1. Some bike thieves are handy with power tools.

Maybe you already knew a cheap cable lock is no match for a sturdy pair of bolt cutters. Or that metal U-locks can sometimes be defeated using car jacks. But in the arms race between thieves and deterrents, a power tool called a cordless angle grinder is hard to beat. In a spray of sparks, this handheld electric saw can slice through metal — meaning even a decent U-lock might not be enough. Alas, there’s a tool for everything.

2. Organized crime is a factor.

Bike thieves operate on different levels. Some are low-level opportunists — they’ll grab a saddle or an unsecured wheel to make a quick buck. Others are much more sophisticated. They have not only power tools but also trucks, and places to store bikes that may end up for sale online — or in other cities. It’s not unheard of for bikes stolen in the Bay Area to turn up in Los Angeles or Portland.

Box Dog Bikes, in San Francisco’s Mission District, knows this kind of crime firsthand. In August, burglars broke into the store overnight and hauled away 21 bikes valued at more than $40,000.

3. Even so, bike thefts in S.F. are trending down.

Comparing the first nine months of 2018 to the same period last year, San Francisco police say bike thefts dropped 23 percent, from 572 to 441.

That could be thanks partly to outside factors, like the proliferation of bike-rental kiosks and scooters that enable people to risk their own bikes less. But police chalk it up to expanded foot patrols warding off some would-be thieves, along with newly centralized investigations aimed at stopping higher-level theft rings.

4. Stolen bikes are often swapped, then swapped again.

In some circles, bikes aren’t just a practical mode of transportation, but also a kind of currency. An intact bike is like a large bill that can be broken up into smaller denominations in the form of parts, and later reconstituted as a different ride.

This means stolen bikes and parts tend to change hands early and often — potentially complicating police work.

5. Hot bikes go for pennies on the dollar.

A bike that would retail for over $1,000 often goes for a lot less when it’s stolen. That’s partly because bike thieves may be eager to offload hot property for quick cash (see #4 above) and also because the bikes are often reconfigured in order to sell parts separately — or to hastily disguise a stolen frame, say, with a new paint job.

When athlete Canaan Vallejos’ stolen bike turned up on Craigslist, he managed to get it back — minus the racks and expensive saddle, which had been replaced with a seat so cheap he told me “they wouldn’t put that thing on a Huffy.”

6. Websites like Bike Index help people recover their stolen bikes.

Thousands of bikes have been returned to their proper owners thanks to people volunteering their time and keeping an eye out for bikes reported stolen in their area. With help from a tipster using Bike Index, Robin Lee, one of this week’s question-askers, managed to track down a customized mountain bike that was stolen out of her garage. (The police helped get it back, and SFPD recommends calling 911 if you have eyes on someone with your stolen bike.)

What do you wonder about the Bay Area, its culture or people that you want KQED to investigate? Ask Bay Curious.

7. SFPD has a warehouse full of stolen bikes whose original owners can’t be found.

An analysis found that in 2012, SFPD recovered 864 stolen bikes, but only 142 went home with their owners — about 16 percent. Asked if she could ballpark the current number of recovered bikes in storage, Public Information Officer Giselle Linnane told me “hundreds, yeah — at least.”

She says police often simply don’t have contact information for owners or a way to track them down — and that filing a police report improves your chances of getting your bike back. Bikes that can’t be returned are eventually given to charity.

8. There are many ways to help protect your bike ...

Some perfectly reasonable bike commuters use not one but two U-locks, and safeguard their wheels using cables or locking skewers. There are also companies that sell heavy chains, tracking devices and even a lock that sprays noxious fumes if it’s cut.

One person I met for this story moved all the furniture out of her bedroom except the bed so her bike could sleep behind the same door she does. Another locks up her bikes in her garage with a camera pointing at them, so she can look in on them when she wakes up worried.

9. ... But one that’s often overlooked is having pictures and the serial number.

If your bike is stolen, your chance of getting it back is much better if you’ve snapped a few pics — including one of the serial number, which is usually engraved near the pedals when you flip the bike over.

10. Bike rental kiosks aren’t just for tourists.

You might expect hardcore cyclists to sneer at the cruisers you can now check out from automated stations around the Bay Area. But more than one seasoned rider told me if they’re pedaling to a place where they wouldn’t feel great locking up their own bike, it’s worth it to just rent one instead.

Thank you to Robin Lee and Carolyn Thomas, who sent in the questions that prompted this episode. Thank you also to the many people who did not appear in the podcast, but who kindly made time to talk — among them Canaan Vallejos, Mailee Hung, Will Rose, Bryan Hance at Bike Index, Brian Wiedenmeier at SF Bicycle Coalition, and Eric Lonowski at Box Dog Bikes.