The prizewinning sandals I showed at the 2017 Pender Fall Fair and you see here were a test-bed. I purposely chose the leather for the arch strap from an area closer to the belly, so it is looser and more stretchy by definition. The same with the 4 layers of sole leather instead of 2. Some of the looser bridle cowhide would normally have been discarded or used for other purposes.
But I wanted to see how those choices would work in the real world, and perhaps not hew so closely to my traditional choices which take longer to break in (coming from a tougher, more firm part of the hide). Too much stretch, and the sandals fit sloppily, and that makes running and climbing more dangerous. That hasn’t proved to be a problem. However that small added loft makes for a slightly less secure step, and at-speed is more likely to occasionally allow the heel to twist.
The heels have an insert of clipped wool fleece that after 5 years of summer wear finally lost all of its loft, but is still comfortable.
The considerably wider arch strap requires multiple fittings, so the design isn’t practical to make commercially.
This design fits me comfortably, after the typical few weeks of occasional wear to stretch the straps. This is the way I recommend that your new sandals be broken-in.
