Tick sound while pedaling
Ok this is after I tried my best to adjust the derailleurs' limit screws... (things seem fine for the most part after several rides, with very rare rubbing).
Occasionally, when I was pedaling, I hear a no-so-loud tick sound, very similar to the sound we normally hear when cruising the bike (i.e. wiithout pedaling), but less loud than that. When this happens, it's only every 1 or 2 cycles of pedaling, not constantly. It's not rubbing sound, just ticking like cruising sound (not as robust). What could be the cause? How serious is the problem?