The definitions of camber seem to vary depending on who you ask.lilcliffy wrote: The E-109 is much stiffer, and more resistant than the Eon- but is it truly double-cambered? Was the Rebound truly double-cambered?
To me, and I've stated this before here, double camber means two different concave curvatures formed into the side profile of the ski. It is possible that the second curvature is so large a radius and/or so small an actual height that it is difficult to see.
I can see double camber relatively easily by sighting a ski. On some of those mid-width skis, if it's there, it's almost nil.
You can have a single cambered ski that has preserved wax pocket. The thing with a double camber ski is it will have a really strange camber flex - it will have a step change (it's never really a step change, but very abrupt) in stiffness when the first concavity is flattened and the second is loaded.
In terms of XC skis today, the little I have studied they look at the flex pattern far beyond this. With the right equipment it is possible to study the tip and tail pressure distribution under different loads and deflection. This is penultimate in ski tuning for different conditions. I'm not afraid to admit I don't understand it in the least.
I try to quantify the ski in a few different metrics:
- camber height and stiffness, whether double or single
- flexion during reverse camber. This includes tip and tail stiffness, although I don't always look at them independently.
- torsional stiffness i.e. how easy the ski twists about its longitudinal axis. Wider skis have more leverage in this respect therefor need more torsional stiffness to equal that of a thinner ski. It's not very difficult to measure this, but I never have. I usually just grab the shovel/tail and middle and feel it. I'm not sure I really comprehend it much for slow speed skiing in 3D snow - this is typically what I ski with these skis.
Ideally you could measure all these things in great detail but a few things seem to ring true. True double cambers create terrible reverse bending flexion. Even if the tip and tail are relatively soft and reverse, the center is so stiff it doesn't do much. I suppose in deep enough snow this approximates a smooth arc, and the ski turns smoothly. On more planar snow, this really can be a challenge to overcome... hence a lot of the pouncing and jumping. That helps initiate a ski that has little sidecut but also jumping on the ski bends a very resistant ski.
