When I published my first post on May 11, 2013, A Cinderella Story: The ‘Myth’ of the Perfect Fit (https://skimoves.me/2013/05/11/the-myth-of-the-…sive-perfect-fit/), I had just finished an intense, sustained cognitive effort in the development of a new footwear technology that a cycling shoe called Kinex is based on. The process reinvigorated my passion for leveraging human performance and served as the impetus for me to look critically at issues affecting skier performance. Those who are interested in cycling can view the Kinex shoe at http://www.kinexsystem.com
The philosophy behind Kinex, one that I embrace in my blog, is that the guiding principles are to use pure applied science, intense research protocols and systematic design processes to grow the understanding of how lower limb function can be improved for athletes in modern sports. The link to the page on Kinex Research & Testing is http://www.kinexsystem.com/research.php
When I started this blog, I knew that the odds were great that there were others out there who were working on some of the same issues that I had been working on since the mid 1970s. One of the key issues I was trying to clarify was the effect of ramp angle, especially Net Ramp Angle (NRA), on skier performance. Since my first post, I made two valuable connections that have served to greatly improve my understanding of this issue. I made one connection with an American (Michael) and one connection with an Italian.
Here is Michael’s latest insights on what I now regard as the most critical aspect of skiing.
ON THE TRIALS AND TRIBULATIONS OF RAMP/ZEPPA ANGLE
I’ve been intently working on this subject of ‘net ramp angle’ (NR) for many years because I thought it was the cure-all for everyone’s skiing issues. I’ve been skiing on an adjustable delta device for close to 15 years. I’ll mix in my evolution on this topic to hopefully illuminate the pros and cons of the ongoing discussions.
Here are definitions the way I understand them;
- Ramp or drop as it is referred to in shoes: the angle one is standing on in the ski boot in relation to the base of the ski.
- Delta: the angle between the point the ski boot rests on created by the difference in height between AFD on toe piece and the heel piece of a binding (this angle changes in degrees as the bindings are adjusted for larger and smaller boots)
- Zeppa: the angle of the boot board that sits into the bottom of the ski boot. (I believe this angle changes with the boot size of the same model.)
Net Ramp Angle (NRA): the sum of these three items is what really counts.
Don’t mix up degrees of delta with the height of the binding toe and heel as measured from the bottom of the ski. When placed on the same binding, a shorter boot, built to the same specs as a longer boot, will result in a steeper delta angle for the shorter boot because the binding heel and toe are positioned closer together. The reason I measure the distance from the bottom of the ski is because the ski is thickest in the middle and tapers towards the ends. So where one places the midpoint of the boot in relation to the center of the ski changes the delta. A forward position of the binding increases delta because the heel piece becomes higher in relation to the base as the ski becomes thicker. As the toe piece moves forward, the ski gets thinner. Moving the whole binding rear of center lowers the delta because the effect is the opposite. This is my argument why moving the binding forward helps some people ski better because it is minutely increasing the delta which may be what they need for the way their boots are set up. As David says, minute changes in NRA can have monumental effects on skier performance. As far as I can determine, because of the binding DIN standard, the zeppa is made to same height in relation to the boot sole for all boots instead of at a specific angle for that model regardless of boot length. This has to be recognized and compensated for during the fitting process which David clearly has stated in his blog.
Teaching skiing back in the last century I found most skiers were in the back seat. The really good skiers were over their feet. I saw a correlation between fore/aft balance and the ability to function athletically on skis. So I ‘knew’ back then if I could solve the NRA issue everyone could ski better! The Athletic Skier, printed in 1994, discussed this and promised that a major binding manufacturer would soon have an adjustable binding to deal with this issue. So as I waited, I learned that one could get skiers forward by placing heel lifts in their boots. I taught with a pocket full of heel lifts. If a skier was locked on their heels and was interested, we would zip into a lodge and throw in a pair of heel lifts. Everyone moved forward, but about 25% didn’t like it at all even though to me they looked better balanced. They said they had more difficulty turning. So we removed the heel lifts. This puzzled me greatly. It wasn’t until many years later I understood the reason skiers couldn’t turn as well was that the heel lifts lock up the skiers feet even when they seemed to have better fore/aft balance. With the Load Transfer Test, one can figure out if a heel lift is helping or hindering before going skiing. Note: I have found that anytime one places only the heel on a ‘ramp’ the foot loses mobility so I don’t use them for that purpose anymore.
