How about we say it is the aggressiveness or tenacity of the edge hold/grip.
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[recreational tuning] Choosing base and side bevel angles
How about we say it is the aggressiveness or tenacity of the edge hold/grip.
There are a lot of ways to make even a good ski chatter. I won't go into any of them here, but the key is that the edge is able to acquire a good purchase on the snow/ice, and then is forced to let go. This catch and release can be slow or rapid.
Key point regarding 1:2 or 1:3, is with the 1:3 it is easier to get purchase in the first place. You could end up with chatter with a 1:3 that would take you considerably more effort to even get purchase with the 1:2.
You could also find chatter easier to accomplish with a freshly sharpened pair of skis than a dull pair.
I also note that a less aggressive edge angle ( total included angle at the edge, e.g. 87.5 for a 0.5: 3 tune is more aggressive than 89 for a 1:2) is easier to feather.
Key point regarding 1:2 or 1:3, is with the 1:3 it is easier to get purchase in the first place. You could end up with chatter with a 1:3 that would take you considerably more effort to even get purchase with the 1:2.
You could also find chatter easier to accomplish with a freshly sharpened pair of skis than a dull pair.
I also note that a less aggressive edge angle ( total included angle at the edge, e.g. 87.5 for a 0.5: 3 tune is more aggressive than 89 for a 1:2) is easier to feather.
Hey James, unfortunately I don't have the animated gif I know you are referring to. Maybe give a shout out to see if you can raise Bob?
Here are some links to a thread we posted in last spring (angulation feels like ) with discussion concerning Critical Edge Angle, Inclination, & Angulation. Guess this stuff never gets old and maybe some content there to bring into a few current threads:
https://forum.pugski.com/threads/angulation-feels-like.4672/page-9#post-111555
https://forum.pugski.com/threads/angulation-feels-like.4672/page-10#post-111724
https://forum.pugski.com/threads/angulation-feels-like.4672/page-11#post-112557
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Found it. That was the thread where you caused oisin to flee. Maybe he'll come back...
Since the thread was locked, largely due to your shameless use of facts against long held beliefs, I can't use the quote function. I removed the other post quotes to save space and avoid having to requote for clarity.
90 deg or less between the line of action and the ski base. Ski holds. More, slips.
It's the 2nd one.
https://forum.pugski.com/threads/angulation-feels-like.4672/page-10#post-111724
-------------------------
Hi oisin,
While it may be a simple way to describe or think of the concept. It does fall short of being entirely accurate.
For starters, while the relationship between the ski base and inclination of the leg might be close and a fairly narrow range, that range - while small - is significant. So close does not count for this one.
For example, your statement: “You engage your edges (or release them( by tilting them (with respect to the snow surface).” Is incorrect …although most do believe this to be the case.
In fact, your edge engagement is determined by the relationship of your ski base to to the line of action or the force you apply to the ski. NOT the ski base to the snow. This is referred to as platform angle with 90* being critical edge angle or the maximum angle at which your ski will hold. If the base of your ski is 90* or less to the line of action then your ski will hold and if this angle is greater then 90* your ski will slip.
In practice you can regulate this by the use of angulation and/or tension in the ankle which is a very small amount of movement relative to the inclination available in your proposed method of tilting the leg, however, this small amount of precise movement has a significant role managing our platform angle to be plus or minus 90*. Thus determining if our skis are slipping sideways or not.
Consider then your statement: “If you are standing with your legs oriented vertically on a slope your edges are engaged.” This may or may not be correct and would only be the case if the platform angle is 90* or less; the base of the skis are not automatically 90* to the line of action because the legs are vertical, simply relax your ankles and you will be side slipping. Or alternatively, keep your ski base at the same angle to the snow and tip your legs into the hill and you will begin to slip once your platform angle exceeds critical edge angle.
...
So, this “theoretical line” is somewhat important; I would say more so than the arbitrary angle of the leg which does not accurately relate to either the angle of the ski to the snow (edge angle) nor to the platform angle. As far as I can tell the angle of inclination of the line of action is determined as prescribed by your link thus I presume accepted by the scientific community?? …but I don’t know.
As a related sidebar or continuation on the pivot slip I would consider an alternative way of looking at the body movements vs what you have described above. Consider moving the body down the slope as you turn the skis into the fall line so they do not run away from you when straight running (gliding), and conversely moving the body back to balance against the greater resistance underfoot when you turn them across the fall line. The resistance underfoot varies as the skis are rotated, but I always want to be slipping/disengaged and never “engage” edges while doing pivot slips. Slip fast, pivot slow.
Best regards,
Chris
------------------------------
https://forum.pugski.com/threads/angulation-feels-like.4672/page-10#post-111724
Since the thread was locked, largely due to your shameless use of facts against long held beliefs, I can't use the quote function. I removed the other post quotes to save space and avoid having to requote for clarity.
90 deg or less between the line of action and the ski base. Ski holds. More, slips.
It's the 2nd one.
https://forum.pugski.com/threads/angulation-feels-like.4672/page-10#post-111724
-------------------------
Hi oisin,
While it may be a simple way to describe or think of the concept. It does fall short of being entirely accurate.
