If you ride your bike in Chicago, eventually you will have to lock it to something outside. Even cyclists with an empty garage and a place next to their desk at work need to stop and buy milk or something on the way home sooner or later.
A brief look at the Chicago Stolen Bike Registry quickly tells you the most important factor to prevent bike theft: actually lock it to something. Most of the bikes stolen seem not to have been locked to anything. They were left unlocked for just a minute, or they were in locked garages or backyards or bike rooms or porches and considered safe. So even if you won't be a minute or your bike is in a locked space, lock it to something too. (This happened to us once when a house one of our bikes was in got broken into - keep your eyes open for a red and black Brompton Mk-2 T-5 with a 5-speed Sturmey Archer hub? :-)
The second most important thing seems to be: Don't use a cable lock. Bikes locked with cables are more often stolen than others. We've been over locks in another post, with recommendations for locks we like. We don't like combination locks either but maybe you do.
So where can you lock your bike safely?
Wooden railings and trees are no-nos of course, and metal fencing is easy to cut (wire fence) or smash (cast iron), so of course you wouldn't use those. This generally includes the little fences around trees and planters downtown too. The giant-staple-like loops that the City puts on the sidewalk are supposedly pretty good (though we know of one that pops up off its base - was it on Randolph Street near the El?). Even they are not infallible. We use them a lot.
If a city bike rack is unavailable or full, you often need to lock to a city pole.
Sucker and Other Poles:
If the pole isn't secured to its base, you've found a Sucker Pole like the one at the top of this post. Look! Someone could just twist it, lift it up and throw it on the curbside. If you park your bike to it, kiss your wheels goodbye before you go. Don't be a sucker! Here's what it is supposed to look like --->
But just since it's not a loose, removable Sucker Pole doesn't mean it's perfectly safe. A sign post, like this one that's bolted down, might be OK in a pinch, but all the thief has to do is cut or unscrew that bolt, lift the pole, and throw your bike into the van, so maybe you'd be happier with something a little more substantial.
A Substantial Thing to lock to:
|This one is a good choice.|
Once the first bike is secured, we'll often bend the rules and lock any other bikes we have onto the first bike's chain and frame. Generally we'll also use a second lock on everything if we can. We try to use the side near the street so we don't block pedestrians.
Old Parking Meters (left as a convenience to cyclists)
These old meters, left from the good old pre-Daley-parking-meter-fiasco days of 25-cent-an-hour parking, are as good as they ever were to lock to. Unfortunately, you have to have a U-lock that is narrow so it cannot under any circumstances be lifted over the head of the meter, yet wide enough to fit over your frame and wheel. Tricky. Chains and so on just lift right over. And these meters are usually near a streetlight anyway. And sometimes, they're Sucker Meters; check if they wiggle or twist. We don't use them.
CTA and other bus and train services are not as bike-parking-friendly as you'd think:
|Never lock to a CTA pole!|
Here, we'd use the green one behind it.
I think Metra and other transit services in the Chicago area have similar policies, so I don't lock onto their stuff either. RTA has a summary page but it doesn't get into locking up your bike. Be careful using the CTA bus bike carriers, too - someone got run over unloading a bike, so tell the driver first, and sometimes your bike can fall off.
Look at racks before you trust them to keep your bike safe:
|Country Rack visits the Big City|
The Stolen Bike Registry and Chainlink have more ideas, including not leaving your bike locked for a long time, overnight, or in a high risk place (like near a Metra or CTA station). Lots of the bikes that are stolen are new or at least look new. Maybe a used one is safer? Who knows what the thief is looking for.
It apparently takes a professional thief something like 30 seconds to steal most bikes, so making yours less appealing and more difficult to cut free may convince the thief to go to the one next to yours instead. Or not. Just do your best.