I just love it when people rethink the way things are explained. Skiing, swimming, cooking, anything. Fresh ideas and fresh perspective is always helpful. Thanks Joe
As a PSIA level 3 I can say that he is right and the C turns diagrams are not. USSA does the same thing. They should put him on the thank you list rather than the naughty list. I would suspect that only a few with major ego problems would actually be offended. PSIA is a great organization but it is not perfect and all but very few would argue with that.
I am a Level 3 PSIA and have always found the C shaped turn examples to be wrong since I couldn't do them, unless I was on a slalom ski (no ego here 🤣) You have very logically confirmed what I have always believed, but actually felt many times I was doing something wrong, in medium to long radius turns, with medium radius turns being the worst. Also the flatter terrain example fits for me as well. NICE JOB!
Cool visualization! You're definently 100% right. Although the things we learn and teach about the "C" shaped turn is still all correct. I think we just needed a way or method of visualization to explain everything and thus we came to a very easy visual: C shaped turns. And ofcourse the combination that in lower technical levels such as parallel skiing the turn shape is much closer to a C shape.
Love the thinking and work that goes into all your videos. I think the C-shape is intended as a conceptual tool and, as such, is perfectly fine. That said, comparing a theoretical ideal to reality is also a good learning tool. Love the negative and positive, comparing time. One can also compare pressure, edge angle and rotation. It seems to me that the skier in red has a lighter touch at the top of the turn, less pressure, than the skier in blue. He also seems to spend less time in the ride phase. The negative/positive helps me see this. Joshua Duncan-Smith’s “How to Ski - Dynamic Carving” demonstrates the more C-shaped turn in the wide spectrum. Would love to see that in negative/positive
Very good work. I had similar thougts about that. A perfect C shape is, as you said, quite impossible when you riding at max possible forces on a steep slope. You need to turn harder in the first part of the turn to "make direction", when you are to late to turn, you need to do direction at the worst point with max downforce and max tilt which may lead in a drift, boot out or a high sider.
100% agree, yet, every PSIA exam and clinic reenforces the ideal "C-Shape". I wish "they" would just use "C" as a teaching tool to discuss the fundamentals throughout a turn, but THEY DON'T. During ski exams and clinics, my turn shape was described as a comma, even on blue or steeper pitches. They want to see a perfect C shape ALL THE TIME. Consequently, we all try to, almost, artificially, create that super early turn initiation and edge angle to round out the top and not have that "abrupt" bottom half. "Leapers" anyone? Yet, the edges at the bottom are, as you describe, going against gravity. Sure, it's a worthy goal but it shouldn't be the ideal skiing standard. Hopefully, it'll change because it makes for a stressful skiing/learning experience. Plus, your mention of carving skis is so true. Not everyone (teachers and/or students) is going to be on narrow front side skis that are easier to tip on edge nor should we. Otherwise, the ski school should make carving skis mandatory for lessons. Also, we should mention the length of the skis and their turn radius helping or hurting the overall shape of a small or medium radius turn. Being very tall and usually on wider 180+ skis, it's kind of silly to expect everyone to be on skinny 170's with a 12m turn radius.
PSIA has had a lot discrepancies in movement analysis over the years. This one has been in question for some time !! Great break down !! ( retired instructor with over 27 years teaching )
Good thoughts! The C can be over emphasized. I think it is good when directed at intermediates who transition poorly making their normal Z shaped turns. My bias is simultaneous edge change then whatever is appropriate after that for your intended outcome.
You are 100% correct that the two halves will never be symmetrical because of the effect of gravity. That is true. And this is more the case where gravity plays a bigger part, on steeper terrain. However, I do find that it's helpful for beginner and intermediate students to have a mental model to picture in their heads when learning to ski. Your statement is more accurate. But to get an idea across to a student, I think Big C / little c gets the point across nicely. I do think the point you bring up about pressure to the outside ski at the top of the turn deserves more discussion. When you have lower pressure and lower edge angles, we rely more on rotary skills to initiate the turns. To get your comma shaped turns, we really need to drill that more with our students. And notice that as we progressively increase edge angles, the ability to use rotary decreases. This could also explain the comma shape.
I agree with you we not skiing C shapes really but a parabolas on the flats we ski more symmetric parabola's like you used to see text book of math class, , when you gain speed and incline you need to ski a rotated parabola aka the shape of parabola will look asymmetric, the exit will be longer then the front half of the curve.
I am so pleased you bought this up.....coz it's been bugging me too. Why say C it's not C shaped unless it's a green slope. Once the slope increases and g forces go up even just to 1.1 according to my Carv app, then it is exactly as you say; comma shaped!
