A common defense to any bicycle accident is that the rider caused the  accident. Common causes of bicycle accidents which may be attributed to cyclists are:

Failure to Abide by the Rules of the Road
Bicyclists are held to the same degree of care as motorists, and must be familiar with appropriate state motor vehicle code regulations.

Careless Conduct
Cutting in front of cars, unsafe lane changes, excessive speed, or other reckless maneuvers may be a contributing factor in an accident.

Inattentiveness to Road Conditions
Cracks, bumps, contaminates, water, traffic, etc. can make riding hazardous. It is up to the cyclist to be alert for any condition that may lead to an accident.

Improper Assembly or Bike Maintenance
Many cyclists prefer to perform their own assembly or maintenance. Factors leading to accidents may be improper tire/tube installation or pressures, loose parts, obvious fatigue cracks, wear and tear, etc. It is up to the rider to make certain before every ride that the bike is in good condition, components properly installed, and all is in order according to the manufacturer’s specifications and recommendations.

Failure to Wear a Helmet
Even if an accident is caused by some of the factors which will be discussed hereafter, failure to wear a helmet will always be an affirmative defense if a head injury is involved.