Industrial standards are a mixed blessing (e.g., it’s required quite a bit of designer skill to keep Dynafit bindings and boots working well together while having the boots conform to the ISO standard.) Yet on the whole, our gear would be reminiscent of stone age eating utensils if we didn’t have agreement (informal or otherwise) among manufacturers to stick with certain standards
Thus, when we’ve got questions about the boot/binding interface — or just wonder the “why” of a given boot feature, we find ourselves frequently referring back to ISO 9523:1990, the “DIN” standard for “Ski Touring Boots,” (telemark boots have a separate standard).
What got me thinking about this is a recent question we got about someones Marker Duke bindings seeming to place damaging pressure on their boot’s heel shelf. Also, a few blogs ago we brought up the issue of toe wear from hiking in randonnee boots, and how thicker rubber could fix that. Thus, for “mission: summer blog” I figured publishing more equipment backstory would be a nice way to add something to the great knowledge bank.
|Side view of ISO ski touring boot heel dimensions shown above. Somewhat common issues with AT backcountry skiing boots are things like the binding heel not closing when you step down, or the boot having vertical play once the binding is closed. If you get any of those symptoms, check your dimensions based on the ISO drawing above. For example, see that the vertical thickness of the sole heel is 32 mm +- 3 mm (measure by placing boot on a flat surface and measure up from surface. If your binding is acting funny and your boot is within this spec (many of ours measure at 30 mm) then look at the binding for problems such as having the wrong length or forward pressure set. If the boot is out of spec or at the extreme end of the range, then consider fixes such as grinding to reduce thickness (rarely necessary), or re-soling if your boots are worn from dirt hiking (likely).|
|ISO boot toe dimensions shown above (side view). One of our pet issues here is that most AT boots could have more rubber at the toe, where most wear happens while walking. As shown in the diagram, this would be easy to accomplish while sacrificing some rocker. Many soles could even be made overall thicker (most of ours measure at around 28 mm), but doing this can be difficult in the case of Dynafit bindings, as the amount of sole below the Dynafit fitting is critical in how the binding operates.|
An update to ISO 9523:1990 is in the works. According to sources it’ll have nearly the same if not identical dimensions, but define a sole that has solid areas that work better with binding support points (AFDs). The new standard is 9523:2008 (later digits are the standard’s date).