Question for the Ortho experts

[dan ross]

It’s more of a biomechanics issue and everybody’s are developed to varying degrees but the kinetic chain of your joints working in unison are universal. So many factors are at play regarding edge angle it is a dynamic situation -speed , slope angle , strength , skill and equipment all come into play. Ted Ligity has the same joints and muscles as all of us - just better, much better.

 

[Jilly]

How are you rollerblade turns?

 

[Sherman89]

It’s not much before the tibia inclines. I’d guess 5-10 deg. Probably the lower end.

ps-using “ortho experts” will get you next to no responses if you have to hold to that.

James, 20 reply’s so far and you are the only one to put out a number.

 

[Jamt]

James, 20 reply’s so far and you are the only one to put out a number.

In a normal race SL turn knee angulation (i.e. rotation around ankle subtalar joint and femur head) is usually less than 5 degrees. For faster events it is smaller.
In low force turns you could use significantly more, but it is probably not a good habit to create.

 

[Sherman89]

According to yesterday’s trial with the Carv my maximum ski angles was 78 degrees in high speed GS style turns and I am trying to figure out what degrees of edge angle the ankle and knee generated and how much was hip angulation. But since no one including me can produce those numbers I have decided to scrape the question. My next question would be how accurate is the Carv but I will not ask.

 

[Fuller]

According to yesterday’s trial with the Carv my maximum ski angles was 78 degrees in high speed GS style turns and I am trying to figure out what degrees of edge angle the ankle and knee generated and how much was hip angulation. But since no one including me can produce those numbers I have decided to scrape the question. My next question would be how accurate is the Carv but I will not ask.

Well it's a good question (your original one) but I doubt knowing the answer will do you any good. I'm a numbers guy on the bike and on the C2 Rower, those numbers matter if you want to improve. Ankle and knee angles by themselves are only part of the equation and may be 0 degrees at the point where the most pressure (G force) is being applied. In any case edge angles are a result of going really fast and turning really tightly in a controlled, precise manner. I'm sure you can feel it when a turn is working for you or not.

 

[James]

Why don’t you just stand there and tip them? Then see the numbers.

Here’s the Reid Thesis from 2010
A lot of what you want is in there. But definitions matter, Carve may be differrnt.

You can see CoM inclination is measured from between the skis, hip angulation from center of outside ski.

https://nih.brage.unit.no/nih-xmlui/bitstream/handle/11250/171325/reid%20phd%202010.pdf?sequence=1&isAllowed=y#page237

 

[Sherman89]

Why don’t you just stand there and tip them? Then see the numbers.

Here’s the Reid Thesis from 2010
A lot of what you want is in there. But definitions matter, Carve may be differrnt.

You can see CoM inclination is measured from between the skis, hip angulation from center of outside ski.

View attachment 191882

View attachment 191883

https://nih.brage.unit.no/nih-xmlui/bitstream/handle/11250/171325/reid%20phd%202010.pdf?sequence=1&isAllowed=y#page237

James, great information—thanks for posting the graphs.