Did you recently increase the amount of riding that you are doing? That is a standard cause of neck (and most other) pain. The only discomfort I experienced when I went back to riding a couple of years ago was neck pain, which resolved as support muscles developed over time. If pain is unrelated to increase in riding time, it may be as simple as increasing stack height in your stem. Most of the comments from others may be viable - even about the dreaded 'bent
. If you don't have any underlying problems, riding alone will strengthen your neck support muscles. I don't recommend separate weight/resistance work. Just ride more, shorter rides until adequate riding-specifec strength develops. The thing that gives me problems now are my hands. I'm in the process of getting some FSA K-Wing ergonomic handlebars for my Trek 2300 (Al frame, carbon fork). After I ride with them a while, I'll post a review. I'm sure I'm getting some twinges of arthritis, and I've got Dupuytren's contracture in my left pinky finger. Let us know if you are able to resolve your neck problem.