SKI PRO MATT: SLOPE TESTS, DAY ONE


With the shell work completed, Matt’s modified shells appeared to have adequate width in the forefoot and functional clearance for the joints of his ankle/foot complex as did the modified liner for his left foot. But whether the left boot was better than any of Matt’s previous boots, could only be determined during actual ski maneuvers. The dynamic physical environment of skiing with constantly changing forces that can go as high as 3 Gs for recreational skiers, cannot be duplicated in an indoor setting or even in a gait/balance laboratory. In the initial slope tests, Matt compared his left boot shell fit with the modified liner to his right boot shell fit with the unmodified, stock  liner

If CARV were available, it would have been invaluable to help Matt assess his left and right boots and guide him in developing a sound technique. CARV would have also enabled baseline data to be obtained from Matt’s previous boots that could be compared to data derived from his new boots. But since CARV technology is not available until the end of the year, slope testing had to rely on Matt’s perception.

One question that many ask is “what about custom insoles?” The only way to tell is to test them against a reference standard that is the same for everyone, preferably using a system that acquires real time data on the pressures, forces and ski pitch, yaw and roll. In the initial tests, Matt used a stock insole that had been pressed flat in his left boot and the custom insole, made for his previous boots, in his right boot. Once both boots have been modified and Matt has adapted to them, he can try replacing the flat insoles with the custom insoles. I recommend making changes in one boot at a time so the other boot can be used as a reference. This was the protocol used in testing Matt’s boots.

As part of the process, Matt is undergoing kinaesthetic stance training to learn how to tension the arches in his feet and stabilize his pelvis from the balls of his feet up, from the shoulders down and in the abdominal core. The foundation of a strong stance is what I call the Resistive Shank Angle. I will discuss this in a separate post.


18/11/2015 12:30

PRE FLIGHT CHECK

ME: Please try and capture the initial feelings of your left and right ski boots as soon as you start moving on snow by making slow turns in both directions. Focus on the feeling in the soles of your feet and those in your legs and pelvis. I suggest you either use your phone to record them or take notes as soon as possible. Any initial perceived dffferences may either diminish or increase. So you need to capture them as they happen.

MATT: I will put notes into my phone on each chairlift ride. Looking for feelings in my feet and muscles firing off in my legs, glutes or other. I’ll message you and see what you’re up to at some point.


LIFT OFF

Matt is on the hill sending me reports on his phone.

19/11/2015 09:48

MATT: I’m warmed up and ready to head and line up for the gondola. Looking forward to some skiing!

MATT: First run…. Terrible! Left foot feels way better. Right feels squashed and like a brick.

ME: Try doing some slow turns on flat terrain while focussing on the feel in your feet. Try making turns while keeping pressure on an imaginary  toonie disk under the ball of your outside foot. Steer the turn radius with the toonie disk.

MATT: It’s ridiculous, my left foot I can feel the entire skis and I’m making cleaner turns every single time. My disconnected right foot is being blocked on top where you’ve removed material on the left equivalent. I can feel the ground on my left foot. Right one (foot) is bad.

As good as the left one feels, the right one still interrupts to good turn as I can feel what it’s doing/ not doing. Can you make the right one as correct as the left?

ME: Of course.

MATT: The difference is unexplainable. The footbed is sh*t too. Stops me getting any forefoot loading. No room for the ankle and the forefoot is being crushed by the liner.  I’ll head down sooner than later. Having a tight supported foot is so stupid if you want to feel anything.

I was expecting some good surprises and changes in the left foot but never thought it would be so dramatic.

In my next posts, I will discuss modifications to Matt’s right boot, tweaks made to the left boot and kinaesthetic stance training.

 

22 comments

  1. How far back and how high up do you remove the padding? Do you individualize or have you found that removing the same areas is effective in all or most cases?

    I’m reaching the end of my skiing at a ‘real’ mountain and will soon share my equipment modification experiences.

    1. I am in there process of writing a post on tweaks to Matt’s boots. I will show where the padding was removed to on some photos.

      One thing that has been interesting is that, like myself, once room was made for Matt’s forefoot to fully spread and his foot to lengthen, Matt started to feel interference under this longitudinal arch, even with a flat insole. Even after I trimmed and ground the insole down, Matt started experiencing interference again. In my case, I have had to grind the area of the boot board under my LA hollow. I do not perceive the same interference in my typical street shoes. Why? The loads are much lower than those experienced in skiing.

