This is an excerpt from Cycling Fast by Robert Panzera.
Training with a power meter is the current gold standard for measuring improvement in performance and setting standardized goals for workouts. A well-calibrated power meter provides an absolute measurement (in watts) of the power generated by the cyclist.
For comparison purposes, wattage is paired with body weight, normally taken in kilograms. For example, a 140-pound (64 kg) rider who produces 300 watts can be said to produce 4.69 watts per kilogram (W/kg; that is, 300 W divided by 64 kg). Similarly, a 170-pound (77 kg) rider who wants to achieve the same 4.69 watts per kilogram needs to produce 361 watts. Table 4.6 provides a list of the target wattage needed for each category of racing.
When you first start training and racing, owning a power meter may not be necessary. During the early stages of learning to race, you can perform workouts with a heart rate monitor and cadence sensor, or you can just ride by feel. These methods may be sufficient to help you show large gains in fitness. As time passes, gains in fitness may diminish without the use of outside methods for workout management, such as a power meter. Incremental improvements in cycling are known as “dialing it in.” Power meters are an excellent tool for helping athletes dial in their fitness as they mature in the sport. To see what a power meter looks like, refer to figure 4.3
Purchasing a power meter is an economic investment. You may find power meters that cost around US$400, but some may cost as much as US$2,500. Only a few companies develop power meters. Some power meters use the bottom bracket as the source for extrapolating power, others use the rear wheel hub to extrapolate power, while still others use wind velocity and rider drag to extrapolate power. Higher price does not necessarily mean a better power meter. Explore the available options by talking with other riders who own power meters, local bike shops, and your coach. This will help you find out which system works for you.
Power Training Zones
Knowing your sustained power (wattage) at a select time interval will give you guidelines for specific workouts. Standard time periods include 5 seconds, 1 minute, 5 minutes, and 20 minutes. Using a 20-minute sustained power test is the most common way to determine training zones. The five zones identified in table 4.7 will provide an effective platform for structured training.
The test described in this section will estimate your 20-minute sustained power (SP). Your 20-minute SP number may increase throughout the season as your fitness increases, or the way you achieve your 20-minute SP may change throughout the season (e.g., at 95 rpm instead of 85 rpm). Although not covered in this book, if you want to fine-tune your fitness, you can perform 5-second, 1-minute, and 5-minute SP tests. With this information, you can choose workouts that target and cover these time periods. For example, you can use sprint workouts to improve 5-second SP or intense on-the-bike strength workouts to improve 1-minute SP.
You must be fully rested before performing the 20-minute test. Make sure you read the instruction manual for your power meter to determine how to mark each interval; you can then review and record the data and wattages later. The best conditions for performing the test are on a flat road (or a road with a slight rise) with steady wind and limited traffic, traffic lights, and stop signs. A closed park road with few pedestrians is ideal. The test can also be performed on a stationary trainer (if the trainer provides even resistance throughout the duration of testing).
Before performing any maximum efforts, you need to be in good physical health as confirmed by a medical professional.
Test for 20-Minute Sustained Power
Warm-Up: 20 Minutes
Ride steady and easy in the warm-up with heart rates at less than 75 percent of maximum for 30 minutes. Near the end of the warm-up, perform one 5-minute (1 × 5 min) effort at 95 percent of what you estimate to be your time trial heart rate. Then perform active recovery—rolling at cadences between 70-85 rpm at <75 % of maximum heart rate (MHR)—for 5 minutes. (A discussion of MHR follows in the next section.) Next, perform three 1-minute (3 × 1 min) high-cadence (>100 rpm) efforts in the easiest gear. Perform active recovery for 1 minute between the 1-minute intervals. After the three 1-minute efforts are complete, perform active recovery for 4 minutes.
Actual Test: 20 Minutes
Mark interval and start a 20-minute all-out time trial effort with cadence at 85 to 95 rpm. For the first 3 minutes, ease into a time trial pace.
Record all test conditions, including the course, weather, wind, and temperature. Also record your diet for the day before and the morning of the test. During the test, you need to remain mentally focused. Pacing during testing is crucial—meaning building by increasing power throughout, as you would in intervals. Attempt to maintain the highest average watts for the test period.
Review your test using your power meter software. Label the test interval for the appropriate time period. The average wattage for the 20-minute time period is your SP for that time period.
Read more about Cycling Fast.