My one and only nasty road crash -- thorn in the front tire, tire rolled off the rim as rounding corner at 18 mph, bike and ride take opposite un-planned flight paths.

The sign of a true bicyclist? I'm sitting in the middle of the road with road rash all down my left side asking "is my bike OK?"

Moral of the story? In 20 years of riding, I replace the back tire and never swap. Wear a helmet (I can still remember the sound of the whack on the asphalt). Then, you get back on the bike and have fun.