A "wobble," or a sudden shaking of the front wheel and handle bars, can usually be traced to:

A “wobble” is when the front wheel and handlebars suddenly start to shake from side to side. Most wobbles are a result of improper loading, unsuitable accessories, or incorrect tire pressure.

• Incorrect tire pressure or uneven loading.
• Improperly tightening the front wheel to the frame.
• Hitting an object with the front tire.