CHICAGO (WLS) -- A Lincoln Park bike shop owner, who has been in business on Chicago's North Side for the last 40 years, said he may have to close after $20,000 in merchandise was stolen early Tuesday.Mark Mattei opened Cycle Smithy in 1978. This is the second time this month that burglars have targeted his store, which is located in the 2400-block of North Clark Street."I'm not sure I can continue on as a business this way," Mattei said.Mattei said he can't believe it has happened again."This is the second time I've been broken into. Other shops have been broken into three times," he said.Witnesses told police four people broke through the glass of the front door just before 4:30 a.m. Mattei said they took more than $20,000 in high-end bikes and equipment. Witnesses said the thieves fled in two vehicles southbound on Lake Shore Drive."Between the first and second time, I put security bars in front of my shop. But they cut through all the locks. They came to the second floor here, my showroom, and cut more locks on the high-end bikes here in the showroom," Mattei said.Robbers previously struck Cycle Smithy on Jan. 27. Mattei said they got away with thousands of dollars in merchandise that time, too.Well-Fit Performance was also struck in this latest rash of robberies. Video surveillance footage shows thieves smashing through windows and ripping off customer bikes stored at the shop, worth about $20,000. This is the third time since December that they've been hit up. A total of about $70,000 in merchandise has been stolen in all of those burglaries, according to Well-Fit Performance owner Sharone Aharon."We thought we had a solution," he said. "They're very determined. I believe they know what they're doing."Gene Bruber, manager of bike shop Johnny Sprockets, said the stores have been in touch with each other."We are sharing information as best we can and tips as to how to best protect ourselves," he said.While some business owners blame a lack of police presence for the crimes, Maureen Martino, executive director of the Lakeview East Chamber of Commerce, says business owners and neighborhood residents must play their part to help stop this rash of crime."The chamber and the SSAs have augmented that with private securities, but it's seasonal. So everybody's got to come to the table and be part of helping the neighborhood stay safe," she said.No one is in custody.