Lock on, Chicago.

If you’re biking the city this summer, you’ll need to invest in a good lock (or four, depending on how paranoid you are). Otherwise, you’re vulnerable to bike theft.

Bike theft is common in major cities, and all the more common in the summer months, when more riders are on the roads and the crime rate rises. The Chicago Police Department doesn’t track bike thefts separately from other theft reports, making it difficult to say how frequently thefts occur and where they’re most likely to happen.

But data from local websites dedicated to tracking bike thefts in Chicago suggest that a bike parked outside a Loop office could be just as vulnerable as the one you left out overnight outside of that bar.

And the problem is big. According to the Chicago Stolen Bike Registry, at least 34 bicycles and bicycle parts, like a seat or a wheel, were stolen in Chicago between June 1 and June 9, from CTA stops, backyards and basement storage rooms, among other locations. In 2012, the site logged more than 1,000 reports.

Kevin Conway, a year-round cycler and one of the volunteer administrators of the registry, said July is usually Chicago’s busiest month for reported bike theft.

His biggest piece of advice to bikers is obvious: Remember to truly lock your bike when you leave it somewhere.

“Something like over 70 percent of our reports in May were either not locked, or they were locked with some form of a cable lock,” he said. “They cannot use a cable lock as their primary method of locking, or their bike will be stolen.”

But whether you’re using a chain, a U-lock, or a combination of locks, Conway said a golden rule applies: “The trick for keeping your bike stolen is to be a less-easy target than the bike you’re parked next to.”

There’s no surefire way to keep your bike safe, but there are many ways to make it safer:

>> Register your bike’s serial number with the City of Chicago. If you don’t, you may not be able to prove you’re the bike’s true owner. You can usually find the serial number underneath the frame.

>> Lock the front wheel and the frame to the bike rack, using a reliable U-lock or chain. Some people lock their rear wheel to the frame as well.

>> Be careful if your seat has a quick-release mechanism; it could take someone just a few seconds to grab it and run.

>> If your bike is stolen, there’s a chance it might show up the following weekend at the Ashland Swap-O-Rama at 41st and Ashland.

And if you need more instruction...

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