ZEPPA-DELTA ANGLE EXTENDER


The problem associated with measuring boot board (zeppa) and/or binding (delta) ramp angle as individual components is that the resulting angle may not accurately reflect the actual angle between the plane of the base of the upper surface of the boot board and the base of the ski in the boot/binding/ski system. Boot boards of the same zeppa angle may not necessarily have the same zeppa angle with the base of the boot shell due to design and/or manufacturing variances.

A level inserted into a ski boot shell with the boot board in place can be difficult to read. With the liner in place, this is not a viable option. A better option is to extend the angle of the boot board up above the top of the shaft of the boot so it can be accurately and easily read.

A simple device for this purpose can be made for about $25 with basic hand tools and a few screws using 2 – 8 in (20 cm) x 12 in (30 cm) x 1/8 in (3 mm) thick steel carpenter’s squares.

Place the long arms of the squares over each other as shown in the photo below and clamp them securely together. Two-sided tape can be used to help secure the alignment. Then drill a hole  at one point on the vertical leg and screw the 2 squares together.

Check the parallelness of the 2 opposite arms on a level surface with a digital level. If good, secure the 2 levels together with a second screw. Then affix a section of 3/4 in (2 cm) x 3/4 in (2 cm) square or L-bar bar on the top of the extender to rest the level on.

To use the extender, place a boot shell on a hard, flat, level surface. If the surface is not level it should be leveled before the extender is used.

The photo below shows the extender being used to measure the zeppa angle of an old Salomon SX-90 shell. I didn’t have the electronic level for the photo. So I used a small torpedo level.

Insert the lower arm of the device into the shell as shown in the right hand image and place the lower arm firmly on the boot board. Place the level on the top arm and read the angle.

The photo below shows the same process as above. But in this example, the liner is in place. If an insole is in the liner, it should be flat with no arch form. I highlighted the square bar with pink to make it easily visible.

A check of the zeppa-delta angle of the boot-binding-ski system can be done by mounting the boot in the binding of the ski that is part of the system and clamping the ski to a flat surface with sufficient force to ensure the camber is removed and the running surface of the base is in full contact with the supporting surface. A strap wrapped over the front of the boot shell and under and around the supporting surface then tensioned will help ensure that the toe plate of the binding is loaded.

The Zeppa-Delta Angle Extender provides the user with a fast accurate way to know their total number. What’s yours?

 

6 comments

  1. Hi David, just to share my own experience on ramp angle measurement. My sole has at least 3 subsection with different angles (at the heel it is almost flat, main angle is in the middle and front is almost flat again). Trying to measure angle with a carpenter square or even a small smartphone with a level application seems not to be working on my side (too difficult to make sure both end of the phone or square are applied at the right location inside the boot and not on the flat surfaces) and what seems to be aligned with vendor datas is to measure heidth at heel main pressure point, at ball of the feet pressure point, distance between those 2 points and apply a trigonometric formula to get the associated triangle angle. What do you think and what is your experience from that perspective ?

    1. The problem as I have alluded to many times is the apparent lack of a standard in the industry. Boot board design and construction can and does vary greatly. This issue aside, there can be problems with instability of boot boards in the receiving well in the bottom of the shell.

      When the design and construction of a boot board permits, I plane and/or grind the long axis flat (monoplanar) and ensure the transverse axis is parallel to the boot sole. Even if you manage to calculate the ramp angle of a multiplane boot board, there is no guarantee that it will have the same effect on the foot as a monoplanar boot board even if the ramp angles appear to be the same.

  2. Hi David,

    Thanks for this idea. It will make my measurements easier and more accurate. I would suggest to also bevel or round off and smooth the three corners of the lower leg to protect the liner when inserting the tool. If using a shaped insole of any kind, one would have to adapt the lower leg of the tool to contact only the heel and the metatarsal (ball) area on the insole. (Please correct me if this is not correct, David). Equal thickness pads at the appropriate spacing as measured on the insole and placed at the lowest points at ball and heel perhaps?
    I had to do that myself since my boot board had toe spring( non removable boot board).

