I have a Cateye Strada Cadence Wired Computer on my bike, and for some reason the speedometer keeps breaking. This is my second unit and I only had maybe 30-40 miles logged on the computer. The computer still senses cadence without issue. The first time it broke after maybe 130 miles.

I've tried just moving a magnet in front of the sensor to simulate revolutions but nothing happens. Sometimes if I go over big bumps in the road the sensor starts to work again.

Is there any reason why my Strada keeps breaking?