Just analyze forces on slope to get path of COM, not of skis. Done this 40 years ago, but 'skiing myths' are so hard to die. Shape of the turn according to Newton is determined by external forces acting on a skier, external forces (edge grip in common ski language) are dependent on edge angle and skidding angle and this is all you have to take into account. Skiing is manipulating those two angels and keeping balance at the same time.
I've never been a fan of the 'C' in turn shape explanation, which appears everywhere. In JD's explanation he refers to a comma with a tighter radius above apex, but it can go the other way as well, depending on input. When the skis are released at transition there is little pressure on the ski other than normal 1G body weight, consequently the skis are relatively flat and edge roll angle begins to develop. Through the fall line into completion pressure builds and the outside ski decambers more and edge angle increases, which tightens the radius through completion, resulting in an upside down comma shape. A good skier will employ different turn shapes based on intent, intensity, impulse, speed, rotary movement, roll angle development and amount of pressure directed to the outside.
Joe, I agree with the gravity effect as you describe. But maybe more relevant is directions of travel (edge engaged skis vs COM). The quickness in initiation maybe redirecting the light skis to change from diverging to converging paths of travel to build force. Thank you.
I like your description of the way gravity acts before during and after the fall line. I will say I don't think anyone is supposed to take the C shape turn literally... I think it's understood to be a whiteboard concept sort of thing. Personally I dislike the C shape concept because it places the "beginning" and "end" of the turn at the ends of the C, where I prefer the apex to apex framework.
Is it my imagination or do the video comparisons show that the transition itself - when the skis are flat to the snow's surface - isn't centered between the fall lines? In fact, the transitions appear much closer to the fall line, as demonstrated with your "negative flash" analysis (which were awesome). That, in itself, is extremely illuminating! But it also means that the difference in timing between the "top half" and "bottom half" of the turn isn't as large as your "flash" comparison indicates ... which would make sense since the physics dictate the top half should take *longer* to traverse than the bottom half due to the additional kinetic energy you develop through to the fall line. Also, isn't it the case that a carved turn can be "shaped" according to the skier's demand, mostly due to edge angle creation/removal but also partially through fore/aft motions? For example, in this overhead shot of Mikaela the bottom of her turns (and those of the racer's next to her) are, if anything, tighter than the top halves: th-cam.com/video/UUEUmcaj4j0/w-d-xo.html In other words, I'm not sure there is necessarily a correlation between the duration of the two halves of a turn and the shape of the turn. Still, the fact the transition is actually after the topological "start" of the turn is a big revelation to me. Thanks!
@@skidadTVI recall he was talking about about something other than turn shape - I’ll see if I can dig out his original paper. On your video, makes perfect sense, GS courses are not set for perfect C’s - it’s all about matching the turn shape to make the fastest line. That in turn depends on the individuals bio mechanics, skill and equipment
Old hat I'm afraid. This 'outside ski', 'inside ski' is old hat. It's equal pressure on both skis, but the inside ski is about half a boot length in front of the other. Sometimes more. Your foot pressure is identical on both feet. The plumes given off as you go around the turn are a give-away as to where pressure is being applied. It depends on the race, but modern racers tend to use a mixture of 'drifting' (as done with cars) and carving. So they take a more straight line towards the gates.
@@skidadTV Yeah. Think about it this way. How would you sink more in mud? Standing on one leg or two? Also, the cut you make in the snow carving on one ski is deeper than if you were making two cuts. The single deeper cut will slow you down.
Dumb to encourage C-shaped turns. In the transition your skis are actually pointed 90 degrees away from the fall line. Which means you are slowing down.
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I just love it when people rethink the way things are explained. Skiing, swimming, cooking, anything. Fresh ideas and fresh perspective is always helpful. Thanks Joe
100% correct. Referring to PSIA as doing something wrong in the video was awesome!
PSIA is gonna put you on the naughty list for this one, Joe.
Just wait a few weeks… 😇
PSIA sucks…just saying.
As a PSIA level 3 I can say that he is right and the C turns diagrams are not. USSA does the same thing. They should put him on the thank you list rather than the naughty list. I would suspect that only a few with major ego problems would actually be offended. PSIA is a great organization but it is not perfect and all but very few would argue with that.
But Joe skis better than anyone on the PSIA nat team.
This makes sense
Very nice! I thought for a long time the physics did not lend itself to a C shaped turn.... nice to see the explanation 👍
Best video ever ..we all need to wake up on snow ❤
You are spot on! So glad I found this channel.
As always, spot on! Thanks again for illustrative explanations.
great visual, thanks for mapping that out.
I am a Level 3 PSIA and have always found the C shaped turn examples to be wrong since I couldn't do them, unless I was on a slalom ski (no ego here 🤣) You have very logically confirmed what I have always believed, but actually felt many times I was doing something wrong, in medium to long radius turns, with medium radius turns being the worst. Also the flatter terrain example fits for me as well. NICE JOB!
