Shoe-based power meter could be on the way

A patent application has been published that suggests a cycling shoe system for measuring power could be on the way, although this is not the first time that a shoe-based system has been pursued

One version of the shoe mentioned in the patent application from Icon Health & Fitness has a pocket positioned in the sole below the ball of the foot. A platform that features sensors on both the top and bottom fits into the pocket, with a potentially waterproof cover and a cleat over the top. The platform will house force sensors (each of which will include a strain gauge), a torque sensor, a temperature sensor and an accelerometer.

“The accelerometer may allow the calculation of cadence or position of the sensor platform,” says Icon Health and Fitness. “This information can be correlated to other data measurements to analyse and visualise the forces generated by a user throughout the range of motion.”

The patent application describes how the positioning of various strain gauge sensors would allow the measurement of forces in different directions.

A processor and communication device will also be located on the sensor platform to take the information from the sensors and send it on to a computer via communication methods such as Bluetooth and Wi-Fi.

The patent application also mentions the use of a placeholder platform in certain circumstances, suggesting that a one-sided (left or right) power measurement system could be an option.

What about powering the system?

A replaceable or rechargeable battery could be located in either the heel or the front half of the shoe, or even that it could sit in a housing positioned externally to the sole. Other possibilities are that the power could come from a solar cell positioned on top of the shoe or that “the sole may include a kinetic energy converter to convert the cyclic movement of the shoe into an electric current”.

The cover shown in the pictures is for typical three-bolt road cleats, such as Shimano SPD-SL, although the patent application also covers two-bolt cleats, such as Shimano SPD, and four-bolt Speedplay cleats. It also mentions the possibility of using cycling shoes with platform pedals that don’t involve any cleat system at all.

Why measure power at the pedal when there are plenty of other power meter systems already on the market?

“Generally, a force measured closer to its source (eg the foot) will be more accurate than one measured further away from the source,” says Icon. “Therefore, a sensor installed on the crank will be generally less accurate than a sensor installed on a pedal, which will be generally less accurate than a sensor installed in the sole of a cycling shoe. This decrease in accuracy may occur at least in part because of the losses that may occur as the force transfers from the shoe to the pedal to the crank.

“By installing the sensor platform in the sole of the cycling shoe, the sensor platform is collecting accurate power information close to the foot of the user.”

One other advantage is that a shoe based-system would presumably be simple to use on multiple bikes without the need to swap components.

Will this system ever be produced? Thousands of patent applications are made and granted for designs that never make it to market so it’s by no means a given that this one will ever come to fruition. We fired off emails to Icon last week requesting further information but we’ve yet to receive a response.

Anyone who has been following developments in the power meter market over the past few years will know that Brim Brothers, a Dublin company that had been developing a cleat-based Zone DPMX power meter, ceased operations in 2016. 

The Brim Brothers system was designed to work with an adapted version of Speedplay cleats. Sensors inside the cleats measured the force between your shoe and the pedal, and your power was calculated from that information. 

However, the company said that difficulties it had with production quantities, together with variable accuracy of the finished units when in use, meant that it was unable to deliver and it didn't have the resources to continue.

That’s not to say that Icon won’t be able to make its design work, of course, but we’ll just have to wait and see on this one.

www.iconfitness.com