Part I - Cycling Shoe Design & Natural Foot Shape

As a Design Engineer one of my core beliefs is “form follows function.” This mantra is not new, it is credited to the American architect Louis Sullivan in 1896 [2].

 In this series of articles, I am going to illustrate this mantra and how it has been implemented in reverse in the shoe industry. I am passionate about this topic, I strongly believe in optimizing human health and fitness, and this is an area that is still in the dark ages, especially in regard to cycling footwear.

 In this first article, I am going to discuss how cycling shoes fail to achieve their most basic function: a comfortable interface with the human foot. I will support this claim by then introducing some basic evidence that has interrupted the natural development of our feet.

 First, consider some of the design requirements for a cycling shoe. This is not an all-inclusive list; my goal with this list is to highlight that even for something as seemingly simple as a shoe, there are many design criteria that need to be considered, and can be very complex.

•  Comfort: Today’s endurance road, mountain bike, and gravel events require all day comfort
• Power Transfer: The shoe needs to be stiff in the right places to efficiently transfer power to the pedals
• Secure Attachment: eliminate motion between the foot and sole
• Flexible I: The shoe also needs to be flexible for the relative changes in position of the human and the bike such as cornering, steep descents or accents, and maneuvering around or over obstacles 
• Flexible II: some level of hiking comfort may be needed when the accent is too steep or the minimum maintenance road is too muddy 
• Breath-ability: method to bring fresh air into the shoe and wick moisture out 
• Alignment: The sole or insole needs to properly align the foot to the pedal to avoid knee pain

There are some very innovative shoes designs that have very creative solutions for almost all of these design parameters. The example shown in Figure 1 is Giant’s Surge Pro shoe. Giant has developed what they call ExoBeam technology, I really like the concept of this technology, it is stiff fore/aft, yet allows proprioception of the ankle (or the heel can twist laterally), unfortunately, their basic shoe shape is really narrow, so narrow my foot won’t fit in the shoe at all, therefore I will never be able to learn if ExoBeam flex does what they claim. I am not picking on Giant, narrow shoes are extremely common in cycling footwear, and Giant is not the only brand I am unable to fit my foot into.

In the world of shoes, the mantra is fashion over function.
This fashion first mantra is the primary topic I am tackling in this series of articles. I will now present some basic evidence of this fashion first claim. No rocket science is needed here, simple basic logic will do it. First, I ask you to look at your bare feet. While looking at your feet consider the following:

•  Angle of your toes 
• Space between your toes 

Now, compare what your feet look like to the examples shown in Figure 2. Which shape of foot do you have? Figure 1A illustrates what your natural foot shape should look like and Figure 1B shows the deformation modern day shoes have molded your foot to look like.

Unless you are part of a primitive tribe that either doesn’t wear shoes, or wears sandals only, this was a trick question, your feet will look similar to 1B. One might now be thinking; wait a minute how do we know what a natural foot looks like? As proof that your feet should look like 1A, next, look at a baby’s foot shown in Figure 3, this is the natural shaped foot we are born with.

 If you are not convinced from the simple logic presented, here’s a link to some more scientific references from studies done in the past: https://www.correcttoes.com/foot-help/articles-studies/

So, if you now agree that our feet are deformed, then how is this happening? The answer is simple: narrow footwear. We all have been cramming our feet into narrow shoes our whole life. Every shoe you have ever owned was too narrow for you. Dress shoes are the worst, most have a pointed toe!

I would now like to circle back to Form Follows Function, this is a mantra I live by, and as a Design Engineer one of the ways I deliver robust and quality products to my customers, I inherently understand this as a Design Engineer. It doesn’t even make sense to design something to look good first and then do what ever has to be done to make it “functional.”

In summary, modern day footwear has a width smaller than the natural shape of a human foot. Due to cramming our feet into these narrow shoes, the natural shape of our foot has been deformed to look like the shoe shape.

Part II of this series will address advances that have been made in the running industry and how these same principles need to be applied to the cycling shoe industry, or wait, is there a company already doing it?

 References
 [1] Hoffmann, P., M.D., Cucuzzella, Mark, M.D., Kerrigan, Casey, M.D., Maffetone, Phil, PhD., McClanahan, Ray, PhD, , 1905, How Healthy are Your Feet?, NRC Media.
 [2] Sullivan, L. H., 1896, "The tall office building artistically considered," Lippincott's Magazine.