper calibrated to NIST standards and I'm your man.
Seriously, I'd be happy to forward you some numbers. Let me know...send a PM if interested. BTW, most of the pairs in this household are skied by females, if that would help balance out your dataset.
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Svend - As noted in your correction, binding delta and boot ramp angles clearly impact fore/aft balance. It's a system; boots, bindings, and skis work together and if any one of those elements are not matched well to the skier then the performance will suffer.
Quite so. I'm glad I thought to revisit my review of the Stormriders and correct that statement, as the setup with the riser plates under the toe pieces of the bindings was certainly unconventional. If I recall, they were close to 1 cm thick. Not sure what the rationale was behind that in the context of the skier/owner of the Stockli's, but there must have been a good reason for it based on his stance or anatomy. All I know is, that it certainly did not agree with me, and the owner of those brand new skis seemed to feel the same. He was fighting them all day.
I recall some discussion here about reducing binding ramp in order to push the hips forward; a rather counter-intuitive thing. Well, if that's the solution, I can't say much for it. The combination of reduced ramp and BoF/CRS mount point was a failure in my estimation. If nothing else, this reinforces your point that stance does have an effect on mounting point.
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I figured I'd meander over to post in this sticky topic. I wanted to make sure I wasn't dismissing HA's efforts based on my comments elsewhere.
I will say, I am extremely picky about mounting point. I use the BoF method to give me a starting point with my mounts, and usually move from there based on the feel of the ski. Mounting point is extremely personal, and sometimes 1cm can be the difference between liking and not liking a ski. It is important to keep this in mind... but I will admit that I don't put a lot of "math" behind my selection. I get close, and do the rest by feel and observation with video. -
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^^^^^^ Absolutely agreed. My intention is to find a great starting point and experiment from there when necessary. However, I love being able to "nail it" from the get go. Sometimes that happens, sometimes not. I'm continuing the research to better understand how the data relates the position on the ski.
Skied my new Scott Neo skis today and I have to admit - nailed it. I feel absolutely no need to further experiment. This was a ski that perfectly matched the narrowest point of the sidecut to the center of effective edge, so I had a strong feeling that the position would feel dialed from the get go. -
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Interesting technical topic - I like it. I've played around a little bit with binding position but I've never figured it out. For those of you who have experimented: what does a binding mounted too far back feel like to you? How does a binding mounted too far forward feel like?
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Smackboy, my experience with this has been...
Bindings too far back: shovels difficult to engage; feel the need to get body way forward over the tips to get the skis to respond to tipping movements; ski tips are skittish or flappy at high speed (unless body is way forward and skis evenly weighted); skis hard to control in crud / broken snow (ie. shovels easily deflected).
Bindings too far forward: whole ski feels skittish and hard to control, like skiing on marbles; very poor edge engagement; tails wash out under pressure in a turn.
Others may have further insight, but the above are what I have felt.
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I agree with Svend on his observations for bindings mounted too far back. For bindings mounted too far forward I would like to add that I feel like the front end of the ski is "overloaded" - it's very difficult to get it to disengage and as Svend noted, the tails easily wash out. I accidentally did a too far forward mount on a pair of old K2 Enemy skis many years ago and it wasn't a pleasant experience, but what it did show me is that a ski that had absolutely no edge hold to speak of suddenly felt like a scalpel - maybe just a tad too sharp though.
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