fore/aft Balance - Ramp Angle - Delta angle - Heel Lifts etc

[John Mason]

Just in case any info that develops here is helpful to others, I've had a consistant issue with fore to aft balance. Jay stayed with me Sun night and rode to the airport with me so we had a lot of time to discuss this. At that time I decided since I had a witness, I'd rank my skis subjectively to Jay as to which were more or less comfortable for me in terms of fore/aft balance as I have felt big differences between the worse and best. Then when I got home, see if that ranking correlated to my ski's ramp angles. (some of this is repetitive as I started to hijack another thread. My apologies.)

Ends up they correlated perfectly.

I marked a spot on both ends of the boot then measured from the bottom of the boots to the bottom of the skis. All 3 pairs of skis have a positive delta angle (ramp is the forward tipping built into the base of the boot, while delta angle is the total forward tipping built into the ski/binding - not sure if there is a name for the total combined forward tilt).

Head I75m's - - 3mm
Head 1100 xrc's sw - - 5mm
6 Stars - - 6mm

(this is not in degrees, just height differences from the mark on the front toe piece compared to the mark on the tail piece.)

This is also the ranking of worse to better for me in terms of fore/aft balance management. The 6 stars are much easier for me to stay out of the back seat than the I75m's.

So, for me, my body seems to like ramp. Yet, this is all different for different people. Jay noticed that my hip to knee length is quite long while my knee to ankle is short. This ratio is probably but one of many components that go into what if any ramp angle helps a particullar person balance fore/aft. Some people need to remove ramp angle to get comfortable.

Paul (instructor at the camp from vail) and I were talking about this and he has a discontinued Dalbello boot that has the allen wrench ramp angle adjustment. He told me how even a quarter turn either direction made very noticible differences in his skiing. He also told me that the first time he got himself dialed in perfectly it was just shocking how his fore/aft balance problems went away. (anyone know how Paul is doing- he got injured the last day of the camp?)

Witherall in his book believes most of the population benefits from greater ramp angle. Yet, there are also people, a smaller percentage, that are the oppisite in that ramp angles need to be less for them to manage fore/aft balance. Bottom line seems to be that individual skeletal angles and lengths determine this and are very different from person to person. Witherall has a process to zero in on cant amounts and then to on-slope adjustment. HH as an even more detailed process (just look at the forms and measurements both parties use - HH's is much more complete).

Yet, witherall and HH both do not seem to have a systematic initial measurement system for an initial ramp/delta angle for a particullar individual. It's all trial and error. SI came up with a dual scale setup to see how much weight was on the front vs back of the boots. He tried this with 4 individuals. 2 guys and 2 females. He measured all four then increased the ramp the same for all four and re-measured. In 2 of the 4 cases this improved the balance and in 2 of the 4 cases the balance became worse. This shows two things.

1. what helps one person may make another person worse
2. SI may be onto a process that could add objectivity into initial ramp angle assessment.

Interestingly, and maybe someone can help me with this, at the whole camp everyone told me to hold my hands out in front of me, and not let them drop. But, moving my hands in front of me and holding them, for balance to be maintained, causes my body to shift more to my heels. I can feel this just standing and raising my arms forward. On the other hand, putting something to raise my heels makes it all work playing around on the wobble board. My normal weight just standing around is on my heels and it's quickly worse as any flexion is done. (probably due to my long upper leg relative to my lower leg)

Anyone have any leg ratio data - ankle to knee / knee to hip vs ramp angle? The literature seems barren other than trial and error. Perhaps SI's little test could be expanded with a set of test students and developed into a real process. I can't wait to get down to the ramp angle I need and to ski again. The difference for me skiing the I75M's with its slight delta angle vs my 6 stars which have 2 times the delta angle of the I75m's is dramatic. Yet I believe in my case even more angle will help.

[skier_j]

John,

Hope you had a good holiday!

Could you add just one piece of information to this, seems interesting to me.

What bindings are one each of the ski's listed---and were there any initial mod's done to them? Or are they mounted "Off the rack" so to speak?

[Jim Ratliff]

John:

I don't have anything to offer nearly as intelligent as what you have already written. However, since you have the Head IM75's I am really curious if you assessment of their comfort is consistent no matter which of the three binding positions you use.

My real question is whether this is an issue of ramp angle or is there a side effect of moving your center of mass forward over the skis, and does changing the binding mounting location have a similar effect?

Somewhat sorry for the simpleton question; you guys on this forum are way to knowledgeable (and maybe even too smart) for me.

