Hi Pavel.
I feel sorry for you, and wish that you'll find your bike soon.
First of all go to the police station in ramat gan and file a report for stolen bike ( I hope you have a record of your bike serial number).
Most stolen bikes find their way to the old central bus station in Tel Aviv (neve shanan street) and sold buy illegal immigrants, this is highly risky to confront them, so be advised.
Good luck.
חיים פעם אחת, צריך לנצל כל רגע.