The Power Meter Handbook: A User’s Guide for Cyclists and Triathletes

fixated on maintaining your “fitness,” even on easy days, then it’s best to put the computer in your pocket or put tape on it. Just ride easy on those days without having a number associated with it other than RPE.
    When you first start riding with a power meter, the handlebar readout can be captivating. There are lots of numbers, and they are constantly changing. It’s easy to lose your focus on the road and the cars around you owing to your concentration on the display. Because of this, for your first few workouts with a power meter, ride where the traffic is light and there are few intersections. Once you get the hang of the meter, you can get back to your usual routes. But always ride with your focus primarily on what’s going on around you rather than on what your power meter is displaying.
    Despite this appeal to set aside your power meter once in a while so that you can concentrate on how your body feels and responds as you train, I want to emphasize once more that using your new device for most of your time on the bike has the potential to make you fitter and faster than ever before. Once you have a solid understanding of the basics of the meter’s use, as I’ll describe in later chapters, your performance will be greatly enhanced. That’s the bottom line for why you should train with power. Now let’s move on to what power is.

2
What Is Power?
    I HOPE THAT CHAPTER 1 gave you a better understanding of why your power meter is such a valuable tool and why it is becoming so widely used by athletes in all bike-related sports. In this chapter I will explain what power is all about. I should warn you in advance that it will get a bit technical at times. But by the end of this chapter, you should be able to explain to your riding partners what your power meter is measuring and roughly how it does so. You should also be able to tell them how you’re using it to get fitter and faster.
THE BASICS OF POWER
    Let’s start this discussion with the most common term used in power: the watt. On a power meter, we call the numbers displayed on the handlebar computer “watts.” Watts indicate how much energy you’re expending duringthe ride and, as you’ll see below, how fast you’re expending it. We’ll come back to this relationship of power and energy in Chapter 6 .
    The unit of power is named after James Watt (1736–1819), a Scottish inventor and mechanical engineer. He was a genius who is credited with discovering in 1765 how to make the steam engine more powerful and efficient (exactly what we are after for your bike performance), thus making the Industrial Revolution of the late 18th and early 19th centuries possible. He also developed the concept of horsepower and formulated the fundamental mathematics for power measurement.
Power in Physics
    To help us get a broader understanding of power, let’s look at how physics describes it. After all, concepts about power arose in physics, and power— your individual power output, specifically—is the key to improving your cycling performance. Some of what follows may be a bit difficult to grasp on the first read, but hang in there with me as you think your way through this. In the end you’ll have a deeper appreciation for what’s going on when you ride your bike with a power meter. I’ll try to make my explanation as simple and painless as possible. Here we go.
    The watt is a measure of power determined by calculating the rate (think “time”) at which work is done. By “work” I don’t mean your job but rather the physical act of moving something, such as standing up while doing a squat exercise with a heavy barbell on your shoulders in the weight room. That’s work. Work doesn’t care whether you stand up on the squat fast or slow; you moved the weight from here to there, so the amount of work remains the same no matter how long you take to do it.
    Power itself is how much work you are doing and how fast you are doing it. The faster you stand up (shortening the time of the movement), the morepower you are producing on the squat. Physicists express this relationship of power, work, and time as a formula:
P = W/t
    This simply means power equals work divided by time.
    Let’s get a better understanding of work. Work is the result of an outside force (for example, your legs straightening while standing up during the squat) moving an object (the barbell) through a distance (from the low squat position to the fully standing position). So based on