You can start by describing the bike in specific terms. That way, we're already knowing what to look for. Start with the brand name on the frame and the type of bicycle. Then post the manufacturer and model of the drivetrain components. Then describe what is happening with the derailleur. Before you know it, you'll have reached your 10 posts. Also, in your profile, list your geographical area (e.g., greater Columbus, OH area). That way, someone in your area can point you to local resources as needed.