Diana Riesler's bio-mxc² story

Article by Herbert Krabel on slowtwitch.com

Diana Riesler won Ironman Lanzarote and Challenge Poznan this year, but this German pro triathlete has a unique foot dilemma and that makes getting correct cycling shoes a tricky enterprise. Her feet are rather small at a size 6 UK, but according to her coach and fitter Jo Spindler she also has a "hallux abducto valgus (HAV) deformity at both joints of her big toes, but especially at her right foot. Her bone and tissue structure is hyper-flexible, soft and movable in all directions, and her arch sinks a lot under continuous load. Furthermore, Riesler has a misalignment of her os naviculare in both feet, where her naviculare is rotated in comparison to it’s normal position, so it sticks out of the medial plane of her foot."

For years she had to deal with stress fractures and other injuries as no shoe properly fit, but now after a long trial and error process with custom shoes she is finally on the right path, and has been injury free for 18 months. At the Ironman World Championships in Kona she will compete in the second generation of the Biomac shoes crafted for her by Götz Heine. A light offering in pink with a mid-foot cleat position.

Here are Diana Riesler's feet - the unique shape is readily apparent.

To get started on the custom shoes, an exact sketch of her feet was made. In length they are both equal, but the right one featured here is 97mm wide because of the aforementioned hallux valgus.

The left foot measures only 90mm wide at the same location.

Diana Riesler's troublesome right foot next to the very narrow Giro in her size, which she used to wear. Width of that one is 86mm.

The first carbon shell was created based on the sketches of her feet. More measurements were taken at that point to ensure there was enough space on top too. 

After some modifications to the carbon shell, a test upper was attached. Shown below in white.


With the lessons learned from the first version, a new carbon shell was made and thus the pink model was created. This one fit Diana Riesler like a glove.


Customized carbon insoles from MEDI Carbon Insoles rounded out the package. The spacers allow the sole to be set exactly in the position the fitter requires.


Paula Newby-Fraser was one of the early adopters of the mid-foot cleat position, and we noticed Daniela Ryf in Dubai with that setup as well. Several other Brett Sutton athletes also subscribe to this position, as it gives the rider a less acute angle in the hips and knees.


Götz Heine is very proud of his work.

Diana Riesler on the Wahoo KICKR trainer, and the custom Biomac shoes from behind.


Diana Riesler out on the road aboard her Fuji Norcom Straight.

The pair of Biomac shoes weighs only 228 grams, and has a stack height of 3mm.

All images © Jo Spindler