      As several pressure studies had demonstrated, a good recreational skier can experience 3 Gs (3 x body weight) in high load turns. I think it probable that the intrinsic muscles in the arches of the feet do what muscles do; get stronger and bigger when stressed. The power of eccentric contraction in the triceps surae is limited by the tension in the arches. Guess what happens when the arch is ‘supported’? I will post the results of an Australian study that dramatically show this.

      1. Excellent info. I modified the tongue, ramp angle, forefoot width, etc. One area I am having an issue with is my extreme pronation (ankle moves at least 2 inches from unweighted to the inside). I prefer a flat insole but my feet are so distorted that I’m scared to punch the boot anymore to make enough room. My experience with custom insoles and orthotics are that they do reduce my pronation for a period of time but eventually they bruise under my arches or just in front of the heel (very painful). I am considering making a full length wedge to tilt my whole foot. One thing I do not understand is how much lateral space should be in the cuff, if any? My cuff is oval and has the correct for/aft space but at what point should the cuff engage laterally, maybe before my ankle fully pronates?

      2. Clearance for the foot to pronate is a tough one. In terms of lateral space, 1/8 inch is the minimum to allow for liner thickness. For obvious reasons ($$$$$), boot makers aim for the sweet spot when making moulds for ski boots. The best hope I see for extreme cases is 3D printed ski boots that would have CAD files built on the dynamic envelope of the foot. Two inches certainly sounds extreme. Have you considered exercises like the Short Foot? There are therapists who work with foot strengthening exercises. Since retiring in 2005, I never wear anything on my feet in the home, except socks.I also wear mostly minimal shoes with no more than 4 mm drop (heel raise). My feet have become significantly stronger.

        Stance training is an essential prerequisite to setting boot shaft (cuff) forward lean and side cant. There seems to be a wide spread perception in skiing that skiers will automatically find the optimal stance just by skiing. But that has not been my experience. A very small percentage of skiers who get the right boot setup (usually when they are young) do develop a strong stance because they can. I have just finished a sketch for a Stance Ramp that will assist skiers and racers in acquiring a kinaesthetic sense of the optimal stances. I will post this soon.

        Boot shaft side cant. After setting the boot board ramp angle to 2.7 degrees and a few sessions of stance training, I usually start by setting the boot shaft side cant neutral (same space on each side of the leg) when the skier is standing barefoot in both shells on a flat surface. Next, I have the skier stand in balance on one foot in the shell. The shape of the leg has a big effect, especially a low calf muscle mass. Then, with both boots on and buckled with the liners in I have the skier stand on one foot and balance. Then I check the load on the leg to see if the inner (medial) aspect is loaded. Sometimes I will trim one or both sides of the shaft down. There is a reason most elite skiers and racers have thin legs. The real test is of correct side cant skiing. The skier must move into position over their new outside ski and be able to load the head of the first metatarsal without the shaft levering the ski on edge. The tell tale sign this is happening is that the skier will move away from the outside ski to find stability on the inside which acts like a security blanket. Many racers make this security blanket move (actually a retreat) even at the WC level. When a boot has been wrong for any length of time, it trains the skier to use the inside foot and ski. They have no other choice.

        From what you describe, it may be difficult to arrive at a neutral shaft cant.

      3. I worked on improving my feet over the summer, with some improvement noted. A therapists is a good idea. Is the goal to be able to fully load the head of the first metatarsal without loading the ankle bone or using the lateral cuff of the boot? When is the lateral cuff used or needed? I am concerned I have too much lateral space in the cuff.

        Thanks again,

        Mike

      4. “Is the goal to be able to fully load the head of the first metatarsal without loading the ankle bone or using the lateral cuff of the boot?”
        Yes

        “When is the lateral cuff used or needed? I am concerned I have too much lateral space in the cuff.”
        By lateral cuff, I assume you mean the inner aspect of the cuff? Correct? If so, in my model of the ski technique employed by the world’s best skiers, the cuff of shaft of the boot acts as an alignment and reference device to assist in the alignment of GRF from the snow and the force applied to the snow by the skier. One test is to see how easily you can move to one foot and balance on it with your ski boots on. If you feel the cuff digging into one side of your leg, the cant is probably wrong. The cant has to work for both bipedal and monopedal stances. But you should be able to easily and quickly move on to one foot and balance on it.

