Individual Review CARV

[Seldomski]

Ted Ligety Performance Camp | Deer Valley Resort | Park City, Utah

www.deervalley.com

Participants will be outfitted with their own CARV in-boot unit to provide real-time feedback throughout the weekend; individual video analysis will be provided as well. Each morning will include private access to a freshly groomed, private run, culminating with a First Tracks experience on Sunday, January 8.

$4500 is a bit much for me, but should be fun.

 

[RSTuthill]

Only if you've decided a priori that the centre of gravity needs to be forward of behind the ankle. Haven't you already described the alternative with dorsiflexion?

Well, I just don't think that WC racers ski that far into the back seat is all. I could be wrong. (It has happened before.) And I will have to track down those references to see how they drew that conclusion. I have not yet done that.

Oh, and btw, Mike also said something about the medial/lateral loading of the boot cuff being larger than the anterior/posterior loading. I think we can say on inspection that is incorrect. With all due respect, Mike. The ski under foot is only 6.5 to 11.0 cm wide and offers almost no resistance to being rolled on its side via knee movement. The ski lengthwise, by contrast, offers huge resistance by comparison because it is so much longer than its width. In addition, there is the ankle joint that facilitates anterior/posterior loading.

 

[Mike King]

Well, I just don't think that WC racers ski that far into the back seat is all. I could be wrong. (It has happened before.) And I will have to track down those references to see how they drew that conclusion. I have not yet done that.

Oh, and btw, Mike also said something about the medial/lateral loading of the boot cuff being larger than the anterior/posterior loading. I think we can say on inspection that is incorrect. With all due respect, Mike. The ski under foot is only 6.5 to 11.0 cm wide and offers almost no resistance to being rolled on its side via knee movement. The ski lengthwise, by contrast, offers huge resistance by comparison because it is so much longer than its width. In addition, there is the ankle joint that facilitates anterior/posterior loading.

Except that WC athletes when carving a turn do not pressure the cuff of the boot anterior/posterior cuff of the boot, they pressure the lateral/medial cuff of the boot. Two pieces of data to support this: 1) the results of the birdcage experiments, and 2) coaching by a top 30 World Championship SG athlete.

 

[Mike King]

Aliprandini might disagree.

And Mr. Gellie himself has plenty of videos I think you'd describe as showing high ski performance where he's doing exactly that.

@RSTuthill Wörndle et al. is just an Austrian coaching manual, haven't read it but every now and again Austria comes up with some arbitrary idea of how good skiing should be defined and how it should be foisted on tourists.

Not sure who Aliprandini is, how he would disagree; might you elucidate? Otherwise, I think we are in agreement.

 

[Mike King]

Wow, I step away for a couple days and all sorts of postings appear. I probably should not be commenting before doing all the due diligence I said I would do, but what the heck? At some point I am just gonna send Prof. Scheiber an email with a list of questions on the Nakazato et al paper, but off the top of my head these are some interim comments on the overall topic.

First of all, I am unsure what is meant by vGFR in Nakazato. Aerospace papers, in the ASME for instance, pay rigorous attention to nomenclature definition. I guess in bio-mechanics, not so much? I assume what is meant is the total force in the sagittal plane perpendicular to the ski base? Is that a good assumption? Otherwise I do not know why this paper would be germane.

Second of all, Figure 5 of the paper makes the point I was trying to make. Shin loading of the boot cuff is very important. Almost all of the differences between the pressure insole measurements and the force plate measurements are almost surely due to shin loading of the boot cuff. What the authors call shank forces. This caught me off guard when I first read it because the boot shank is in the sole of the boot in American usage. In this usage they are talking about the shank bone, or the shin, however.

Third, the authors allege that the center of gravity of very high level skiers is almost always above a point on the ski behind the ankle. To which I would reply "which ski and in what portion of the turn"? Remember there is the issue of sagittal ski split during the highest loading phase of the turn so to begin with this statement is not well defined. Secondly, if we are talking about the outside ski only, then I would submit that would be a priori evidence that the skier was in the back seat. And this sounds very much as if the conclusion was derived from pressure insole data. But what I found most curious is that the authors had taken force plate data that should have resolved the issue. There were two force plates on each ski, one under the toe and one under the heel. And yet they chose not to publish them.

