Bike was stolen from sidewalk in front of apartment. I heard the lock get cut, ran outside and chased the person. I caught sight of the person riding the bike two blocks south and saw them turn onto Paulina and then Milwaukee going northwest before I lost sight. When i got back to where it was stolen, I noticed that the person had left the bolt cutters used to cut the lock on the sidewalk. I filed the police report over the phone, and then got into a car and headed to look for the bike. In the car, I caught sight of the person going north on Wood (two blocks west of where it was stolen). This was about 15 minutes after the bike was stolen. I called 911 while following the person and told the operator where the person was heading. The person was chased onto North ave., then north on Hermitage, east on Bloomingdale and then north on an alley parallel to Hermitage before the person was out of sight. At that point I was off the phone with the operator and was told to wait in that area for an officer to show up. I talked to two different officers at that intersection before heading back. They said they would keep a look out for the bike.