        The classic definition of balance is the alignment of equal and opposite forces in the same plane(s). In skiing, the dynamic forces introduce centrifugal force which is not really a force. But since it affects the influence of gravity, a resultant force is required. What no one in skiing seems to talk about is the fact that for balance to occur, the resultant force must be aligned with the force applied by the skier in opposition to GRF from the snow. In this paradigm, it is incorrect to show balance across the edges of a ski occurring by the alignment of R and GRF because R is not a physical force. Claiming this shows balance is nothing more than an amateur parlour trick.

        When someone is having problems skiing, a kinaesthetic assessment can often identify issues like pelvic alignment issues or’toed out’ feet which is really externally rotated legs. When one or both legs are externally rotated more that a few degrees, the resulting muscle imbalance of the external/internal rotators can have significant implications for pelvic stability. Over the past few decades, the body work I have had done combined with foot strengthening exercises has had a very noticeable affect on my ability to move with precision on skis.

      5. I am not impeded by the cuff when standing on one foot or switching feet. The fore/aft settings work well, I know exactly where I am in the boot. I have the fore/aft space and reference shank angles working correctly but am still unsure about how much space on either side of the leg is required. How is the inner aspect of the cuff set and used as an alignment and reference? Is foam needed to be added or removed from the cuff to accommodate different leg diameters? Any chance of pictures of Matt in his boots showing the space around the cuff? Looking forward to the stance training posts.

        Thanks again,

        Mike

      6. There should not be visible space between the flesh of the leg and the padding of the liner within the boot shaft. If Matt or most elite skiers or racers were to stand in the shells with no liners there would be considerable space between the calf muscle mass of their legs and the the sides of the shaft. But this is not the case with those with a large calf muscle mass, especially when it is lower on the leg. I have seen several cases recently with females where the shaft impinged on the muscle mass without a liner in the shell. This prevents the foot from sitting properly on the base of the boot. Unless you can get your hands on race stock boots, it is hard to find a performance boot with a shaft that is low enough. Even if you do, it may still be necessary to cut the sides of the shaft down and remove the plastic stiffener around the top of the liner. Once space is created for the calf muscle, the improvement in skiing performance is usually immediate and dramatic. I will post some photos on this issue soon.

      7. Thanks Dave,

        I had about 1/2 inch space on each side of my calf, so I increased the forward lean to 17 degrees and put my powerstrap between the liner and shell. The result is the same buckle setting, same shank angle and almost no space on each side of my calf. This did decrease the range of fore/aft from 14 to around 10 degrees. I did only one foot today and it did seem more stable after I fully loaded my foot. I will try both boots tomorrow, I may still have to add some material to the liner on each side to fully remove any slop.

        Mike

      8. I sounds like you have a thin leg in a boot with a generous shaft. is this correct? Runners and especially cyclists tend to have very thin legs. I use a competition boot. So the cuff padding is in contact with the flesh. But it is not squeezing or constricting. When I am skiing even hard and fast I have no sensation of anything on my leg.

        If your leg is thin, you may be able to introduce extra foam in the upper part of the liner that embraces the side of your leg. It involves either cutting a slit in the outer skin of the liner or opening the stitches, inserting the pads and resewing them. 14 degrees of fore/aft play is a lot. 10 degrees is usually enough. The key is for the power strap to arrest forward movement of the shank so it keeps the centre of force at the top.

        As you are finding out, the key is to experiment in a structured manner so you can assess each change and especially the ability to reverse them if in doubt.

      9. You are correct, my leg is thin and the Atomic Hawx 2.0 130 have a very generous shaft. I could tighten the cuff but that would wreck the oval shape. I am going to experiment with some foam duck taped to the liner, if it work well I will try ordering some stick on high density foam designed to go on the outside of liners. One of the attractions of the boot is it is very heat mold-able using an oven or boiling water, unfortunately you have to pad the pressure points and endure signification pain to get the plastic to move. I would prefer a competition boot if I had access to an experience shop to do the numerous punches I would need. I wish there was an affordable punch for the DIY market.

