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EpicSki › Gear Articles › Ski Binding Placement Fore Aft

Ski Binding Placement Fore Aft

Marmot mb poses the following question:

Given a ski that is 85 - 90 mm waist / 115 - 120 mm tip / 110 - 115 mm tail / 178 length,

1. What effect should and would having a binding rearward of the default mounting position have:

  • In Powder?
  • On Hardpack?


2. What effect should and would having a binding forward of the default mounting position have:

  • In Powder?
  • On Hardpack?

 

HeluvaSkier

 

I would like to describe this in terms of where your CM is in relation to the sweet spot of the ski, when you are in a normal neutral stance (not forward or back).

Normal Mount: In the above position your CM is at the sweet spot.

Forward Mount: Your CM is ahead of or toward the front of the skis sweet spot.

Rearward Mount: Your Cm, in a natural position is toward the back of, or behind the skis sweet spot.

Most of you probably already knew that. Now the question is: How do you ski each of these setups, and what might they be good for?

The normal mount is of course the recommended position on all skis. This is typically the best position for a variety of conditions (powder, park, groomers, edge to egde quickness, etc). I find this to offer the most versatility on a ski. Msot expert skiers know how to move their body position so taht their CM hits different parts of the sweet spot of the ski. The skier will do this based on terrain they are skiing, and point they are in a turn. If you ski one terrain or do one type of skiing exclusively, you may want to specialize your skis to one of the other options. Being a racer, on all skis, regardless of type, I feel more comfortable on groomers when I am mounted in the proper position. I'll get to why in just a few lines.

A forward mount obviously decreases the amount of tip in front of you. Naturally this is great for creating equal swing weight for your skis, and makes it easy to land large drops/jumps and not end up on your back side. In tight places the skis will tend to hang the tails up on terrain features. Also, if you ski these skis too far froward, you will end up lifting the tail off the snow, so you rarely will see a rider skiing far forward on this type of mount. This is why I don't usually enjoy this mount on groomers. If a backseat driver were to get on the skis they would love them, not because they would fix how they skied, but the rider would now be over the sweetspot, even if they were still skiing in the back seat.

A rearward mount is something that I have only heard of in recent years. I have heard of it on powder skis most recently. This mounting position is great if you have NO problems moving forward over your tips. To get yourself over the sweet spot on the ski you have to always be up over your tips, or if you are working the ski in a freeride type situation, you have to be able to move back and forth over the ski, but if you get in the back seat... you better be able to get over the tip. This would be fun in powder - if you werent catching air. If you start dropping cliffs, you may want to get more tail behind you so you arent burying yourself or slapping the snow on every drop. With a short tail in powder you can easily sink the tail and use slight rotary to "break" and slow yourself down, but again you will have to move yourself forward again or you will constantly be fighting staying up near the sweet spot. I have also heard of similar mounts to this used in SL racing, but that is slightly off topic.

 

manus

 

One major thing to consider that most people never think about is where is the center of the sidecut. Often times the center of sidecut (narrowest point) is a little in front of the recomended mount postion. From my experience, I prefer a slightly forward mount, 1-3 cm in front of the recomended mount point (on my K2's) and while there has been occasionally (VERY rare) a tail grab, its has been so rare that it wasn't enough to discourage me from mounting there and I found the ski much quicker turn to turn. However, on skis where the mount was more forward (around +5cm), 4FRNT and Pistol, I noticed what I described as to much tail, the skis didn't feel like they wanted to turn properly and felt like they wanted to bury the tips (even in around a 180 length).


Now, on my Fischers, I can move the binding about +/- 1.5 cm from neutral, and on those, the forward position felt foreign, I could feel the shovel, but it just didn't feel like it wanted to engage. However, on the neutral point, it felt very under foot, and not very forgiving to fore/aft adjustments, however in the aft mount position, the ski felt much more forgiving and just as capable. Comparing the Fischers (Rx8Fti railflex) to the K2's (PE's), I think the biggest difference is where the sidecut is located, sidecut center felt underfoot on the Fischers and Forward on the K2's. Personally I think its more important to match up the sidecut center and mount point (to your preference of CM location - I like the sidecut center under/near the ball of my foot).

