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

up with your FTP, but I’ve found it to be remarkably close for many riders. This is an estimation based primarily on body weight and other personal factors. It involves some math, so you’re likely to need a calculator. There are five steps in estimating your FTP this way, some of which may not apply to you.
    Step 1. Double your body weight in pounds. This is your base number. Example: A body weight of 150 pounds means a base of 300 (150 × 2 = 300).
    Step 2. If you are a woman, subtract 10 percent from the base number found in step 1. Example: A 120-pound woman’s base is 216 (120 × 2 = 240; 240 – 24 = 216).
    Step 3. Subtract from your base number half a percentage point (0.5 percent) for every year beyond age 35. Example: If the 150-pound rider in step 1 is 50 years old, he would subtract 7.5 percent from 300 (50 – 35 = 15;15 × 0.005 = 0.075). This would modify the base number to 277 (300 × 0.075 = 22.5; 300 – 22.5 = 277.5).
    Step 4. If you live at about 5,000 feet altitude, subtract an additional 5 percent. For every additional 1,000 feet of altitude above 5,000, subtract another 1 percent. Example: For a 35-year-old rider with a base of 277 who lives at an altitude of about 5,000 feet, the adjusted base would be 263 (277 × 0.05 = 13.85; 277 – 13.85 = 263.15). If you are in the first month of adapting to a higher altitude, then double the percentage subtracted. Note that short visits to high altitude require an adjustment of your FTP.
    Step 5. If you ride your bike fewer than six times a week, you will need to make one more adjustment. This is likely to affect triathletes more than road cyclists or mountain bikers. The less frequently you ride, the lower your FTP is likely to be. So if you typically ride five times a week, subtract 2 percent. If you ride four times weekly, subtract 4 percent. If you usually ride three times in a week, subtract 7 percent. For two rides weekly, subtract 10 percent. Example: A rider with a base of 277 who rides three times each week would have an adjusted base of 258 (277 × 0.07 = 19.39; 277 – 19.39 = 257.61).
    Your final number is an estimation of your FTP. Remember, though, that it could be well off the mark. It’s a rough estimate at best, particularly because there are variables besides body weight, gender, age, altitude, and training frequency that could also affect your FTP. For example, the type of weight you have would influence your estimated FTP. Excess fat or muscle, especially upper-body muscle, will skew the results. If you have a considerable amount of either of these, then your estimated FTP fromthe above steps is likely too high. Knowing lean body mass from body composition measurement is a better predictor if fat is an issue. That won’t help overly muscular riders, however. Then there is also the weight of your bike. This is not included in the steps above, but it certainly is an issue. A heavy bike will lower an otherwise high FTP just as excess body weight does. Bike weight is especially significant for a small woman. An 18-pound bike is a heavy load to carry uphill for a 100-pound rider. In short, I wouldn’t suggest relying on estimation beyond just getting started. At the first opportunity, use a more accurate measure from the above possibilities.
Keeping FTP Current
    Over the course of the season, you may do some mix of the above methods for estimating FTP. You are likely to use all of them, some more than others. The one I use the most for the athletes I work with is the 30-minute test. What’s most important is that you keep your FTP current. Check it at least every 6 weeks and preferably more frequently. It’s a good idea to schedule testing or racing in your annual training plan with this in mind. Testing should be done after a few days of rest.
    You could also simply pay close attention to changes in how hard a given power output feels in workouts and races. You may find, for example, that after three or four weeks of repeating a given workout, the effort seems easier. This is a good sign that your FTP has increased—along with your fitness—so this is the time to measure it.
    FTP is the most easily measured and accurate way of determining changes in fitness. Your most important training objective during the season is to raise your FTP to as high a level as possible. Why? Let’s look at it this way: If your closest competitor has exactly the same VO 2 max as you,the rider who prevails on race day will be the one with the higher