Some skiers, especially those with a short torso and very long femur, couldn’t fit enough heel lifts into a ski boot to position them in a comfortable fore/aft position. I started removing the riser plates under the toe pieces of the binding or placing plastic pieces under the heel of the binding and raising that up. The major problem is it is really hard to find screws that are long enough plus the hunt starts all over if you didn’t guess correctly the first time. I believe the longest binding screws I can buy currently are only 16mm. There is a possible solution which I’ve considered, but have not tried, which is to install inserts (like snowboards have) in the skis and then use machine screws cut to length if necessary and don’t want them sticking out the bottom of your skis. Plastic is easy to purchase or find in cutting boards, old or current credit cards etc.
Here is my disclaimer on bindings; there is actually quite a bit of ‘play’ allowed in ski bindings which is evidenced when some one clicks in successfully in spite of having a block of snow/ice on their ski boot 1/4″ or more thick. Use a bit of common sense and if anything looks stressed then back off. I once had a purchaser of my adjustable plate NOT release during a fall. The ski shop immediately blamed my device (their new bindings). But it turned out that it was from a poorly done boot sole grind for canting. Many shops take only a few swipes of 1/2 degree each sole material from one side of the boot with each pass without plaining across the whole bottom of the boot leaving it v-shaped. This skier was then given a new pair of boots without an explanation. I’m totally opposed to boot sole canting of this type. Note; after having been ‘professionally’ canted in the past (to 3 degrees at one time) without a foot bed/orthotic and using Manifesto boot fitting methods, I no longer use cants at all!!! I also feel safer in a binding I have adjusted for NRA than one that leaves me completely out of balance. That to me is the real liability issue
One of my friends who could never seem to get forward enough as the years dragged on with no revolutionary bindings coming to market said, ‘why don’t you build this device yourself?’ Not being the sharpest knife in the drawer I did. I’ll skip the gory details with two comments before I talk about results; 1) There is a lot of money in patents; if you are a patent attorney. 2) You know your patent has passed when your mailbox fills up with advertisements for plaques commemorating your patent which you can buy for hundreds of $s. My device, which I call the BalancEnhancer (BE), is a plate which mounts between the ski and binding and has an adjustment mechanism on one end which can be mounted with the adjuster to the front or back. This ‘cure all’ actually worked (!) getting me over my feet which relieved so much torque on my bum knee that I could actually hop from one mogul to the next if I so desired. In my own use and with anyone else willing to try it, we needed to have a NRA up to 10-12 degrees. At that time, I had foamed injected liners and rock-hard-in-the-arch footbeds which gave me great balance statically in race fit ski boots. With this combination, I needed a ridiculous NRA to correct my fore/aft balance. I endured a couple brushes with frost bite and damaged nerves in my toes from that style of boot fitting. I’m totally opposed to this barbaric method today and now have the warmest feet ever with less liner.
Life was good until I returned to ski the steep bumps the following year and found that I couldn’t get an edge with my left foot. I finally figured out my left foot was immobilized within the ski boot compared to my right foot. I solved that issue by first removing the zeppa and then changing to a different brand ski boot based upon the zeppa (whole different dissertation). Then I found that I HAD TO LOWER the delta! Let me repeat, as I dropped my heel within the ski boot I HAD to drop the NRA, because the increased mobility in my ankles allowed me to get out of the back seat. I found that was too far forward at that setting. Leaving out a lot of detail, I currently ski with binding toe and heel pieces at equal height from the base of the ski or the with the toe up to 1/8” higher. I am not quite sure if that is due to ski construction, terrain or the position of the moon (or my mind) on a given day, but I even have fine-tuned one pair of skis with strips of duct tape. If I had learned about freeing the ankle glide path earlier, I probably would never have built the BE. Unfortunately I didn’t time my inventing of the BE very well with the advent of track bindings. So no ski company was interested. If they were polite, that’s what they said and some more things I don’t need to repeat. I would hate to see the state of the ski industry if they weren’t so open minded! A factor they ignored was that the track binding/ski combo still don’t flex as well as an un-mounted ski does whereas the BE isolates the boot and binding from the ski and allows a pure flex so I’d think at least racers would love it.
