All of a sudden yesterday my cycle computer decided to flip out and register approximately twice the likely speed. About 1/4 of the way into our 50 miler (after averaging about 9-10 mph in very muddy, wet conditions) it was reading 19 to 20 mph and even higher, needless to say the miles ticked away at about twice the rate they should have too. The display isn't faded nor is the a low-battery indicator flashing. Is there any reason it would have suddenly come out of calibration? Or, is it more likely that the battery is dying? Both sensors seem fine and it's always been weatherproof and reliable. It's and Echo F1 that's about 3+ years old.