[John Mason]

the 3 skis are all in their standard setups

the head I 75M has the railflex bindging

the 6 stars have the marker 1200 binding

the head 1100 have a tyroliai cyber binding

I perfer the forward setting on the I75m's. Moving them forward does not actually seem to make a difference in my personal feeling of fore/aft balance. But, things like skating with them are easier than the other 2 positions.

Obviously there is quite a difference in the factory setups. The Head I75's have 1/2 the ramp angle of the 6 stars. But, some people are negatively affected in fore/aft balance with increased ramp angle and others are the oppisite. For me, the 6 stars are the easiest for me to maintain fore/aft balance on. I would imagine ramp has a sweet spot by individual just like cant does. (I'm using ramp when technically, I understand Delta angle is the more correct term for the ski/binding input to total tilt forward angle)

[Harald]

John, what we know about adjusting, modifying or improving fore/aft balance, is what we have studied and gathered information about; only! The rest is guess work and experimentation. During an attempt to develop approaches for proper ramp and forward lean positions, we (Harb Ski Systems) did a study five years ago with different subjects all using the same ski boot. The boot you referred to, which is the Dalbello CRX.

We analyzed ten subjects with different leg lengths, ankle function and body dimensions and observed skiing and stance points statically and dynamically. We recorded the skiers on video, challenging their balance with one ski balance in a number of situations, as well as straight run, traverses and balance on all edges. We measured range of motion of dorsi-flexion, which is the biggest factor in fore/aft balance, other than the boot?s forward lean and ramp.

We discovered that limitations in dorsi flexion were indeed highly detrimental to skier fore/aft balance. Fore/aft balance can only be applied and controlled in a dynamic situation if your ankle has or exceeds ten degrees of range. A boot with too much forward lean (exceeding twenty degreees) will lock up the ankle or fix the ankle, as forward lean in the boot uses up ankle range. Forward lean and ramp locks the ankle foot relationship. This limits range of motion and balance. It?s only logical that if you stand someone in a boot that uses up their complete range of ankle movement, they have nothing left to flex with, this requires the upper/mid body to become the absorbing and adjusting joint. The over flexed ankle, also limits forward movement of the hips and backward movement of the feet.

You can make mechanical adjustments to enhance forward balance capability, at the points that change the fore/aft relationship. These are at the ankle, in or out of the boot, binding or ski. This requires much testing, this kind of testing takes time with a skier both on snow and indoors, for adjustments involving either binding lifts or toe lifts. This means a skier needs to be ready and really serious about fore/aft balance improvement, as it takes a number of days, a tool/work shop and a trained ski technician that has skier evaluation ability, all in the same person. This is costly, but for some skiers it is the only valid way to find solutions. Obviously the skier needs to have the motivation and the money to go through this intense diagnosis and adjustment.

I think Si has wrestled with this dilemma for years and I?m not sure he has found solutions for this problem. I know of no credible instant solutions. I have yet to see anyone produce the positive formula. We formulated one for the Dalbello Boot Company based on the adjustments available in the CRX model, which they published in their boot hand book.

With Harb Ski Systems, we have addressed this problem on a number of levels, in a systematic way, but as I stated earlier these ways require intense one-on-one experimentation. Some of the options are delta changes, both out side and inside the boot, as I suggested to you last week. I have done this with numerous skiers and to a degree, we had positive results. I can?t say we have the miracle cure, as many skiers have other than mechanical limitations holding their fore/aft balance back. Other reasons for back leaning, involve fear of forward movement or weak or underdeveloped hamstring, abdominal and erector spinae muscles. A rearward stance looks mechanically limiting, but is it related to not only the right combination for forward lean and ramp; it could also have to do with resistance to aggressive movement, fear of moving the body downhill and limited body in space awareness.

[John Mason]

I did find it interesting in that my subjective feeling with my skis correlated to their ramp angle. The difference between my best and worse ski is huge. Your suggestion of 3 more degrees as an experiment from the camp is one I'm ready to try.

I sure wish Dalbello still made that boot. That would make this a lot easier. Paul had a pair of these with the allen wrench heel adjustors at the camp.

In the mean time, I'll work on my flexiblity and core strength so by Dec when I'm back out there I can be ready to play with this. Whatever combination of me or the equipment I'm ready to get it nailed.

My goal, get the fore/aft thing figured out by the all mountain camp.

Thanks for an outstanding instructor camp!

[John Mason]

Actually - looks like many boots in the Dalbello line this year have the heel adjustment allen wrench back.

Looks like the Z-tech and the Innovex, visio, lines have it, but not the new krypton.

Would this be worth looking into?