      10. Recreational boots tend to be generous in the cuff. World Cup boot techs use what looks like a big C clamp with a mount for a cage on one end and a punch head on the other as opposed to the wall mounted press. I usually got the best results with one-shot overnight punches. I will try and get some photos of the C-clamp presses and post them and find out who, if anyone, makes them. I may try and modify a wood working clamp. Right now I have access to a boot press.

        You are playing it smart by not over tightening the cuff. It is not that big a deal to open the stitches in the liner on the sides of the instep. You can insert pads on either side. When it feels right skiing with the pads in place, you can get a shoe maker to sew the liner back together. An easier way is to stick foam pads on the outside and duct tape over top. You would have to replace it from time to time. But it would probably do the job.

        There is a really good reason why I always get the stiffest race shell I can that I will explain in a post soon.

      11. I am probably going to start over with an all polyether shell since the heat molding of the boot is still not ideal and I ended up having to punch and grind anyway. The Head Raptors and the blue Lange RS series would work but would need a lot of punches. Lange has the boot in 97mm or 100mm lasts. Both are available in 130/140 flex any disadvantage to the Langes vs the Heads?

        I have found a couple skate boot punches that should work for ski boots: https://blackstonesport.com/en/product/boot-punch-press http://blademaster.com/web/en/skate-service-tools/421-sc6000.html

        My wife has a narrow, low volume true 21 foot. She is currently in a Lange 21 junior short cuff boot. It is a 22 shell with a plug in the toe and 97mm wide. Heel is way too big. One shop tried to heat and compress the heel, didn’t do much.

        Doesn’t appear to be anything on the market that small except very soft kids boots. The Head B5 at 95mm is still too wide and long. Lange has a true 21 Short Cuff shell coming out this year but it is a 97mm last. I have found a 92mm World Cup Lange boot in a 22 shell which may work if I swap cuffs from her old boots and punch the toes, though it is still too long but at least the heel would fit. Any ideas?

        Mike

      12. Hi Mike, I apologise for the delay in responding.

        “Both are available in 130/140 flex any disadvantage to the Langes vs the Heads?”
        When I worked with racers back in the ’70s and ’80s, I mostly worked with Langes. Today, I prefer Head and Atomic. There are probably other boots that are as good. But it is a matter of familiarity. Every boot requires a new learning curve. I will be posting soon on my experiences with Ski Pro Matt. Matt is very athletic and fit. But he is 6’2″, 225 lbs with a US size 10 men’s foot. His problem is that his foot is big boned and way outside the spec of most racer’s feet. He started on a Head 130 flex boot. It required a lot of shell expansion and radical liner surgery. It quickly became obvious to Matt that the plastic was far too soft and was distorting under load (I will post on this in the future). He ended up switching to a very stiff Atomic boot that required the same extensive expansion. A big problem was that the liner/tongue structure would not allow Matt’s shank to move forward in the shaft so as to come into contact with the front of the shaft. In the past few days, we have finally gotten the functional room in the boot that Matt needs. This, after a prolonged and aggressive effort. Based on this experience, I think the odds of someone with a foot and leg like Matt’s has a better chance of winning a lottery than getting a boot they can ski in.

        “Doesn’t appear to be anything on the market that small except very soft kids boots. The Head B5 at 95mm is still too wide and long. Lange has a true 21 Short Cuff shell coming out this year but it is a 97mm last. I have found a 92mm World Cup Lange boot in a 22 shell which may work if I swap cuffs from her old boots and punch the toes, though it is still too long but at least the heel would fit. Any ideas?”

        When I worked with Lange, I got great support from Lange USA’s racing division. I knew how to read the shell codes. So I knew Lange made a size 4 shell even though the distributor told me otherwise. The smallest cuff fit 4-5-6. If need be, I used to cut the height of the cuff down so it would sit lower on the shell bottom.

        To adjust excess heel width, I used to cemement a band of very dense foam around the heel pocket of the shell and then grind it to shape with a Foredom grinder. You can also insert padding in the liner although it is less precise. Excess length is not a big deal if you pad the instep of the tongue to obtain firm (but not excessive)(pressure on the instep. I slit open the stitches on the little toe side and slip in dense foam pads of a few mm thick until I get the desired pressure. When it is right, a a shoemaker can sew the tongue back together.

        Good luck.

