A teenager slaps a gas motor he buys online, or takes from an old lawn mower, onto his basic bike’s frame, roars the contraption to life and races down his neighborhood’s streets and sidewalks.

“We’ve started getting a lot of complaints about them,” said Mike Eeten, Pekin Police Department’s public information officer.

“They’re the bane of a cyclist’s existence” and dangerous to all around, including themselves, said bicycle enthusiast Tim Beeney of Peoria.

A businessman mixes a new hobby into his life by affixing a battery-powered motor kit onto his bike, donning a helmet and turning his daily commute into a law-abiding, 20-mph glide.

“We’re selling wheels all day long to those guys; they’re wearing them out,” said Michael Weis, manager of Little Ades Bicycle Shop in Pekin.

In both scenarios, motorized bikes are coming on strong in central Illinois.

“In the past couple of years we’ve definitely seen more of them,” Eeten said. “Usually not a day goes by that I don’t see one out and about.”

“We saw them start popping up about five years ago,” said Weis, whose shop will order electric motor bikes on request but doesn’t sell them from its floor.

The vehicles are not mopeds, which by state law requires a driver’s license to operate and can’t exceed 30 mph on city streets.

They are bikes purchased with motors attached, both battery- and gas-powered, or are adapted with kits bought online or ordered through stores such as Little Ades.

“They are legal on the street,” Eeten said. Their riders need not have a driver’s license, but must be at least 16 years old. Those bikes are limited to 20 mph – and to streets. Yet motor kits with speeds double that speed capacity are advertised online.

“We’ve been issuing speeding tickets,” to riders exceeding the limit, Eeten said. Police also have taken more calls complaining of motorized bikers on sidewalks, and of the noise caused by bikes “with weed-whacker engines,” he said.

As the prototypes of motorcycles, gas-motorized bikes go back more than a century. Kits are available to turn a simple peddle bike into a virtual motorcycle that teens “don’t have a clue how to operate” safely, and who often don’t obey basic rules of the road, said Beeney, a co-founder of Bike Peoria Co-Op.

Battery-powered, or E-bikes, are another matter, he said. “I generally don’t have a problem with them,” in good part because they cost more and tend to be owned by adults with experience on the roads and respect for the rules governing them.

E-bikes “are starting to grow, but they’re not as common” as gas-powered models, Weis said.

The former, he said, typically require some pedaling from their rider. They appeal more to “older people and those who don’t have a (driver’s) license or don’t want to drive” on their short commutes to work. “A lot of them have taken (E-bikes) up as a hobby.”

Jimmy King turnedlast spring to a battery bike that he bought from a friend for his daily eight-block commute to his bartending job at a Peoria Heights restaurant/tavern. He has no plans for now, he said, to buy another car.

“Fifteen miles (an hour) is fast enough for me,” King, 55, said. He sticks to side streets, but a month ago took a tumble when a vehicle passed close to him from behind.

“Our biggest concern is safety” of the riders and those they encounter on their rides, Weis said.

“It’s a really torn subject” in his business, he said. “Most (riders) are responsible, but there’s always those few who ruin it for everyone else.”

Follow Michael Smothers at Twitter.com/msmotherspekin