I would never leave a nice bike locked up on the street in any urban area of the U.S, especially along the east or west coasts. I'm originally from the mid-Atlantic part of the U.S., and would not trust ANY bike lock ALL DAY LONG, while I was at work. You could get away with it a few times, and I would not hesitate to use a great lock to go inside a store or something that did not take very long.
I've personally had a couple of bikes ripped off back east, once away long enough to see a movie, and know many others that have as well. The theives that go for decent bikes steal them for the money, and know what they are doing. No lock is going to stop them. None. Keep the bike with you, even to the point of taking into your office and planting it beside your desk/work-station. In bigger or more public buildings, I would even suggest that you lock it to a desk or something inside your office whenever you are away from your desk for more than a few minutes (lunch, meetings, etc.).
Or you can do what I do, and commute on a really decent, but beat-up looking old race bike that has the same geometry as your "go fast" bike. You can lock something with flaking paint, downtube shifters, and a luggage rack (carry work clothes too).
Last edited by Pinyon; 11-27-07 at 09:40 PM.