Found this bike brake light from a news article that popped in my newsreader and it’s quite interesting. LucidBrake inventor, John Craig, is improving his current tail light system that works on de-acceleration with a new TI inductive sensor and entered it in a TI design contest
The sampling rates available on the TI LDC1000 provide hundreds to thousands of readings for each spoke’s transition near the sensor, even for the fastest bicycles. The threshold output on the INT pin provides the perfect way to determine very accurate bicycle velocity - a simple microcontroller count between pulses does the trick. When velocity is decreasing at a significant rate, the brake light comes on.
Like LucidBrake, this inductive sensor could inspire other, new ideas from bike makers to calculate a bike’s velocity. From those measurements, a new simple power meter perhaps?