"A concussion is like an iceberg," said Dr. Anna Abramson of Mill Valley. "You only see the tip and you don't see the most serious part. Most people don't know they have it and don't seek medical attention if they do. I don't think people have a good idea of the ramifications of having a serious crash."
Dr. Abramson, an attending physician and assistant clinical professor at the University of California, San Francisco, is also an avid cyclist. She says bike riding can be even more dangerous than car racing. "Cycling is basically the same as NASCAR, but instead of having a protective cage around us, we just wear Lycra and a helmet."