Now in terms of how they ski, with a forward mount, you have less leverage to engage the shovel, thus you need to actually be more forward to engage the ski properly (this seems to disagree with previous comments). With that said, if this is a powder oriented ski, this need to be more forward also then means the ski should be longer (to prevent the feeling of tip diving) to allow the tip to float. On some skis, you may be more prone to "feel" the tail during turns (it may feel stiffer because of the slightly longer effective edge behind the heel), and if that is the case, often times, people will lean back relying on the tail to ski (which is innefficient, although does work).

Now, these examples are somewhat different from racing applications. If you are racer and attack gates (more forward skiing) a forward mount can be beneficial, somewhat seemingly shortening the ski, allowing quicker turns. Conversly, if you are a power racer (really driving by the tails and using strenth and the strength of the ski to propell forward into the new turn), a slightly aft mount can help by providing more length in front of the toe, potentially engaging the shovel better into the new turn (with the aft->fore explosion between turns).

Now, park specific mount point adjustments are a different scenario again. Moving forward helps to center the swing weight for spins, and helps to "center" balance on rails/boxes. Also, a forward mount adds tail length (obviously) which can help when landing slightly aft, skiing out from a jump, instead of bailing. Also, the forward mount (often as far as true center - typically about +7.5 cm) aides switch skiing, making the regular and switch turns more equal.

 

Noodler

 

Great posts so far. This is really a huge issue and there's a ton of good info on this (especially at Keelty's site realskiers.com). The most important fact to come away with is that the mounting point (midsole mark) may or may not be the best place for you depending on the ski manufacturer and your body stature. I've found that for me I'm much better off using the BoF (Ball of Foot) method for determining a better mounting point (at least as a starting point). All of the already mentioned issues regarding sidecut, waist width, and ski flex will also have an effect.

I still hold a major belief that one of the reasons you sometimes see wildly varying opinions on skis is completely due to the mounting position and the body types of the reviewers. I wish every binding made it easy to adjust the fore/aft position, not only to adjust for body stature, but also to adjust for snow conditions. I'd like to see these adjustments go beyond what we have available today with only a few "static" positions available (Atomic, Tyrolia). I'd like to have much more granular adjustments available.

 

Determining BoF mounting position

Tools needed: Tape measure (I have a metric one), two 6"+ straight edge rulers, pencil, screwdriver, pen, marker

Here is the method I use:

  1. Determine the running length (contact length) - put the ski flat on a fairly level floor. Slide a "straight edge" between the bottom surface of the ski and the floor at the tip of the ski. Slide it in until it is stopped by the contact between the ski and the floor. Repeat for the tail with the second straight edge. If the ski has a ton of camber you may need to press it flat against the floor before doing this to ensure you are getting a true contact length measurement. I like to use long straight edges for this so that I can take the contact length measurement on both sides of the ski to double check that I have positioned the straight edges properly. That's why I prefer to use longer ones that stick out on both sides of the ski. Some people use business cards (or credit cards), but I find that my small steel rulers give me better results. Measure the distance between the "contact" points to determine the true running length and mark the contact points on the ski with a pencil (both sides!).
  2. Determine the BoF position - Divide the running length measurement in half and mark this position on both sides of the ski with a pencil. This position is where you want the ball of your foot to be placed.
  3. Find the midsole mark on your foot - I use a slightly different method for this than you'll find in other places. I've found that the arch of my foot is much more sensitive than the ball of my foot. I place my bare foot in the shell with my footbed (the footbed is positioned approximately where it would normally end up in the shell). I then tap the outside of the shell at the midsole mark with a screwdriver and take note of where that point is hitting my arch. I then mark that point on my foot with a pen. To double-check my mark I then use a marker to place a mark on the inside of the boot that corresponds to the midsole mark on the outside of the boot. (You kind of have to come up with a method that will work for your boot. My Flexons and Krypton allow me easy access to this section of the boot so it isn't that difficult). While the mark on the inside is still "wet" I put my bare foot back in the boot, make sure it is lined up properly, and then press it into the side of the boot. This transfers the marker line to my foot. I then checked that the ballpoint line (determined through tapping) and the marker line (determined through a visual line-up) match fairly well. If they don't something is screwed up.
  4. Determine the distance from your boot midsole mark to the BoF position - Now that you have a midsole mark on your arch you can measure the distance to the ball of your foot. This certainly isn't exact science, but I just place a ruler on the floor and with my foot ON THE footbed I measure the distance from the midsole mark on my foot to the ball of my foot. For me this measurement is a nice even 60mm.
  5. Mark the "new" midsole mark on your ski - With the measurement from the midsole mark to the BoF determined from the boot, mark the new midsole mark on the ski with a pencil. Measure back from the BoF mark on the ski and make a new midsole mark.


