The light gets its medium and low brightnesses by interrupting the current going to the LED (all LEDs do this, btw). If you waved the light around, you would see a very fast strobe effect. Somehow, the circuitry makes enough radio frequency noise to interfere with the radio band that the Strada Wireless used, and it basically jammed the signal from the speed sensor. On full brightness, the power is uninterrupted, so there's no extra RF noise being created.

The Neuro uses a different frequency band (2.4 GHz) and is digital, so it's pretty immune to interference.

My road bike has a Flight Deck on it now, but if I change computers again, I'll probably go back to the wired Cateye Strada that I got the first time. All I really want to know now is mileage and time of day.