This makes so much sense. Bravo.
Cool visualization! You're definently 100% right. Although the things we learn and teach about the "C" shaped turn is still all correct. I think we just needed a way or method of visualization to explain everything and thus we came to a very easy visual: C shaped turns. And ofcourse the combination that in lower technical levels such as parallel skiing the turn shape is much closer to a C shape.
Love the thinking and work that goes into all your videos. I think the C-shape is intended as a conceptual tool and, as such, is perfectly fine. That said, comparing a theoretical ideal to reality is also a good learning tool. Love the negative and positive, comparing time. One can also compare pressure, edge angle and rotation.
It seems to me that the skier in red has a lighter touch at the top of the turn, less pressure, than the skier in blue. He also seems to spend less time in the ride phase. The negative/positive helps me see this.
Joshua Duncan-Smith’s “How to Ski - Dynamic Carving” demonstrates the more C-shaped turn in the wide spectrum. Would love to see that in negative/positive
Lots of great comments. But what too many have missed... it sounds way cooler when that initiation is faster!
Very good work. I had similar thougts about that. A perfect C shape is, as you said, quite impossible when you riding at max possible forces on a steep slope. You need to turn harder in the first part of the turn to "make direction", when you are to late to turn, you need to do direction at the worst point with max downforce and max tilt which may lead in a drift, boot out or a high sider.
100% agree, yet, every PSIA exam and clinic reenforces the ideal "C-Shape". I wish "they" would just use "C" as a teaching tool to discuss the fundamentals throughout a turn, but THEY DON'T. During ski exams and clinics, my turn shape was described as a comma, even on blue or steeper pitches. They want to see a perfect C shape ALL THE TIME. Consequently, we all try to, almost, artificially, create that super early turn initiation and edge angle to round out the top and not have that "abrupt" bottom half. "Leapers" anyone? Yet, the edges at the bottom are, as you describe, going against gravity. Sure, it's a worthy goal but it shouldn't be the ideal skiing standard. Hopefully, it'll change because it makes for a stressful skiing/learning experience.
Plus, your mention of carving skis is so true. Not everyone (teachers and/or students) is going to be on narrow front side skis that are easier to tip on edge nor should we. Otherwise, the ski school should make carving skis mandatory for lessons.
Also, we should mention the length of the skis and their turn radius helping or hurting the overall shape of a small or medium radius turn. Being very tall and usually on wider 180+ skis, it's kind of silly to expect everyone to be on skinny 170's with a 12m turn radius.
Absolutely! Great feeling at the top when you get that wip feeling going into the top of the turn. 👊
Gotta love Tycoon and Birdseye. Great stuff love the video. I’ll be looking for you on the mountain this year
Ya I mean, I can lay clean clean arcs (ex racer/current instructor) and Ive never really seen myself leave C shapes. This video is spot on
PSIA has had a lot discrepancies in movement analysis over the years. This one has been in question for some time !!
Great break down !! ( retired instructor with over 27 years teaching )
Great explanation!
Good thoughts! The C can be over emphasized. I think it is good when directed at intermediates who transition poorly making their normal Z shaped turns. My bias is simultaneous edge change then whatever is appropriate after that for your intended outcome.
I like it.
You are 100% correct that the two halves will never be symmetrical because of the effect of gravity. That is true. And this is more the case where gravity plays a bigger part, on steeper terrain. However, I do find that it's helpful for beginner and intermediate students to have a mental model to picture in their heads when learning to ski. Your statement is more accurate. But to get an idea across to a student, I think Big C / little c gets the point across nicely. I do think the point you bring up about pressure to the outside ski at the top of the turn deserves more discussion. When you have lower pressure and lower edge angles, we rely more on rotary skills to initiate the turns. To get your comma shaped turns, we really need to drill that more with our students. And notice that as we progressively increase edge angles, the ability to use rotary decreases. This could also explain the comma shape.
I agree with you we not skiing C shapes really but a parabolas on the flats we ski more symmetric parabola's like you used to see text book of math class, , when you gain speed and incline you need to ski a rotated parabola aka the shape of parabola will look asymmetric, the exit will be longer then the front half of the curve.
Good stuff Joe
I am so pleased you bought this up.....coz it's been bugging me too. Why say C it's not C shaped unless it's a green slope. Once the slope increases and g forces go up even just to 1.1 according to my Carv app, then it is exactly as you say; comma shaped!
great stuff and great job on the video
Very insightful, and helpful for my visualisation. 👉🧐
1/3 : 2/3 break out of the turn. Yes 🎯
Just analyze forces on slope to get path of COM, not of skis. Done this 40 years ago, but 'skiing myths' are so hard to die. Shape of the turn according to Newton is determined by external forces acting on a skier, external forces (edge grip in common ski language) are dependent on edge angle and skidding angle and this is all you have to take into account. Skiing is manipulating those two angels and keeping balance at the same time.
