Know Your Zones
A recent long ride tested my resilience due to tech glitches. Low batteries in my stationary bike’s pedal power meters disrupted ERG mode, pushing power outputs beyond my prescribed workout. As a beginner, this might have derailed me, but years of training helped me rely on my “feel” for power and heart rate zones to salvage the session. Here’s how to develop that instinct to handle tech failures during training.
I use the Stages SB20 for indoor Zwift rides, a cost-effective setup compared to Wahoo or TacX indoor bikes. It mirrors my road bike’s fit, with adjustable gearing, pedal power meters, a central control power meter for ERG mode, and aero bars. Saturday’s workout, a two-hour hilly 70.3 course simulation, included longer intervals of Z4 power with Z2 recovery in between. Having done this ride multiple times, I know the effort each segment demands.
About 45 minutes in, after the first Z4 interval, I felt off. My heart rate spiked, my cadence dropped almost 10 RPM below normal, and fatigue was higher than expected. During the Z2 recovery, my heart rate stayed at 142 BPM instead of the usual 130, indicating the effort was higher than it should have been. My legs felt strained, my cadence kept slipping, and heart rate was out of the reasonable range.
Suspecting an issue, I checked the Stages app and found the pedal power meters’ batteries at 5%. Low batteries cause ERG mode to struggle, failing to adjust power accurately during the ride. The 160-watt Z2 felt closer to 200 watts, based on my heart rate being what it typically is for 200 watts. Early in my training career I might have quit. Instead, I was able to rely on my familiarity with my zones and complete the workout.
Developing the Feel for Your Zones
Learning your power and heart rate zones takes time and attention. Apps like TrainingPeaks display your heart rate and power charts, but “feeling” your zones means understanding how they align. For example, at the top of my Z2 power (185 watts), my heart rate rarely exceeds 135 BPM during extended efforts. This can help me estimate my power on outdoor rides where I don’t have a power meter. It won’t be perfect, but it’s close enough for the purpose of estimating zones.
On Saturday, my heart rate sat at 142 BPM during Z2 segments, signaling trouble. From experience, I know 142 BPM corresponds to 205-215 watts, not the prescribed 160 watts. This gap confirmed the tech issue. Here’s some tips for building this awareness:
Track Heart Rate and Power: During Zwift rides, note your heart rate at specific power outputs. For instance, observe how your heart rate stabilizes at the top and bottom ends of Z2 power.
Monitor Leg Sensation: Pay attention to how your legs feel at different power levels. How do they feel at Z2 power? How does a higher or lower cadence affect your legs? How long can you typically hold that power feeling easy? These are all simple metrics to notice during your rides that will help you feel your zones.
Observe Cadence: Cadence affects effort perception. Different cadence at the same power output will affect your heart rate. It’s helpful to get familiar with your heart rate ranges at a high and low cadence.
Identify Patterns: Over time, consistent patterns emerge despite daily variations. My Z2 rides reliably show a heart rate below 135 BPM at 185 watts, giving me a baseline. At high power outputs observe what causes the effort to feel difficult, and practice manipulating different variables to sustain the hard effort.
This awareness is critical when tech fails. On Saturday, recognizing my heart rate was too high for Z2 power let me adjust my effort mentally, and push through the rest of the workout. Beginners might not notice these cues, risking overexertion or quitting.
You may be asking, why push through if the effort was higher than prescribed? Why not check down to an easier ride?
Two reasons.
One, I was out of replacement batteries.
Two, I look at every training session as an opportunity to practice something. For this session, it was a lesson in pushing through when the ride was harder than it should’ve been. This happens in races all the time, so why not sharpen that mental edge in training when given the chance.
The Takeaway
Tech issues, like low batteries, are inevitable, but they don’t have to ruin your training. By learning the relationship between heart rate, power, and physical feel, you can navigate disruptions more easily. Pay attention during “boring” rides. Those Zwift sessions are perfect for developing this skill. Track your heart rate, feel your legs, and monitor cadence across power zones. Over time, you’ll develop an instinct that keeps you resilient in training, tech or no tech.