What are some common causes of a wobbly bike and how can it be fixed?

Common causes of a wobbly bike include loose or improperly adjusted handlebars, wheels out of alignment, loose or worn out bearings, or an unbalanced load. To fix a wobbly bike, check and tighten all bolts and screws, adjust the handlebars and wheels to be straight, replace any worn out bearings, and evenly distribute the weight on the bike.