Great video!
I've never been a fan of the 'C' in turn shape explanation, which appears everywhere. In JD's explanation he refers to a comma with a tighter radius above apex, but it can go the other way as well, depending on input. When the skis are released at transition there is little pressure on the ski other than normal 1G body weight, consequently the skis are relatively flat and edge roll angle begins to develop. Through the fall line into completion pressure builds and the outside ski decambers more and edge angle increases, which tightens the radius through completion, resulting in an upside down comma shape. A good skier will employ different turn shapes based on intent, intensity, impulse, speed, rotary movement, roll angle development and amount of pressure directed to the outside.
Joe, I agree with the gravity effect as you describe. But maybe more relevant is directions of travel (edge engaged skis vs COM). The quickness in initiation maybe redirecting the light skis to change from diverging to converging paths of travel to build force. Thank you.
That’s a large factor as well. The “wall” turn/line exemplifies that point
I like your description of the way gravity acts before during and after the fall line. I will say I don't think anyone is supposed to take the C shape turn literally... I think it's understood to be a whiteboard concept sort of thing. Personally I dislike the C shape concept because it places the "beginning" and "end" of the turn at the ends of the C, where I prefer the apex to apex framework.
Picabo mentioned someone making nice comma shaped turns in the Solden 2024 Race.
She is probably a subscriber 😜
Is it my imagination or do the video comparisons show that the transition itself - when the skis are flat to the snow's surface - isn't centered between the fall lines? In fact, the transitions appear much closer to the fall line, as demonstrated with your "negative flash" analysis (which were awesome).
That, in itself, is extremely illuminating!
But it also means that the difference in timing between the "top half" and "bottom half" of the turn isn't as large as your "flash" comparison indicates ... which would make sense since the physics dictate the top half should take *longer* to traverse than the bottom half due to the additional kinetic energy you develop through to the fall line.
Also, isn't it the case that a carved turn can be "shaped" according to the skier's demand, mostly due to edge angle creation/removal but also partially through fore/aft motions? For example, in this overhead shot of Mikaela the bottom of her turns (and those of the racer's next to her) are, if anything, tighter than the top halves:
th-cam.com/video/UUEUmcaj4j0/w-d-xo.html
In other words, I'm not sure there is necessarily a correlation between the duration of the two halves of a turn and the shape of the turn.
Still, the fact the transition is actually after the topological "start" of the turn is a big revelation to me. Thanks!
Wait! When you look back up the hill you’re not supposed to see a series of linked Zs?
I’m thinking situation variables (5 S’s) are a major factor in determining turn shape
Out of interest where did you find the diagram in the main background? I’m sure it’s by my old coach who sadly passed last year.
All the images came from a google search. Sorry to hear and your coach
@@skidadTVI recall he was talking about about something other than turn shape - I’ll see if I can dig out his original paper. On your video, makes perfect sense, GS courses are not set for perfect C’s - it’s all about matching the turn shape to make the fastest line. That in turn depends on the individuals bio mechanics, skill and equipment
great video! just the audio is only in the left ear for headphone users.
You should be able to make a perfect C shaped turn if it is called for.
The missing link here is not taking advantage of potential kinetic energy.
So to continue this logic.... carving on a vertical face would become an I (am going straight to hell) shaped turn 🤣
correct! it is not symetrical...
Do you remember when the Elan shaped ski was called the "parabolic ski?"
Oh course I was 14 yo
Old hat I'm afraid. This 'outside ski', 'inside ski' is old hat. It's equal pressure on both skis, but the inside ski is about half a boot length in front of the other. Sometimes more. Your foot pressure is identical on both feet. The plumes given off as you go around the turn are a give-away as to where pressure is being applied. It depends on the race, but modern racers tend to use a mixture of 'drifting' (as done with cars) and carving. So they take a more straight line towards the gates.
My CARV data shows considerably more pressure to the outside ski
@@skidadTV Yeah. Think about it this way. How would you sink more in mud? Standing on one leg or two? Also, the cut you make in the snow carving on one ski is deeper than if you were making two cuts. The single deeper cut will slow you down.
Dumb to encourage C-shaped turns. In the transition your skis are actually pointed 90 degrees away from the fall line. Which means you are slowing down.
Looks like a Golden Spiral shape:
en.m.wikipedia.org/wiki/Golden_spiral
My line template is the golden spiral. I came to that conclusion 3 years ago.
@@skidadTV
Golden Turn™ Ski School
PSIA is trying to figure out how to teach but they do not know what to teach.
You just boiled it down perfectly