With my Volkls this new midsole mark was always about 30mm forward of the factory mark. On my Stocklis it is about 20 mm forward. Surprisingly, on my new Elans it's right on the factory mark.

 

These are the midsole mark adjustments I calculated for each of my skis:
 

Brand

Year

Model

Difference

Elan

2005

S12

0.75 cm

Elan

2006

M666

0.85 cm

Stockli

2005

Stormrider XL

2.20 cm

Stockli

2004

Stormrider DP

2.50 cm

Volant

2004

Machete FB

-0.50 cm

Volant

2004

Machete Sin

-0.15 cm

Volant

2004

Machete Soul

2.15 cm.

Volkl

2003

T50 5-Star

2.50 cm


Positive values indicate that the midsole mark should be moved forward, negative values rearward. It's interesting that the Machete Sin and FB manufacturer marks are actually too far forward based on my calculations. You may see some threads about how most people hate their FBs mounted at the suggested position - most people mount them further rearward to improve the tip float. I remounted my Stormrider XLs for this season so that they are right on my calculated mark (22mm forward). I haven't mounted the Elans yet, but I think that they're close enough that I'm just going to use the manufacturer mark (and I'm putting a plate on the S12 so that will give me some adjustment if needed).
 
HeluvaSkier

Regarding Mounts in Racing

As a disclaimer, I would say that WC racers mount themselves on the ski where they, their coach, and their ski tech feel that they are performing the best when on the snow. An interesting aside to theis conversation that I have heard of and noticed in talented racers is that they do not mind playing with the ramp angle of their bindings. If you think about it, it accomplishes nearly the same thing as moving the binding, but you are only adding or removing material from under the binding, or from within the boot. Bode Miller is a classic case of this. His boots are actually machined from the inside so that his heel sits lower than his toe. This increases the angle that his shin is at inside the boot, putting him in a more athletic stance. I do not know if this is still true to this day, but I do know that when he was using Dobermann's that he had them set up this way. I discussed this about two years ago with his team mate Erik, since at the time they were both using the Dobermann boot.

If you think about it, the ramp can make a huge difference in your stance if you assume that however your ramp angle adjusts your upper body stays in the same place. Without moving your shoulders or upper body at all, you can be given more forward pressure (ramping up the toe) or less (ramping up the heel). I experimented with this in my own skiing and found that I ski best with a flat ramp. I typically ski on Salomon bindings, which put you very far forward, so I machine new lifters for between the binding and plate that put the ramp at nearly flat, or just a millimeter or two higher in the toe. As far as obtaining more forward pressure: It works. Without moving your CM out over the tips of the ski, you can still have huge amounts of forward pressure due to the increased angle your shins are at. If you don't keep that angle however, and use the flex of the boot, it is easy to drift into the backseat... but if you are able to bring yoruself forward again you can really work the skis a lot more than with a forward ramp.

 

Bud Heishman

 

Each ski/skier has an optimum mount position and without experimenting or I should say, without having the ability to experiment, we are just guessing.

