OpenGradeSIM is an open source incline simulator for indoor bike trainers
November 25th, 2019—
Although he would probably rather be outdoors, after an injury Matt Ockendon had a lot more time to ride his Tacx Neo indoor trainer and tinker. He decided he wanted his rig to be able to simulate the grade of hills, but as commercially available units with this capability are quite expensive, he instead devised his own solution dubbed “OpenGradeSIM.”
Ockendon’s OpenGradeSIM utilizes a Nano 33 IoT to gather power and speed data from his trainer over BLE, then calculates the grade that would be needed to produce such results.
With this data in hand, the Nano controls a linear actuator using an L298N-based driver board to raise or lower the bike’s front end. The derived bike angle is sensed via the Nano’s built-in IMU, providing an elegant closed-loop system. Additionally, the incline is shown on a 1.3″ I2C OLED display that serves as a mini dashboard while Ockendon cycles.