The world of power measurement has exploded in recent years. There are more ways to measure power than ever (cranks, pedals, bottom brackets, hubs and more) and prices have been steadily decreasing. That’s all great for a cycling enthusiast, $500 for a Stage power meter actually sounds cheap to us. But for the more casual or cash strapped rider, power meters are still far too expensive. But for $30 in parts, some know how and a little elbow-grease, you could build a power-measuring bike pedal.
A user [rabbitcreek] over at Instructables did just that. A lot of thought and engineering went into the pedal pictured above. Measuring the force applied to the pedals falls to a pair of micro load cells connected in parallel and a Wemos provides the wireless connection. The pedal is powered by an HX711 load-cell amp with a small LiPo pack. Charging is handled by a charging module connected to a Qi wireless charger. A Hall sensor for measuring RPMs, a rugged power switch, and some Neopixels round out the build.
After stuffing all the parts in a modified mountain bike pedal, he potted the whole thing in epoxy for all-weather use. Overall, one of the coolest DIY cycling related projects I’ve ever seen.