We have been having a fine old discussion about ski flexing and energy storage.
I decided to make some measurement of ski stiffness to add to the discussion.
Boy, have I gotten a surprise.
Here is the setup
The carbide blocks each weigh 7 pounds.
The span between contact points is 156 cm.
Here is the Data.
Volkl P40 F1, 182, 21 m
Spring Constant, (lb/in) = 24.3
Camber, (in) = 0.65
Volkl Racetiger, 173, 16.4 m
Spring Constant, (lb/in) = 22.3
Camber, (in) = 1.10
Atomic LT-12 Race Stock, 176, 46/34 flex, 21 m
Spring Constant, (lb/in) = 23.9
Camber, (in) = 0.30
Kastle RX, 176, 16.4 m
Spring Constant, (lb/in) = 22.9
Camber, (in) = 0.53
Now this is a bit of a surprise.
The P40's have three sheets of metal and have a reputation for being unbendable by all but the strongest.
The Atomics are supposed to be very soft.
I always thought the Racetigers were on the stiff side.
And the Kastles are pretty civilized compared to the Racetigers.
The biggest difference between these skis is the camber, not the stiffness.
There is nothing like real data to challenge one's own BS.
One thing I notice is that these skis tend to go non-linear in their spring constant at about 1" of deflection and not all in the same way. Some seem to increase in rate(Racetiger) and some seem to decrease in rate(Kastle).
Now I have some thinking to do about this since these skis act very differently on the snow.
Maybe next I need to measure the first resonant frequency of these boards and get some idea of their damping...????
I'm open to suggestions.
I would have lost money by betting the Racetigers are stiffer than the Kastles.
Edited by dakine - 3/15/13 at 2:49pm