|Originally posted by disski:
Chatter will affect me without affecting edge-hold.... I NEED to feel the ski travelling to be able to balance & move....
A 'noisy' ski is a pain in the butt for me - makes all movement and balance that much harder.
I just am struggling with why edge hold is so linked with chatter for you...
I have skied on terribly chattery noisy things that held an edge just fine... they were just DOGS to ski on because they made so much racket under my feet I could not feel the snow...
You are correct that some types of vibration of the ski minimally impact edge hold. On the other hand, other types of vibration seriously impact it. As I said in an earlier message in this thread, the effect of chatter on edge hold is highly dependent on the amplitude of the motion, the shape of the vibration (ie, where the "nodes" are), and the frequency.
In the sideslip test I described earlier, I saw a very low frequency (one or two cycles per second), large amplitude, long wavelength vibration of the ski. Specifically, the tips and tails of my 9.16's moving an inch or two up hill (relative to the mid section of the ski), then suddenly releasing. When they were moving up, they were holding on the ice, and the downhill motion of my CM was slowed. When they released at the end of each cycle, the downhill motion of my CM speeded up. This particular vibration CLEARLY was negatively impacting my edge hold in this test.
My logic in presenting it was that you look for the largest, most obvious problems first. If I was seeing a negative effect on edge hold in a zero forward velocity sideslip, I am virtually certain that many skiers will see the same effect in normal skiing whenever the angle of attack is becoming significant (ie, when there is significant skidding to a turn).
Higher frequency vibrations (ie, the type we normally think of as chatter) can have a similar (if less obvious) effect. If the surface is glass-like smooth ice, even tiny (sub mm) vibrations of the ski, if high enough in frequency can lift portions of the ski out of the little groove in the ice they have been riding in and reduce the overall grip. As the surface gets more irregular (but still hard), even if the ski is not chattering, you will only have a fraction of the edge in contact with the ice, so the effects of an equal ammt of vibration can be fractionally less.
Highly damped skis minimize the vibrations and keep lots of edge in contact with the ice. However, many good skiers feel such skis are "dead" and simply don't like them. Many will make the exact opposite statement of what you said, and will say that they can't feel the surface unless there is some vibration.
Mfgrs try to walk a balancing act to try to make a ski that retains some liveliness but whose edge hold is not reduced by "bad" vibrations.
With respect to your statement, "...I just am struggling with why edge hold is so linked with chatter for you...", I assure you that it is not just me. I have to run to teach, but there is an excellent discussion of this whole subject in "The Physics of Skiing" by Lind & Sanders, particularly, the section starting on p. 60., e.g.,"... An underdamped ski will vibrate too much and chatter, or worse, release the edge entirely, so that the ski is out of the skier's control ..."
Sorry. Gotta run. More in a couple of days.
Tom / PM