WHAT IS THE DIFFERENCE BETWEEN BOOT STIFFNESS AND FLEX or... ARE THEY THE SAME THING?

Alpine riders sometimes confuse shell stiffness with ankle flex or pivot. Let me try to clarify those two points.

Shell stiffness can be defined as the rigidity created by the type of material used in the manufacturing and the design of the shell structure itself. If there are areas of the shell that are thin, those areas may fold or flex more than areas of the shell that are thicker or have more structural support members. Similarily, if the material used to manufacture the boot is not rigid enough, the boot's overall stiffness may suffer.

Ankle flex can be defined as the mechanism that provides the means (and resistance) to allow fore and aft flex of the lower leg about the ankle's pivot point. This is not directly related to shell stiffness but can be affected by it if the shell is not very stiff.

The DeeLuxe LeMans (and former Raichle SB) series of boots are designed with a softer shell structure. There are few internal structural supports and they are also manufactured with a somewhat soft/flexible plastic material. The DeeLuxe Suzuka/Indy (former Raichle AF) series of boots have an "skeletonized reinforced" lower shell design that provides added stiffness in the areas of the shell that are prone to distortion and flexing. The Suzuka uses the same plastic material as the Lemans, while the Indy is manufactured using a more rigid plastic (adding to the boot shell's overall stiffness).

The ankle flex of the Lemans & Suzuka boots is controlled by tongue and liner stiffness (if the lean mechanism is left in walk mode). Ankle flex can be nearly eliminated by locking the boot in a given position with the 5 position lean mechanism. There will be a small amount of ankle flex even with the boot locked due to shell flex/distortion.

The ankle flex of the Indy boot is controlled by not only tongue and liner stiffness but an adjustable spring mechanism as well. This spring mechanism controls the amount of force necessary to flex the ankle forward (not back). Different spring stiffness can produce different force requirements. Again, some ankle flex is due to shell flex/distortion.

So what does this mean to the rider? When working with your boot fitter/professional, it's important that they understand what you're going to be using the boot for. For the most part, racing requires not only a stiff shell design but fully adjustable ankle pivot too. For the adult racer, the Indy meets these requirements. For those riders that want to hit the gates on occasion but prefer to focus on carving "C-shaped" arcs, the Suzuka hits the spot. This also holds true for the younger or lighter rider that may not be able to flex the spring-loaded ankle pivot of the Indy. If the occasional off-piste run is for you, then the LeMans' shell design with walk-mode ankle pivot provides for that.