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

gallon. The more miles you cango on a gallon of gas, the more economical the car is. When you ride your bike, you also have an economy rating, only now it’s meters per milliliter of oxygen. The less oxygen it takes for you to turn the pedals at any given submaximal power wattage, the more economical you are. The longer the race is, the more critical economy becomes.
    For a triathlete doing an Ironman, economy is a huge determiner of performance. For a road cyclist racing a 45-minute criterium, economy is still important but not nearly as critical to the outcome. The reason for this is that the Ironman bike ride is done at a significantly lower power output than a 45-minute criterium. The crit is raced at an intensity between AT and VO 2 max.
    So these fitness markers are critical to such a performance. The Ironman is raced at around 70 percent of AT. During such long durations, the rider can’t afford to waste energy, as the gut has a limit as to how much energy it can process from food and drink while racing. If the rate at which energy is expended owing to low economy is greater than the intake rate, the athlete will “hit the wall.” The crit racer can afford to waste some energy because the race outcome will not be decided by how much energy is wasted; there is plenty of stored fuel available for such a short race, and none will need to be replaced before the race ends.
    When you are riding a bike, your economy is likely between 20 and 25 percent effective, meaning that 75 to 80 percent of all the calories you burn are not producing power. Most of that lost energy is expended as radiated heat. That may seem like a lot of lost energy, but it’s common. Interestingly, research reveals that athletes with high aerobic capacities tend to be somewhat less economical than athletes of otherwise similar ability with lower aerobic capacities.
    Economy is dependent on many factors, several of which are outside your control, such as the length of your thighbone (long femurs relativeto leg length pedal more economically than short ones) and your ratio of slow-twitch to fast-twitch muscles (slow twitch are more economical). These largely result from who your parents were.
    The most significant aspect of economy over which you do have control is how you pedal. “Mashers” (riders who push big gears at low RPM) are less economical than “spinners” (riders who spin the pedals at high RPM), How rapidly you apply torque to the pedals has a significant effect on performance. With your power meter, you’ll be able to determine the cadence range at which you are most economical. This is critical information for your performance.
     
    THE BOTTOM LINE is that you’ve made the right decision to purchase a power meter. It is the one instrument you can buy that shows your power level and then helps you monitor your improvement in power as your training progresses. In other words, it is the best possible way to monitor and focus your training efforts. You’ll be not only a more savvy rider because of it but also one who is fitter and faster than you’ve ever been before—if you know how to use it. That’s where we will be going next.

3
Getting Started with Your Power Meter
    THE PURPOSE OF THIS CHAPTER is to help you become acquainted with your power meter so that you can start using it effectively. Of course, your power meter isn’t magic. You don’t just mount it on your bike and all of a sudden you’re training differently and become an overnight podium contender. The power meter doesn’t work that way. As with any tool, you’ll have to undertake some adjustment and learning to make the best use it. And there’s a lot of adjusting and learning to do. Power meters are rather complex devices. You’ve probably started to get that sense from having read the first two chapters. And so far we’ve only scratched the surface.
    While power meters are new as mobile devices for our bikes, they have been used as big, cumbersome clunkers in exercise physiology labs for decades. Sport scientists have used them to study performance and almost everything imaginable related to aerobic capacity, anaerobic threshold, andeconomy. Essentially, what you have on your bike is a powerful scientific tool. There’s no doubt that it can help you become a much better rider, but you’ve first got to figure out how to use it.
WHAT’S ON YOUR HANDLEBARS?
    Before you get serious about doing power-based workouts, I suggest you take 7 to 10