Bikes Suck

The past two days my bike chain has fallen off twice. Luckily i wasn't too far from where i needed to go so it all worked out. But today something weirder happened. While I was WALKING my bike on the way to the DC for lunch, I heard a poof! It shocked me to see that my rear bike tire was instantly flat. I wasn't even putting pressure on it and i didn't run over anything, it just felt like spontaneously popping. I don't even have a clue how it happened. I guess I should just take the bus next time...