The Same Mountainbike: I am a scientist & genetic engineer and I am always interested and fascinated in trying to understand how things work & why things do what they do, especially when they fail. 90% of what we do as biologists fails; we get used to failure, trust me. Hence, I have a very natural curiosity about what is causing these sorts of explosions. In my case, I don’t know what happened first - i.e., did the mirror crack and the release of the liquid/gel trigger some sort of electrical short/explosion that caused the whole mirror to come flying out of the casing OR did the explosion happen first, which then caused the mirror to crack? I can say, that in the San Fran bay, temperature fluctuations are infrequent. The day this happened, it was a classical SF morning, ~57 degrees, which is the norm (high 50’s to low 60’s) year round.