    A giant double second of your shout out to the ski industry. It would only take one of them to proffer a disruptive technology employing real research data on ramp angle and biomechanics to scare the others into doing the (hopefully) right thing.

    Thanks again David,
    Herb

    1. Hi Herb,

      Thank you for your comments.

      Yes, definitely round off the 3 corners (top and bottom at the toe end and bottom at the heel end).

      “A giant double second of your shout out to the ski industry. It would only take one of them to proffer a disruptive technology employing real research data on ramp angle and biomechanics to scare the others into doing the (hopefully) right thing.”

      Part of the motive behind my strategy to come up with simple, low-cost tools to check things like zeppa-delta ramp angle and optimal stance ramp angle is to make it difficult for the industry to ignore these issues. As things like optimal zeppa-delta ramp angle become recognized it will be harder and harder for those who are profiting from services and products to not do the right thing.

      “If using a shaped insole of any kind, one would have to adapt the lower leg of the tool to contact only the heel and the metatarsal (ball) area on the insole.”
      Yes and no. You are correct that could support the load points of the foot on discrete pads. But placement can become an issue. As I’ve said many times, there is no standard in the ski industry for boot boards profiles or ramp angles. There are also significant issues in some boots between the boot board and shell shelf on each side as well as instability. One solution I am playing with with an associate is cast in place boot boards or cast over existing boot boards using a material like Smooth On 385. It is still early but results so far have been excellent. If you are going to err it is better to err on the side of not quite enough in terms of height than too much. You can always pour additional layers on top.

      https://www.smooth-on.com/products/smooth-cast-385/

      You seem to have some good ideas. So please pass on anything you come up with that you would like to share.

      Best,
      David

  3. Hello David,

    I have been reading the post’s regarding Zeppa-Delta angle and stance training with interest. I have taken it upon myself over the past few seasons to become more informed and implement changes to my boots on my own. A few issues that I have had to address relate to liner fit and cold feet, but my current main focus is stance and balance and boot forward lean.

    With stance training over this off season I will see if I can develop a ‘new’ norm and compare it to my current alignment, couple this with Zeppa measurements and possible modifications. A question that come to mind is the boot shell modification and how to accomplish this. The stance training will develop the lower leg angle – I’ll assume that the desired upper cuff angle/location would be the result of this stance lower leg angle. How is this modification best achieved?

    Regards

    Stephen

    From: The Skier’s Manifesto Reply-To: The Skier’s Manifesto Date: Wednesday, March 21, 2018 at 7:46 PM To: Subject: [New post] ZEPPA-DELTA ANGLE EXTENDER

    skikinetics posted: “The problem associated with measuring boot board (zeppa) and/or binding (delta) ramp angle as individual components is that the resulting angle may not accurately reflect the actual angle between the plane of the base of the upper surface of the boot boar”

    1. “The stance training will develop the lower leg angle – I’ll assume that the desired upper cuff angle/location would be the result of this stance lower leg angle.”

      Correct. Stance training identifies the forward and rearward reference end points of low resistance of about 12 to 14 degrees of shank movement (ankle flexion) which should occur within the confines of the structure of the shaft (cuff) of the boot. Adjusting the forward reference which is defined by contact (not aggressive) of the shank with the tongue, can usually be achieved with upper buckle/power strap adjustments. Depending on the cross sectional area of the calf muscle at the top of the shaft of the boot, the rearward reference can usually be achieved by adding or removing spoiler shims. But achieving the correct reference for skiers with large calfs muscles can require extensive modification of the shaft and lower shell.

      “How is this modification best achieved?”

      I will describe these issues in future posts.

      The essential first steps are 1) stance training, followed by, 2) identifying the optimal zeppa ramp angle (delta zero). This is an issue where the ski industry appears to have been and continues to be asleep at the wheel. I have said it before and I will say it again; the industry needs to conduct some serious research on this issue or, better still fund some unbiased serious research on this issue – NOW.

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