Kangaroo cycling shoes (aka Pair Number 28)

These are custom shoes with an extra hidden feature for riding a bike with clip and strap pedals. (Who doesn’t like extra hidden features?) This pair is also reinforced with a polymer fiberglass laminate that runs the full length of the insole. It is very thin and provides only a little extra rigidity. The cycling structural emphasis for this pair was to prevent deformation by the force on the pedals while maintaining flexibility on the crease line (decent walkability).

For those of you who were around in the days when I said I would never make a pair of shoes in black, apparently times have changed. This is my second pair in black. I have my issues with black, but my bias aside, black is difficult to photograph well.

In cutting the slot for the pedal to lock in, it was a challenge to make sure the alignment was correct and the toe of the shoe did not rub up against the toe clip at the front of the pedal.

Measuring the length was part of it, the other part was getting the slot position as close as possible to the crank arm while not having the shoe rub on it or have the heel hit the chain stay.

Here’s the view of the bottom with the pedal attached. I’ve also included the view from the front with toe clip to give you some idea of the ~3mm setback from the toe clip.

The leather used for the upper is vegetable tanned kangaroo, with veg tan cow liner. There is a deep red foot bed liner from veg tan goat that you can’t see from the pictures. It was not my intention to use kangaroo from the start, but due to some problems with the first uppers I made, I had to go get some more veg tan Italian calf on short notice and couldn’t find any. So I used kangaroo.

Are kangaroo cycling shoes for you? I’d heard kangaroo is tough stuff, but that’s not really enough. Tough, how? Inquiring minds want to know. Is this just kangaroo leather industry jargon? The wikipedia page on kangaroo leather gives some good information, but the links to the study are broken. There is an Australian RIDC publication available as a PDF that will tell you more then you probably ever cared to know about both bovine (cow) and kangaroo leather. Really, the heart of the matter is something like this (requoting wikipedia on the elusive morphology study):

The collagen fibre bundles in cattle hide are arranged in a complex weaving pattern. The fibres are often at angles as much as 90 degrees to the skin surface. Cattle hide also contain sweat glands, erector pili muscles and a distinct gradation in elastin levels, concentrated in the upper part of the skin.

Kangaroo on the other hand has been shown to have a highly uniform orientation of fibre bundles in parallel with the skin surface. It does not contain sweat glands or erector pili muscles and elastin is evenly distributed throughout the skin thickness (Bavinton et al 1987). This structural uniformity explains both the greater tensile strength of the whole leather and the greater retention of strength in splits. Bovine skin is much more complex in cross section. Hence in whole section it has many more weak point from which tears can start when placed under tension. In addition when sliced into splits the collagen fibres running at significant angles to the skin surface will be cut. These then become weak points in the structural strength.

The bottom line, especially now having worked with it a bit, is that kangaroo is in fact pretty tough stuff. Thanks to Ken at Renovo Bikes for cutting the slots on his table router, and for taking these pictures while my camera is overseas.