Currently commuting 15 miles each way in NYC on a '91 Schwinn Paramount. Shimano rx100's (I've heard they're the equivalent of 105's but not sure that's true) and switched to a positive angle stem. It's comfortable and fine for now but doesn't quite fit me. I'll be looking to upgrade at some point. Rather than ask which bike is best, here's my question: what features do you think are essential on a commuter doing 150M/week in 3 seasons?