Do the One-Legged Drill
There are a number of drills that you can do to build your cycling endurance. Professional triathlon coaches like Joe Friel use many of these drills. These should be in addition to your rides, which should increase in speed and distance as you become more fit. Do this first drill on an indoor trainer. Unclip one of your feet from the bike pedal and place it on the floor. Put the bike in a low gear and pedal with your other foot. At the top of the pedal stroke, there is a dead spot that is difficult to pedal through. Focus on this spot as you pedal. When your leg gets tired--which probably won't take long at first--change legs. If you do this exercise regularly, you will see your endurance improve.
Build Endurance With the Shoe Top Drill
While you are pedaling, press your foot against the top of your shoe and avoid the back of your shoe. This exercise helps to train your muscles, which is especially important during transitions on the bike. These transitions occur when you move from flat ground to hills or encounter another change on your path.
Do the 9-to-3 Drill Anytime
You can do this exercise on a regular bike or an indoor trainer. Think of the wheels of the bike as the face of a clock, and put your forward foot at the 3 o'clock position and your back foot at the 9 o'clock position. Quickly move your forward foot to 9 o'clock and your back foot to 3 o'clock--skimming over the other points of the clock without stopping.
Try the Toe-Touch Drill
The toe touch drill also looks at the bike wheel as the face of a clock. When your foot is almost at the 12 o'clock position, try to touch your toes to the front end of your shoe. Your heel should be slightly higher than the ball of your foot when you do this.
Move Beyond Your Comfort Zone
Cadence is a term that refers to the number of pedal strokes one of your feet completes in one minute. Everyone has a comfortable cadence level, and the point of this drill is to increase it. You can tell what your comfortable cadence range is because when you fall below it, you will feel as though you are using too much muscle to push down, and when you are going too fast you will begin breathing too quickly. For this drill, gradually increase your cadence for 20 to 30 seconds until you start bouncing in your seat. Then go back to your usual speed for 30 seconds. Keep repeating and you will increase your cadence, which will increase your cycling speed.