For starters, while the relationship between the ski base and inclination of the leg might be close and a fairly narrow range, that range - while small - is significant. So close does not count for this one.
For example, your statement: “You engage your edges (or release them( by tilting them (with respect to the snow surface).” Is incorrect …although most do believe this to be the case.
In fact, your edge engagement is determined by the relationship of your ski base to to the line of action or the force you apply to the ski. NOT the ski base to the snow. This is referred to as platform angle with 90* being critical edge angle or the maximum angle at which your ski will hold. If the base of your ski is 90* or less to the line of action then your ski will hold and if this angle is greater then 90* your ski will slip.
In practice you can regulate this by the use of angulation and/or tension in the ankle which is a very small amount of movement relative to the inclination available in your proposed method of tilting the leg, however, this small amount of precise movement has a significant role managing our platform angle to be plus or minus 90*. Thus determining if our skis are slipping sideways or not.
Consider then your statement: “If you are standing with your legs oriented vertically on a slope your edges are engaged.” This may or may not be correct and would only be the case if the platform angle is 90* or less; the base of the skis are not automatically 90* to the line of action because the legs are vertical, simply relax your ankles and you will be side slipping. Or alternatively, keep your ski base at the same angle to the snow and tip your legs into the hill and you will begin to slip once your platform angle exceeds critical edge angle.
...
So, this “theoretical line” is somewhat important; I would say more so than the arbitrary angle of the leg which does not accurately relate to either the angle of the ski to the snow (edge angle) nor to the platform angle. As far as I can tell the angle of inclination of the line of action is determined as prescribed by your link thus I presume accepted by the scientific community?? …but I don’t know.
As a related sidebar or continuation on the pivot slip I would consider an alternative way of looking at the body movements vs what you have described above. Consider moving the body down the slope as you turn the skis into the fall line so they do not run away from you when straight running (gliding), and conversely moving the body back to balance against the greater resistance underfoot when you turn them across the fall line. The resistance underfoot varies as the skis are rotated, but I always want to be slipping/disengaged and never “engage” edges while doing pivot slips. Slip fast, pivot slow.
Best regards,
Chris
------------------------------
https://forum.pugski.com/threads/angulation-feels-like.4672/page-10#post-111724
"In fact, your edge engagement is determined by the relationship of your ski base to to the line of action or the force you apply to the ski. NOT the ski base to the snow. This is referred to as platform angle with 90* being critical edge angle or the maximum angle at which your ski will hold. If the base of your ski is 90* or less to the line of action then your ski will hold and if this angle is greater then 90* your ski will slip."
I'm trying to translate this...
I think what he calls the "line of action" I would call the "applied force vector", this vector is not always perpendicular to the ski base.
If you think about carving a chip with a chisel, you are not only pushing along the axis of the chisel, you are pushing down too.
If you don't push down some, the chisel won't cut no matter how sharp.
I'm trying to translate this...
I think what he calls the "line of action" I would call the "applied force vector", this vector is not always perpendicular to the ski base.
If you think about carving a chip with a chisel, you are not only pushing along the axis of the chisel, you are pushing down too.
If you don't push down some, the chisel won't cut no matter how sharp.
Yellow line from CoM-->BoS is line of action shown on left hand picture:
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Yes, if that angle is less than 90deg the ski holds, greater it slips.
My question, what about base bevel? Is it a factor in slipping/holding vis a vis the 90deg?
Yes, it is a factor. It would be the relation of the line of action to that beveled edge. So imagine cutting a platform into hard ice, with 1* base bevel critical edge angle is 90* to that beveled edge & thus 89* to the base ...but the base really doesn't matter as it is not really part of the equation.
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So, no base bevel means the least amount of inclination to get the ski to hold. Using the com definition for inclination.
There’s another definition?
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The new one below. No mention of com, line of action, base of support. Therefore Bob's diagram above is.... Well not mentioned.
Move to Canada!
Edit: that def is over simplified...
Edit: that def is over simplified...
Last edited:
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So simple yet so far to go. Occam cut his wrists...
Here is the csia, as posted by @Jilly (could be a ruse to get us to move to Canada)
Which puts into words what @Chris Geib lovely diagrams show!
If conditions are soft, any edge will work. As conditions get harder (and they do at places and times, especially in a season like this one has been so far) the difference between a 2 and 3 degree edge is clearly apparent to me.
So my bottom line is: when it doesn't matter I don't care, and when it does matter I care a lot.
Skiing my new skis with a 2 degree side angle yesterday, and a 3 degree side angle today was night and day. The difference in edge engagement and grip was obvious to me, and important at several moments today (Despite the fact that we had *more* fresh snow today than yesterday).
If not double blind with a control, the "night and day" difference, is just that.
Over night and the next day.
It's SCIENCE!
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Agree. Too darn binar for me unless I'm skiing on snow so hard that I just want to go to the bar for lunch, then head home.
And yes, it is awesome to agree with somebody that is undoubtedly FAR better at this sport than I am.
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