as others have mentioned, there's no such thing as "safe" when it comes to leaving a bike unattended and locked-up on the street, ESPECIALLY in chicago, a city notorious for bike theft. there are lots of good and reasonable precautions you can take to hopefully increase the odds of not having your bike stolen, as pointed out by other posters in this thread, but make no mistake, "safe" is an illusion. you could go out and get the best u-lock on the market and a heavy steel chain to boot, and a professional chicago bike thief might just angle grind his way right through that stuff in a minute or less the very first time you lock your bike up. or you could ride your bike for a decade with that locking system and be fine.
it's all luck.
the best thing you can do to bring yourself good luck in chicago, especially with a nicer bike with an attention grabbing brand, is to minimize the amount of time you leave your bike left unattended out on the street. if i were you, i would be begging and pleading with my employer to find an off-street bike parking solution so that my LHT wasn't sitting out on the street for hours and hours on end each and every workday.