SOUTH BEND – Bicycle thieves, roused from long winter slumbers, are on the prowl in the city, snatching up unsecured dirt bikes, mountain bikes and ten-speeds in increasing numbers, police say.

Since May 1, according to data provided by South Bend police, 17 bikes have been reported stolen in the city, compared with only three the previous four months.

And those numbers likely understate the problem, South Bend police spokesman Capt. Phil Trent said, since many bike thefts go unreported.

John Lymburner woke Tuesday to find his wife’s bike missing from beside their garage in the 500 block of West Indiana Avenue, where it had been sitting unsecured.

The 59-year-old was not surprised.

“This isn’t the first time.” he said, “Last year her bike was stolen, too.”

Lymburner said the bike was left unchained because it was old and because it would not fit in the garage, where their children’s bikes are stored.

According to Trent, most of the bikes reported stolen in the city are unsecured or improperly secured, making them easy targets for would-be thieves and joy-riders.

To prevent thefts, Trent recommends people secure their bikes with some sort of lock, preferably to a fixed object, such as a bike rack or lamp post. If possible, he said, store bikes indoors.

Also, the bicycle’s serial number should be recorded, he said, so that it can be identified and returned upon recovery.

“We can’t help you if you don’t have the serial number,” Trent said.

Finally, take a look around, he said. Most stolen bikes are quickly abandoned, he said, and might be nearby.

“A lot of bicycles are taken,” Trent said, “and a lot are self-recovered.”