The bottom line is that it never was an ideal city bike. The streets of NYC are horrible, not much can last forever. But to give you better odds...look at what NYC bike messengers ride. While some nuts ride single speed fixed gear bikes with no brakes, most use fairly light aluminum framed hard tail mountain bikes with front suspension, and non-knobby tires. Many add a suspension seatpost. Actually the Citibikes are pretty nice to ride; much lighter than they look. But a key feature of the Citibike is the fairly broad tires that help absorb the bumps, along with a robust aluminum frame. But a nice hardtail can be quite a bit lighter than a Citibike, and give you some suspension to deal with the bumps, and more gears as well. Time to look for something new.