Fourth, I would note that there are two ways of pressuring the cuff of the boot. With the balls of the feet unweighted via dorsiflexion of the foot and without such unweighting. It makes a big difference in the distribution of load on the ski. Thus the force plate method is required.

Fifth, in the interest of full disclosure I pretty much carve all the time. Laying trench as it is called, which may be an eastern expression, I dunno. Depending on the ski in use, I can also make the tips or tails of the skis skid out, usually at the bottom of the turn. But I am always eager to learn which is why I am posting here. I think that what bothers me is the idea of a system that tells you to ski in a certain prescribed manner. For instance, in Nakazato, the data show a typical stand on the outer ski technique. But if you want to be quicker to the next edge, you have to engage the inner half much earlier in the turn, perhaps starting to load the inside ski as soon as the fall line is crossed. In my opinion there are many ways to ski successfully, and I am somewhat skeptical of a system that would push the skier in one direction of another. I would like to see the data and make my own decisions unencumbered by skiing IQ scores and coaching recommendations. So I am going to continue to explore the CARV capabilities.

The physics of a ski are such that if you are pressuring the tip, the tail will be displaced from the path of the tip. That is not pure carving. So, if you are pressuring the front of the boot, the result will be a displacement of the tail of the ski.

 

[RSTuthill]

Except that WC athletes when carving a turn do not pressure the cuff of the boot anterior/posterior cuff of the boot, they pressure the lateral/medial cuff of the boot. Two pieces of data to support this: 1) the results of the birdcage experiments, and 2) coaching by a top 30 World Championship SG athlete.

Please elaborate with a citation or url re the birdcage results and the coach particulars. And please explain how the skier loads a boot cuff in the medial/lateral direction other than by skiing hard (which doesn't qualify as an intentional act since it is not a degree of freedom available to the skier.).

 

[RSTuthill]

The physics of a ski are such that if you are pressuring the tip, the tail will be displaced from the path of the tip. That is not pure carving. So, if you are pressuring the front of the boot, the result will be a displacement of the tail of the ski.

Not quite correct. See my remarks on how it is done. The important thing is the proportion of the load on the ski imparted thru the toe and proportion imparted thru the heel. And the paper cited earlier demonstrates that. The PI's failed to measure 50 percent of the load.

Btw, I suggest we confine the discussion to free skiing recreational speeds. No higher than GS. Not that the principles are much different, but I don't know if a lot of measurements taken at those speeds where the equipment is quite different. Less reactive boots and very large radius skis with different stiffness distributions.

 

[Zirbl]

And please explain how the skier loads a boot cuff in the medial/lateral direction other than by skiing hard

What do you mean by "skiing hard"?

 

[Zirbl]

Not sure who Aliprandini is, how he would disagree; might you elucidate?

Just picked an example of a racer with a particular penchant for drifting in and carving out. Fair to say it's pretty high-end ski performance.

 

[RSTuthill]

What do you mean by "skiing hard"?

Fast enough so that imperfections in the snow surface will cause edge angle changes in the absence of reaction force from the boot which ultimately originates from the shin on the cuff and the footbed thru the zeppa and boot sole.

 

[Zirbl]

Are you saying that when you incline, there is no medial and lateral pressure from the legs against the cuffs, or have I misunderstood you?

 

[PisteOff]

I’d like to report a hijacking……..

 

[Lorenzzo]

I’d like to report a hijacking……..

My ignore list grew off this thread.

 

[Wade]

Btw, I suggest we confine the discussion to free skiing recreational speeds. No higher than GS. Not that the principles are much different, but I don't know if a lot of measurements taken at those speeds where the equipment is quite different. Less reactive boots and very large radius skis with different stiffness distributions.

I suggest we confine the discussion to skiing with Carv and people discussing their experience with it rather than a dense discussion of the physics and engineering behind it. Maybe start another thread for that?

There were a few people commenting earlier in this thread about not wanting to use Carv because they just want to experience the joy of skiing without being encumbered with electronics. I think that's a reasonable and understandable position to take. If they really want to feel what it's like to have the joy sucked out of something before making a decision though, they could always read the last three pages of this thread.

 

[RSTuthill]

I suggest we confine the discussion to skiing with Carv and people discussing their experience with it rather than a dense discussion of the physics and engineering behind it. Maybe start another thread for that?

