I got a rude shock when I returned to my bike at the 95th St. Metra station after work yesterday. The bike was perfectly fine when I left it in the morning. When I unlocked it from the rack at the end of the day, the front tire was flat. An almost-new Schwalbe Marathon Plus had been sliced along the sidewall. This wasn't in a spot when somebody could casually poke it in passing. Whoever did thi…