Since you asked about my technique, I probably ought to add that I shoot from trackside most of the time. If you're shooting from the stands, fill flash is not very useful. It is probably better to go down track an pan the shots. It isn't so much the fact that the bikes are going fast as it is the rate of change (acceleration) from the starting line. The farther down track you go, the less rate of change you encounter. You have to find a happy medium where acceleration is reasonable and speed is not so high that you can't keep up. If you are constrained by sitting in the bleachers and the light is starting to go away, then down track panning is the way to go. Even that will take some practice, but if you do it enough, you'll get the hang of it.