Due to the integrated bindings and very few flat skis, I had a marketing problem. Then I was asked by a co-conspirator why ski boots have a ramp to begin with. I never thought of that. So during the 2000 mile drive home, I pondered that question. I took a pair of boots (the ones with the wrong zeppa) and removed all the ramp angle. I took a pair of other ski boots that I had, cut the toes off, filed them to fit under the toe of the boot to zero out the ramp, and went skiing. Worked unbelievable until I got to steep bumps at which time I needed to increase the NRA with the BE. After that, I built a machine that I could precision grind toe pieces out of plastic (cutting board material). On a BE mounted ski I would adjust and ski to determine the correct NRA. The boot would sit on a platform on the grinding machine which is adjusted to equal the NRA. Then you toss in a cutting board and 2 perfectly carved toe pieces pop out. Since one raises only the toe of the boot, to fit the binding, the new toe piece has to be at the correct angle. Aside from being a tedious process, it works quite well. This allows one to use that ski boot in any binding with the same delta angle. Then a new adjustment like The Skiers Manifesto advises comes along, one changes one thing such as the ankle glide path and you have to make a new toe piece starting the whole process from scratch. This hasn’t been an easy cure in my experience.
Prior to my introduction to the Manifesto I had a hip issue. I solved this by loosening my boots to the point where I would hit the cuff just before I hit maximum ankle flex. When I read this blog, I was stunned at the fact that I wasn’t smart enough to figure out to allow ankle flex years ago. I realized that the whole ramp issue was the culprit; every time I tried to ski or skate in an ‘off the shelf’ configuration I would fall forward on my face due to too much NRA. I had to buckle the boots tight in order to not fall forward out of my boots. With the BE and the ability to override the NRA issue, I can actually ski with as much unimpeded ankle glide path needed and use my ankles as they are designed!! All these adjustments have also allowed me to go from DIN settings of 12-14 and still pre-releasing to a civilized DIN setting of 6 and never pre-releasing.
The bottom line is that David’s methods of boot fitting are the correct way. I went at it backwards by starting with NRA. First set up the optimum position and mobility of the foot within the ski boot. Personally, I would like to start with a ski boot with zero ramp. But that’s not going to happen for a while. So go with David’s recommendation of finding a starting point of ramp as measured using his methods. Then fine tune the NRA per his instructions. In my experience, every time one changes anything in the ski boot the apparent NRA changes (ANR.) With over a decade on the BE and hundreds of boot changes, I have yet to perfectly quantify the correct NRA off slope. I actually tried standing on a piece of plywood in an attempt to find the NRA in-shop. I didn’t ever fit the boot first with all the knowledge that is shared in this blog so I can’t say it doesn’t work. A major boot change occurred recently with no chance until next year to see if it corresponds to what I could feel measuring NRA in the shop.
I have no illusions, part of this is ‘art’ and David’s been ‘painting’ on ski boots for decades so I’m only speaking from my perspective. I definitely see it as a good place to start and am sure that it will get one close which is a positive and better than what anyone else is doing with ski equipment. I say ANRA because with my ski boots at about 10% alignment originally, the BE got me to an APPARENT optimal fore/aft balance dictated by the ski boot but still completely misaligned. I currently find the optimum NRA for bumps and groomers to be different (1-2degrees if I remember correctly), but unfortunately I can’t be positive until tested next season. I see world cup racers struggle in one discipline and winning gold in others. It’s all about Net Ramp!
To me ideal ski equipment set up would be as follows;
- Get the boot set up as perfectly as possible. By following The Skier Manifesto or have David do the work!!
- Have a ‘next generation’ BE which would have infinite (not incremental) adjustment to be able to fine tune the delta to the skier’s comfort. Note; I have that and a number of configurations patented already but am currently trying to figure out how to build an infinitly adjustable prototype that is feasible for my budget.
- Any time a change is made in the boot, the BE can be adjusted if necessary.
- Have unbelievable fun skiing!!
My Closing Comments
Based on my most recent experience, I now believe that the essential starting point is for a skier to learn how to assume a strong ski stance. Only after they have acquired a kineasthetic sense of a strong stance, should they attempt to find the correct ramp angle on a device like a Stance Ramp.
I also think it probable that bump skiing requires a different ramp angle than race/recreational skiing. This remains to be established.