Originally Posted by kubagr
could you specifiy what do you understand under delta???
The delta angle is the additional height of the heel above the toe in mm. The manufacturers often build in this height in an attempt to help users get forward more. If you have too much tilt (or ramp angle as it's often known), especially when combined with the forward lean of your boots, it can be counter productive as you end up sticking your backside out to counterbalance & to stop that 'over the handlebars' feeling. Apparently most WC racers are using bindings that have little if any delta so it's then easy to tweak their set-up as required. It's not uncommon for people to actually balance best when actually slightly toe high. My ideal set-up is like this hence my shimmed solution as per the above pic. I used to have this solution built in to my boots by attaching a lifting plate under the toe but my new Atomics have a hollow toe lug that can't be routed back down to the proper din spec (19mm) so I had to go with the shims under the binding.
You can check easily your own set-up. Snap your boots in to your bindings & put the ski on a flat surface, pressing the camber down flat. Measure vertically from the flat to the bottom edge of your boot at the toe & at the heel, then compare.
The manufacturer's specs I listed above are based upon mounting their bindings on a level flat surface were in reality a ski tends to have a curved profile/thickness variation along it's length therefore your own specific binding/ski combination might be slightly different than stated by the binding manufacturer as the thickness of the ski will affect the relative heights.
Note that a smaller boot will give a steeper actual 'ramp angle' (ie forward tilt) than a longer boot in the same binding.