[ydnar]

John,

You are using the term fore/aft balance. I want you to think about the idea of fore/aft alignment. If you get the fore/aft alignment right then you don't have to make any extra moves to get the fore aft balance right.

yd

[Haral]

Skiing at levels where the skis are carving actively will always require movement of the feet from behind the body/hips at the top of the turn, arc or High C, to forward of the hips at the end of the turn. This movement is the slicing movement of the skis going forward through the arc they are cutting. Moving the hips forward or downhill in the transition and high C part of the turn is one of the techniques we try to apply to the upper blue levels and black level skiers in PMTS at All mountain and race camps. We begin this process by introducing inside foot ?pull back? at the green blue levels. This involves re-centering on every turn.

If you make the analogy of the upside down Metronome that?s how the feet move relative to the hips, but with arc or half circle, not just a side to side pendulum.

The perfect centered position is static and will limit your progress, as that skier will assume anything moving forward, like the skis is detrimental or out of balance, yet if you prepare to re-center and move ahead of the skis you will never feel the skis are running away. The ideal turn moves the Center of G with the skis all the way to the falline. PMTS is a system where skiers are taught to prepare for what?s ahead in movement, not for what is in the moment.

[SkierSynergy]

Hey John.

Having seen you in equipment, it coulld be a function of the ratios between your lower leg, upper leg and torso length.

You had noted that you have a short lower leg length in relation to your upper leg.

Harb Ski systems had done a sysematic study of skiers all using the same Dallbello with adjustable flex, ramp angle, and forward lean. They made systematic adjustments finding the best fore aft balance for each person and then noted some sytematic findings about the process.

They found that the taller and longer legged people tended to need more ramp angle (or delta angle).

The issue is very common sense when you think about it. The lower leg tends to be more fixed in it's ability to change fore aft angle when in ski boots. Therefore when someone with a longer upper leg length (either because of a longer upper/lower leg ratio or just longer legs in general) flexes, the more their mass will tend to tranfer behind your balance point (overhang) as you flex. More forward lean will seem like an immediate solution, but it often just makes things worse. Just play a little with a stick man and you can see why?

In these cases, given a preset amount of flex (or forward lean in the boot), it will be a consistent fixed amount that you will be back. Rotating the whole system forward (clockwise) until you are in a balanced position is the solution.

I don't think anybody has looked at things like a comparison between Ramp versus Delta adjustments or how limited dorsiflexion also affect fore aft balance, but I am sure these wouold be important questions.

[John Mason]

just the fact my 6 stars are so much easier for me than my head I75's gives me hope that playing with ramp angle will make a big difference.

But, just in case, I'll get my core strength up the next notch too. Gotta be ready when I find the center of my pendulum.

[John Mason]

John,

You are using the term fore/aft balance. I want you to think about the idea of fore/aft alignment. If you get the fore/aft alignment right then you don't have to make any extra moves to get the fore aft balance right.

yd

Yep - that's what I'm going for. Find my fore aft alignment sweet spot. See you in March I hope at deer valley!

[piggyslayer]

Hi John, everyone.

This is again a great learning thread. The subject seems to be close to my heart as my wife ?chicken? is looking for fore-aft balance improvements.

Jeannie Thoren has been advocating heel lift for women for many years.
Here is her website http://www.jeanniethoren.com/
In particular, she sales heel-lifts for women. Her argument (see the link) is that typical woman body has more weight in the back and requires a little push/lift to be fore-aft aligned. In addition women tend to have history of walking in high heels so they are quite familiar with balancing with the heel lift.
I never was certain if heelifts are good or bad and was concerned with destroying lateral boot characteristics, but I guess for some people this may be what is required.

I would love if people comment on Thoren?s theory.
John, good luck with you fore-aft experiments, please post if you find evaluation method that works for you.

[woverineNorb]

John : I recently tried on both the ZX Supersport and the V-Tech from Dalbello. The ZX is the model that has the adjustable ramp angle. When I tried on the ZX by itself it felt fine, until I tried on the V-Tech simultaneously with the ZX. The difference in the ramp angle was enormous even when the ZX was set at it's lowest point. I felt pushed forward to the point of teetering on the foot. At least for me that eliminated that boot. I finally purchased the V Tech. I felt more flat footed in the footbed of the boot, more centered actually. The V Tech has a slew of adjustments from a 3 position forward lean as well as the usual cant adjustments etc. As you have astutely pointed out what is good for some may not be for others but, this is just FYI in case you want a sense of how the boot feels.

[Harald]

We no longer sell those models becasue they are too wide, soft and the geometry has changed taking them out of the lateral boot category.