Technical FAQ: Do bigger shoes make for faster riders?

Dear Lennard,
I can’t help but notice that some of the taller riders, Chris Froome among them, seem to have unusually big/long feet and shoes. This is not limited to Froome or even riders tall in stature, and it appears to be disproportional. My question is, from a biomechanics and physics standpoint, does this offer riders greater leverage and power with the increased length? If so, would this encourage riders to wear larger shoes than they would off of the bike, given the improvements in stiffness and weight of carbon soles. Finally, should the UCI regulate shoe size “fudging?” (I know that last question might raise the ire of some readers.) Again, I am not signaling out Chris Froome; to me the phenomenon across the peloton raised the question in my head.
— Joe

Dear Joe,
I don’t think there is a way in the world that it could be an advantage to ride with a longer shoe than your foot size would demand.

First off, I think that controlling a longer lever (i.e., from the heel to the pedal cleat) with the calf muscles is mostly wasted energy. The power to propel a bicycle primarily comes from the quads, glutes, and hamstrings. Developing those muscles makes sense. However, developing bigger calf muscles in order to flip a longer shoe downward would result in a net loss in speed, in my opinion, by adding more weight to the lower leg (which moves faster, in a bigger circle, than the upper-leg muscles), thus costing energy with minimal propulsion gains.

Also, the longer the shoe, the higher the saddle has to be to get the same knee and hip angles at the bottom of the stroke; the longer shoe makes the effective leg length longer. A higher saddle results in more aerodynamic drag and a higher center of mass, resulting in more power required to maintain the same speed and reduced cornering and bike-handling effectiveness.

Most of the custom bikes I build are for extremely tall riders. As you might imagine, they generally have big feet. I try to create the opposite setup with them from the one you are proposing. Based on my personal experience as a tall rider with big feet, I always recommend that riders with big feet push their cleats back on the shoes as far as they can.

Mountain-bike shoes allow the cleats to go farther back than do most road shoes. On MTB shoes, this means using the further back pair of threaded holes in the shoe plate and sliding the plate back as far as it will go in the two sole slots.

On road shoes, there is only so much you can do, unless your shoes have slots on the three mounting holes. In my case, I use Speedplay Zero pedals with the “Cleat Extender Base Plate Kit” under my cleats. I slide the extender plates back as far as I can on the shoe, and then I mount the cleats using the rearward set of holes. This results in my cleats being 14mm further back than the furthest I could get them back without the plates.

The far-back cleat allows me to run a lower saddle, thus getting lower to reduce wind drag and improving handling. Having the cleat so far back also greatly reduces “hot foot” pain under the metatarsals; this is how I take advantage of the rigidity of modern carbon shoe soles — distributing the pressure of pedaling over the entire foot, rather than concentrating it under the ball of the foot. I also have a painful condition (developed from years of cycling and cross-country skiing?) called “Morton’s neuroma” between my metatarsals, and the far-back cleat is part of the solution that allows me to ride pain-free.

I think it is merely coincidental that Chris Froome happens to have big feet (and hence big shoes) and wins the Tour and Vuelta. Rather than being an advantage he capitalizes on, it may be something he overcomes. I think the UCI should not devote any resources into catching “shoe fudging” and instead direct more resources into its testing for hidden motors.
― Lennard