FYI, the angle created by the binding stand height differential is generally referred to as "Delta Angle". Ramp angle is the angle created by the internal boot board and footbed. These two are related but have different affects.

I have measured a bunch of next year's bindings "stand height differentials" and if there is interest I could post them here? Just do not have them here with me now.

Someone also made a comment about being confused on the affects of heel lift in relation to moving hips forward or back. Again, there is an optimum position for everyone, and finding it is a key to good fore/aft alignment and balance. As the heel is lifted it moves the CoM forward. If the CoM is moved too far forward the body will naturally compensate by moving the butt rearward to remain in balance, thus the skier demonstrates a more flexed backseat appearance. Too flat of an angle will tend to show a more extended leg position with a break at the waist to compensate for the flat angle, again compensating to remain in balance. Finding the optimum angle along this spectrum creates the desired stance and ease of balance. Remember there are four areas that affect this fore/aft positioning: ramp, delta, boot cuff forward lean, and binding position on skis.

Generally I begin with finding the appropriate ramp angle and forward lean angle for the skier's ankle rom which creates the appropriate "net forward lean" inside the boot, then checking static positioning over the ski which is determined by the delta angle created by the bindings, then optimumly, testing dynamically on hill with shims to finalize everything, then if possible, testing binding placement positions.

The goal is to find the optimum position where the skier feels well balanced without having to make any compensatory movements from the static position created by the equipment.

 

An interesting note from some alignment parameter testing done this 2009 season with PSIA instructors: The observation was made that as the delta angle increased on the ski, moving the mount position rearward would compensate and visa versa, a ski with a negative delta angle could be compensated for by moving binding forward.

I have also done a bunch of one ski skiing without the other ski on and no poles to isolate the movements necessary and found that the fore/aft alignment is critically related to the ease of skiing on one ski and the transitions to the little toe edge. The focus was to make a steered turn entry vs. a carved edge to edge transition or a pivoted turn entry. This requires very accurate movements and isolates and accurate trajectory. When my delta angle was too steep, by as little as a couple mm., I had great difficulty finding the tongue pressure needed to transition confidently to the little toe side. Once this was corrected the task became much easier!

 

We have a new binding on the market next year from Marker called the Schizo or something like that which will allow 6 centimeters of continuous adjustment with just a quarter from your pocket.  This binding will allow one to easily adjust their binding placement on the slope to find their personal sweet spot or quickly switch from park n pipe to powder with just the twist of a screw.


Lou Rosenfeld

Heluva brings up several points that perfectly illustrate the misconceptions that surround binding position and ski design.  I will add some information here and I believe somewhere in the Wikis is the research report I, Alan Schoenberger and Steve Bagley conducted on the Campbell Balancer for Nordica.  There is also more information on the Lou's website at www.lous.ca.

There is a commonly held assumption that binding position is designed into the ski, so that once the designer has finished his or her design it is already known where the mark belongs and it is also assumed incorrectly that the sidecut centre is located by this mark or vice versa.  Neither assumption is correct and each leads to many incorrect statements when we talk about binding position.  Even questions such as what is the effect of moving bindings forward cannot be precisely answered if you are talking about forward or rearward of the factory position. 

In the simplest terms the factory position is not designed into the ski nor is it simply put into the centre of the waist.  It is determined by ski testers skiing the ski in a variety of positions and then somehow determining the position from their results.  Assuming (a problem I know) that  testers are not clones, they probably have different height, weight, foot length and other characteristics.  Again I assume they are briefed by the manufacturer on desired ski characteristics and ski market etc.  I think this is a safe assumption because nothing else could account for the wide differences is binding position amongst manufacturers for basically identical skis.