      13. Hi Dave,

        Thanks for replying. Tried a Lange WC 92mm boot in a 22 for my wife –
        compared to her current Lange 97mm width boot in a 21 (22 shell with
        short liner and a plug in the toe) only the forefoot is narrower, heel
        is almost identical. Overall volume is a little lower in the WC boot
        but not enough. You are correct about finding the small sizes, it seems
        to be a well kept secret, but I have found a true 21 shell from Lange.
        Her current 21 (22 shell) is 266 BSL, the new true 21 shell is 260 BSL.
        I believe that normally a change is shell size is about 10mm, I am
        suspicious that Lange has maybe only shortened the toe and not changed
        the mold of the rest of the boot since the drop in length is only 6mm
        not 10mm. Not sure the true 21 shell will make much difference and it
        also creates some ski compatibility issues due to most track systems
        only go to 263mm.

        Her current boots are better since I have added an addition 9mm high
        density foam on the boot board to take up the volume and added some
        nickleplast foam around the heel of the shell like you suggested. Did
        you use contact cement to hold the heel foam to the shell?

        Looking forward to your posts on the Atomic boot. Head has some stiffer
        boots in the B series, as does lange in the Z series, but both are
        narrower than the Head RS. Were there any issues punching them due to
        the mix of different plastic in the Atomic boots?

        Great info, thanks again,

        Mike

      14. Hi Mike,

        “I am suspicious that Lange has maybe only shortened the toe and not changed the mold of the rest of the boot since the drop in length is only 6mm”.

        The cost of the molds used to inject shells is huge. So boot makers use a number of options to minimize the number of molds. Back in the ’70s they came out with a concept called Mondo Point which replaced 10 or 11 full shoe sizes with about 8 or 9 Mondo Point sizes. Fortunately, it didn’t fly with consumers. The other thing book makers do is use shorter liners in shells to give half sizes. Then of course race models are much narrower than the same size foot to give more ‘precise control’. How about, ‘to make the foot more dysfunctional’?

        “Her current boots are better since I have added an addition 9mm high density foam on the boot board to take up the volume…. ”

        I like to use gasket cork for this because it doesn’t compress or even sheet aluminum cut to size and glued to the boot board.

        “…. and added some nickleplast foam around the heel of the shell like you suggested. Did
        you use contact cement to hold the heel foam to the shell?”

        I sand the plastic around the heel of the shell then use a cement like Shoe Goo that doesn’t need really on firm pressure to make it stick.

        “Were there any issues punching them due to the mix of different plastic in the Atomic boots?”

        Were there any issues?? I could write a few volumes on the process. You will not believe what had to be done to the Atomic boots to create a functional environment for Matt’s feet. I will post on this soon.

      15. Hi Dave,

        Not sure if I should have posted this somewhere. I’m working on a Rossi(re-branded Lange) Race boot to replace my Atomic Hawx due to the cuff issues we discussed and difficulty punching the Atomic multiple plastics. The race boot is needing a lot of punches, but at least it is all polyether plastic, so I built a tool using these instructions – http://www.epicski.com/t/90523/ski-boot-punch-instructions

        I am setting the ramp angle to 2.6 degrees – which works well for me in my Hawx. Rossi has some race documentation showing the ramp angle on some of their race boots between 3.5 and 4 degrees and 2.5 to 2.6 degrees on their World Cup boots – same as you found!

        I’ve included a link to a video about a bootfitter in Switzerland with a few different ideas. https://www.youtube.com/watch?v=Au1Wc-yw5Vo

        Points I noticed: 1. Sets forward lean where knees don’t pass toes=>instead of the maximum available ankle flex

        2. Added eva foam to zeppa then adjusted ramp angle=>this would keep the zeppa thicker and stronger and ensure a good match with the interior of the boot, not sure if I would have enough vertical space in my boots though.

        3. Screwed zeppa down to secure in boot => seems like a good idea

        4. Created footbed that rocks at heel, similar to what Superfeet sells for skates – seems to create pressure on the ball of the foot when tilting the ankle, maybe less stress on the feet trying to pressure the ball of the foot but I’m suspicious of anything under the arch, maybe tilting the ankle is the only way to get pressure on the ball of the foot with this footbed.

        Looking forward to you’re thoughts.

