This step is crucial to avoid injury and to improve cycling performance. A warm up enhances your speed and power by increasing blood flow and muscle temperature. A warm up is necessary for your heart as well as your legs. This can be prevented by starting out slowly. You're adequately warmed up and ready to shift into high gear once you've broken a sweat.
Good flexibility is important and can reduce the likelihood of injuries.
The best time to stretch is after exercise, when your muscles are warm. If it's not convenient to stretch in a parking lot after a ride, stretch when you get home. Try to relax and breathe deeply. If you aren't sure what specific stretches to do, pick up a book or video, or talk with a staff person at your health club. If not, skip this section.