There were a few people commenting earlier in this thread about not wanting to use Carv because they just want to experience the joy of skiing without being encumbered with electronics. I think that's a reasonable and understandable position to take. If they really want to feel what it's like to have the joy sucked out of something before making a decision though, they could always read the last three pages of this thread.

Sorry, but this discussion is germane. I questioned whether or not a system that fails to measure a significant part of the loading of the ski can offer reasonable coaching. What was offered in rebuttal was a technical paper that actually confirmed my point. Carv fails to measure almost half the forces. Thus we are discussing the foundational validity of the technical approach of the system. Sorry if you find it boring or beside the point.

 

[PisteOff]

Look, it’s obvious to everyone what the limitations of CARV are. It’s $200 for chrissake!! People obviously don’t put any value on their time having spent what equals thousands of dollars worth of time on the discussion. I would’ve bought you one just to not have received all the notifications for these posts……..

Freud had a diagnosis for this…….

 

[geepers]

Sorry, but this discussion is germane. I questioned whether or not a system that fails to measure a significant part of the loading of the ski can offer reasonable coaching. What was offered in rebuttal was a technical paper that actually confirmed my point. Carv fails to measure almost half the forces. Thus we are discussing the foundational validity of the technical approach of the system. Sorry if you find it boring or beside the point.

Kind of depends how you ski. Plenty of folk such as Richie Berger, Gellie, Robertson, every single one of the CSIA L4s I've ever worked with) advocate skiing primarily through the soles of the feet. Contact of the shins with the front of the boot as a reference yes, but not as a pressure point. The feet after all are stacked with nerves/sensors much more so than the shins.

May also be a good idea to listen to this Arc City discussion between Jimmy Krupka and Sam DuPratt who are/have both been on the USA ski team. The relevant part starts at about 23:45 where one of 'em says "...flexing your boots".

The TL;DR is:
1. On the WC they don't stay forward the whole time, contrary to what these two were advised growing up
2. Staying forward on the front of the boot is slow
3. The key is to work the ski from tip to tail through the arc


Lastly, CARV have a 100 day return if you are unhappy policy and are promoting it heavily atm on FB. Would be a good idea to read the fine print (like rtn in original packaging) but what have you got to lose (besides entrenched beliefs)?

 

[Wade]

Sorry, but this discussion is germane. I questioned whether or not a system that fails to measure a significant part of the loading of the ski can offer reasonable coaching. What was offered in rebuttal was a technical paper that actually confirmed my point. Carv fails to measure almost half the forces. Thus we are discussing the foundational validity of the technical approach of the system. Sorry if you find it boring or beside the point.

Thanks! I do find it boring and beside the point. Apology accepted!

And I’ll accept that this branch of the discussion was germane at one point, but ceased to be so when you went down a route of dissecting a research paper that has only a tangential relationship to the product rather than discussing the product itself.

Nobody cares whether you buy Carv or not. If you’re really interested in buying it, as @geepers and @PisteOff pointed out, it comes with a guarantee so if it’s not for you, just return it and you’re out nothing.

But you lead off your entry into the thread by saying you couldn’t be bothered to read the 17 pages of user experiences, reviews and technical discussion that had been contributed over the last few years, so I suspect you really have no interest in buying Carv.

It was pretty well established in those 17 pages that Carv doesn’t measure cuff pressure and requires users to ski through the soles of their feet to achieve good scores, and their coaching videos and tips reinforce that approach. If you’re not on board with that approach, Carv probably isn’t for you.

 

[RSTuthill]

Thanks! I do find it boring and beside the point. Apology accepted!

And I’ll accept that this branch of the discussion was germane at one point, but ceased to be so when you went down a route of dissecting a research paper that has only a tangential relationship to the product rather than discussing the product itself.

Nobody cares whether you buy Carv or not. If you’re really interested in buying it, as @geepers and @PisteOff pointed out, it comes with a guarantee so if it’s not for you, just return it and you’re out nothing.

But you lead off your entry into the thread by saying you couldn’t be bothered to read the 17 pages of user experiences, reviews and technical discussion that had been contributed over the last few years, so I suspect you really have no interest in buying Carv.

It was pretty well established in those 17 pages that Carv doesn’t measure cuff pressure and requires users to ski through the soles of their feet to achieve good scores, and their coaching videos and tips reinforce that approach. If you’re not on board with that approach, Carv probably isn’t for you.