An example is a racer I had in the store last week.  He has struggled for two years without making great strides in his results.  Problem was he could not stay forward in tech and found himself getting later and later and further and further back on his skis until he eventually blew out of the course when he was back to far to make the next gate.  He came to me because he was looking for boot setup problems.  I thought it sounded like a binding position problem.  Interestingly he is skiing for a new manufacturer this season (Head) and when he tested spring of last season the reason for the switch was that the problem instantly went away.  Like most of us he assumed there was no correction for binding position so it had to be something else related to luck or the interaction between his boots and skis.  When we measured relative to the Centre of Running Surface we found that his Head SLs were fully 3 cms in front of the skis he had been struggling with for two seasons.  When we balanced him on the Campbell Balancer he balanced approximately 7mm's behind the Head position.  We will test both positions but either is enough of a difference from his old skis to correct his problem.

Another example quickly if you like.  Two years ago had a female bump competitor in the store.  She was skiing OK but not really feeling the ski love.  She had skied several different manufacturer skis and always applied the same rule.  Automatically moved her bindings 1 cm forward of manufacturers recommendation.  Of course since there is no standardization among manufacturers 1 cm on a Rossi may be very different position on the ski than 1 cm forward on a Fischer.  We balanced her, moved her two cms back (1 cm behind manufacturer) problems solved.If you want to debate binding position, no problem.  Just understand that you must standardize the position.  I find talking about the position relative to the centre of running surface (CRS) works very well for me since the Campbell position is related to the CRS, before we had factory marks skis were mounted relative the CRS and at the World Cup level skis are often tested starting with a ball-of-foot (BOF)/crs mount.

To repeat, discussions and generalizations on binding position are useless if you are relating it to factory position.  I like Noodler's comments here, they will get you a meaningful discussion and our results over the years have shown that a BOF/CRS mount works well on nearly all skis in all conditions.

Finally I would like to address Bud's comments on ramp angle which I agree with in part but not absolutely.  I believe Bud is correct that ramp angle changes and binding position changes can result in similar changes in ski feel.  But I would say they come at it from very different directions and are not interchangeable.  Both should be looked at in a complete assessment.  Ramp angle affects the stance you are able to assume and on your ability to balance,  while binding position affects the stance you must assume in order to turn the ski.

Out

Lou
 

Comments (2)

Great article. I have been looking for an article like this for years. Just one comment. There is a far easier way to locate the ball of your foot in the boot and you need not remove the sock or footbed. This method will let you easily locate the distance of the back of your heel from the outer edge of the back of the boot cleat. It requires 2, 20" x 1/2" x1/2" wood sticks, or something similar. Cut about 1.5" off of one stick and hot glue it to the side of the stick perpendicular to the length of the stick. This will create a dog leg type device. Insert this stick in the boot with the tip of the short dog leg against the heel cup in the boot and the length of the dog leg should be parallel to the linear axis of the boot. Clamp the other stick to a small square or block of wood so it is perpendicular to the surface it is setting on. (Also referred to as plumb.) Bring the tip of the boot cleat to the edge of the perpendicular stick. Now, while holding the tip of the dog leg rock the stick in that is in the boot toward the back until it is parallel to the perpendicular stick clamped to the square or block of wood. Now carefully measure the inside distance between the two sticks at to points at least 5" apart. Rock the stick unti the two dimensions are identical. Write this dimension down if you made the dog leg 1.5", subtract that amount or whatever the amount of your dog leg is from the dimension you wrote down. Now take that remainder and use it to measure from the back edge of the heel cleat and mark it on the sole. Now all you have to do is measure the distance of the ball of your foot to the edge of your heel. To do that place a piece of paper against a wall that does not have 1/4 round base moulding. Place your foot on the paper and bring your heel back against the wall. Mark the ball of your foot on the paper. Transfer that dimension from the paper to the boot sole by placing the edge of the paper on the mark on the sole that corresponds to your heel position and mark the boot sole forward where your ball of the foot mark on the paper matches up. This is probably accurate to 2 mm. Its so easy you can do it again just confirm your accuracy.
I have a small typo, let me correct it here. The line should read: Now, while positioning the tip of the dog leg against the heel cup at the foot bed inside the boot, rock the stick toward the rear of the boot by holding it out side the boot until it is parallel to the perpendicular stick clamped to a square or block of wood.
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