        Thanks again,

        Mike Murray

      16. Hi Mike,
        I am just getting back to my blog. So I will give you a few quick thoughts for now.

        I am setting the ramp angle to 2.6 degrees – which works well for me in my Hawx. Rossi has some race documentation showing the ramp angle on some of their race boots between 3.5 and 4 degrees and 2.5 to 2.6 degrees on their World Cup boots – same as you found!
        > I am seeing signs that bad ski technique in WC has bottomed out and is moving in the right direction (finally). I suspect a lot has to do with racers getting total ramp angle in the right range. Although 2.6 seems to be the magic number, I have found that 2.4 zeppa plus 0.2 delta (binding ramp) makes it easier to load the shovel of a ski.

        I’ve included a link to a video about a bootfitter in Switzerland with a few different ideas. https://www.youtube.com/watch?v=Au1Wc-yw5Vo

        Points I noticed: 1. Sets forward lean where knees don’t pass toes=>instead of the maximum available ankle flex.
        >
        > This is generally where the static preload shank angle ends up. But arbitrarily setting forward lean may not enable the SR.

        2. Added eva foam to zeppa then adjusted ramp angle=>this would keep the zeppa thicker and stronger and ensure a good match with the interior of the boot, not sure if I would have enough vertical space in my boots though.
        > I prefer to use gasket cork for this although EVA foam should work if it is dense enough.

        3. Screwed zeppa down to secure in boot => seems like a good idea
        > The best option I know of so far is to have a machine shop design a titanal or high grade aluminum top plate that sits on top of the zeppa and is secured with screws through the base and zeppa. This work should be done by a machine shop using a CNC machine. I have had good results using Ikea screws for particle board. This only works if the zeppa is hard, dense foam that will accept screws. I will post on this at some point.

        4. Created footbed that rocks at heel, similar to what Superfeet sells for skates – seems to create pressure on the ball of the foot when tilting the ankle, maybe less stress on the feet trying to pressure the ball of the foot but I’m suspicious of anything under the arch, maybe tilting the ankle is the only way to get pressure on the ball of the foot with this footbed.
        > Sounds like a bad idea. Do you have a link where I can see what Superfeet is selling for skates?

        More later.

      17. Thanks Dave,

        Here is the link for Superfeet Yellow for skates – https://www.superfeet.com/en-ca/insoles-and-sandals/yellow

        They have a couple other models, the Black has almost no heel lift and the Carbon is stiffer.

        The heel rocks on the rounded plastic bottom, the pegs limit how far it will roll in each direction. They seem to allow tipping side to side faster due to the rounded bottom. I can feel where the plastic ends just past the arch, definitely a no go for me.

        Mike Murray

      18. Having modified hockey skates for a study that was presented in 2012 at a sports science seminar in Barcelona, Spain and as the lead inventor of a footwear technology that may see production in a cycling shoe, the Superfeet concept doesn’t make sense to me.

  2. Interesting…I recently modified my liners along the same lines. I cut a hole in the liner by the medial ankle and body of the talus, and took out part of the liner on the lateral metatarsal area to let my forefoot flatten when I came forward. I have reasonable arches, and the insole of the stock liner had a small medial arch support which didn’t seem to be restricting my medial foot compression…but I flattened it a bit anyway. The result is that my foot behaves now much more like a foot, but I have to think about what it’s doing in my turns. If the foot and ankle are immobilised, as happens in most boots, all you’re thinking about is what you’re doing with your knees and hips to get onto and off your edge. With a freer foot and ankle, I get a lot more response from my ski in the turns, but I have to be a lot more conscious of what I’m doing. To ski the other way, with my foot immobilised, I feel more stable but less effective.

    1. The cue I like to use is to imagine a small disk of pressure under the ball of the outside foot about 3 cm in diameter. I relate this to a toonie or looney which are two and one dollar Canadian coins. As you move to the uphill or inside ski while it is still on its uphill edge, try and find the pressure disk under the ball of what will become the new outside foot of the turn. Keep the pressure disk under the ball of the foot and steer it in the direction you want to go. Establishing the pressure disk and maintaining it through the turn, takes care of stance and alignment issues especially of you combine it with the internal rotation outside leg/external rotation of the inside leg reversal that should occur as you cross the fall line and enter the bottom of the turn.

      I would check the ramp angle and shape of the Lange boot board. It is probably much steeper than 2.7 degrees that seems to work best for most good skiers.

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