Well thanks. Sorry you weren't around to give us the executive summary earlier. But the responses that I got did not indicate a consensus on those points. Rather the paper was put forward as a justification of the CARV approach. It should also be noted, however, that the paper says that pressure insoles are missing half the relevant loading forces. If you consider that irrelevant, well, you are entitled to your opinion.

I assume that the level of snark in your reply indicates some sort of connection with the product, it use, or its methodology. So, thanks for your input, and have a great winter.

 

[PisteOff]

I assume that the level of snark in your reply indicates some sort of connection with the product, it use, or its methodology. So, thanks for your input, and have a great winter.

Yes, a connection with the product, its use and the subsequent results. It doesn’t have to be perfect to achieve its objective. Much like the golf swing (God forgive me for bringing up the golf swing) the individual mechanics of skiing are personal and subjective. Think Jim Furyk for a glaring example. A pure swing like a pure turn has its physics with all its appropriate laws. How we as individuals strive for that pure turn/swing vary based on a multitude of factors.

Does CARV work for everyone? No. I’ve not seen any instruction and/or training aid in sport yet satisfy that lofty goal.

It was pretty well established in those 17 pages that Carv doesn’t measure cuff pressure and requires users to ski through the soles of their feet to achieve good scores, and their coaching videos and tips reinforce that approach. If you’re not on board with that approach, Carv probably isn’t for you.

This is an approach ^^^^ that I personally found very enlightening. Having “get into the front of the boot” being the mantra in the early years only took my skiing so far. It got me out of the backseat, but that’s about all it accomplished. It has a multitude of negative effects in many situations especially if it comes at the cost of fore/aft balance. There are times and places to drive the boot.

I got in on CARV as a founding member during their kickstarter days several years ago. The concept made sense to me. My career is very saturated with engineering, mechanics, power transmission, etc. Like RSTuthill I was skeptical. At the same time I was also intrigued. The skiing lessons I’d taken up to that point had little to no benefit for me. I was accomplishing more on my own through experimentation. I knew my progress was coming through repetition providing me with better fore/aft balance. This is why CARV intrigued me.

I’ve only ever had two instructors impart anything of lasting value. @ChunderBlunder will agree with this as we did this together for years and still do and we’ve obviously discussed it. One was with the international man of mystery @jimmy at Alta several years ago regarding turn initiation and turn shapes. The other was last year at Taos with local living legend Alain Veith regarding COM placement in steep bumps and a simple easily repeated move to get there regardless of line choice. It was forward, but it wasn’t crushing the boot. Not even close.

Getting back on topic……. CARV helped me attain a level of consciousness regarding how to properly pressure a ski through my feet and where in the turn those differing pressures should reside for best results. Learning to pressure my skis in this fashion took my fore/aft balance to another level. I know @KingGrump Is a Jedi master of skiing through the soles of his feet. He can unbuckle his boots (he is often found skiing in this fashion) and ski better than most. While I personally don’t advocate his behavior, I certainly respect his ability. While many of us like to poke fun at him and play devils advocate we all know that his approach to skiing is both very controlled and very fluid. Little energy with maximum result. This is ultimately my goal. You will never see it so well displayed in such gnarly terrain as you will at Taos. Their approach to skiing steep bumped terrain is impressive. The instructors, locals, and regulars are easy to spot. I’ve a number of hours of video of advanced instruction there and never once were the words “pressure the cuff” or “get into the front of your boot” ever used that I can recall. I’m not talking about carving now so I digress.

Let me close with this….. @RSTuthill if you don’t believe in it then by all means don’t buy it but don’t spend hours of your time here trying to tell people who have benefited from it that it is junk science. Our experience speaks louder than your conjecture. You’ve hijacked a thread you didn’t want to read to subsequently spend more time than reading it took to attempt to discredit not only the product, but through association, all that myself and others have experienced. Read the room. This is a REVIEW thread. Feel free to lend your experience once you’ve used the product. Feel free to ask questions of the reviewers who have “experience” with the product. A review thread is not a platform to postulate unless you have in fact reviewed the item in question. Please feel free to start your own thread and beat that engineering horse to death. This is not the place for that discussion. IMHO.