Have you ever had an accident on a bike? Riding a bike can put the rider in a uniquely vulnerable position, especially in heavy traffic. Even today, many motorists do not respect cyclists’ rights on the road; some are even directly hostile. I had my own run in with a car at the age of fifteen.
As I did regularly during high school, I was riding back home. It was hot September day in Orange County; the air was still and there was no relief from the Santa Ana winds. I was riding shirtless, my skin bronzed from the sun. As I sped downhill on the 5 Freeway Overpass, usually my favorite part of the trip, a sedan meandered in front of me as it moved to the far right lane. I didn’t have time to swerve or brake. Luckily, the car didn’t hit me, but it forced me onto an exit ramp that was a sharp curve. I was going way too fast to make the turn. My bike hit the curb and my body flew over the handlebars. Bystanders later told me that my flying body almost hit a nearby stop sign. Instead, I fell onto my shoulders and rolled, the hot asphalt stinging my bare back. Amazingly, I was still conscious, although the wind had been knocked out of me.
About ten minutes after impact, I heard a siren. It took a few minutes to register: “Oh yeah, that siren is for me!” 
The paramedics strapped a neck brace on me and sped to the nearest hospital in Fullerton. An ER doctor made the diagnosis – a compression fracture on one of my vertebrae. To this day, I have a black ink mark on my back where the doctor made that determination. I was in a back brace for six weeks, and obviously could not ride a bike during that time. The city bus became my ride to and from school for the duration, but I couldn’t wait to get back on a bicycle again!
VECTr - Variably Expanding Chain Transmission 