Don't leave your Trek bicycle in Portland's downtown on a Wednesday, without using a strong lock.

says that's the type of bike stolen most often in the city. The city's downtown is where most bikes are snatched, and Wednesday is the day most thefts in downtown are reported.

Bike thefts in Portland dropped slightly in 2012 from the year before, from 2,355 in 2011 to 2,050 – a 13 percent decrease.

Portland police released the study Tuesday to help encourage bicyclists to use U-locks to secure their bicycles, and to write down or memorize their bike serial numbers.

Only 34% of bike theft victims in 2012 knew their bike's serial number - making it harder for police to identify the bike recovered.

The top three neighborhoods where bikes were stolen: downtown, Northwest and the Pearl District – all locations lying within Central Precinct's domain. North Precinct recorded the next largest amount of bike thefts.

Not surprisingly, areas around Portland State University and Reed College were locations where a higher concentration of bikes were reported stolen.

Saturday was the most popular day of the week for thefts citywide. Wednesday, the most popular day of the week for bike thefts downtown.

Trek was the most stolen brand. Specialized, Schwinn and Cannondale came in next.

The value of bikes stolen ranged from $3,000 to $400; the highest number of bikes were in the $500 range.

Most stolen bikes reported having a cable lock that was broken and left behind at the scene; very few bikes using U-locks were reported stolen.

Police also have these tips to help prevent bike thefts:

Apartment dwellers should not leave their bikes in hallways or unlocked in the basement.

Either lock a bicycle with a U-lock in the basement or keep it inside your apartment.

Do not assume your secured business area is secure. Always lock your bike.

Consider double locking, especially in areas where bike theft is common.

Take a photo of your bike - if stolen, you can post the specific information and photo on http://bikeportland.org/stolenbikes.

BikePortland.org has teamed up with StolenBikeRegistry.com to help battle against bike thieves.

There are thousands of unclaimed bicycles in the Portland police property warehouse.

And officers don't routinely investigate bike thefts.

"It depends on how much follow-up can be done,'' said Sgt. Greg Stewart, of the bureau's crime analysis unit. "Individual officers may or may not investigate, depending on whether they have time or not.''

--Maxine Bernstein