My front light stop working consistantly. 1/4 of the way into my commute I'd have to turn it back on. It stayed working at that point, though. When I had time (remembered) I opened it up. The batteries fell right out of the unit. They were clearly not being squeezed in there tight enough. I did some light surgery on the paper-thin lead and it appears to be okay now but still the batteries feel a bit loose. I wonder if this isn't the inherent effect of the flex needed to keep the light in the spokes. THAT, and the relatively strong pressure needed to turn those bad-boys on/off.