Power. It’s what we’re all after.
As power meters become more affordable and appear as standard equipment on more bikes, more riders are wondering what to do with this newfound data. FTP, W/kg, NP, neuromuscular power—there are a million new things to learn, so let’s start at the beginning.
What does a power meter actually measure?
Power meters measure how quickly you’re doing mechanical work, typically by combining torque with rotational speed. Common systems measure power at the pedals, crank arms, crank spider, or rear hub. Smart trainers can also measure or estimate power indoors.
They all have their own quirks and considerations, but for this conversation, the important thing is that the power meter you test with should ideally be the one you use in training. This helps keep your readings consistent. A direct-drive trainer and power meter pedals may report different numbers because they measure at different points in the drivetrain, and because of differences in calibration and accuracy.
Your power output is measured in watts—the same unit used to describe how much electrical power a lightbulb consumes. When your bike computer displays power in real time, that number can fluctuate by hundreds of watts over a few seconds because of changes in terrain, coasting, sudden acceleration away from a stop sign, or any number of other variables. Finding the data screen that works for you takes a bit of trial and error. If the constantly bouncing number seems like too much, we recommend using a 3-second or 10-second average to smooth it out.
What’s this FTP thing people keep talking about?
FTP, or functional threshold power, was developed by exercise physiologist Dr. Andrew Coggan and popularized through his work with coach Hunter Allen. In simple terms, it’s the highest power you can sustain at a roughly steady effort for approximately an hour. The exact duration varies from rider to rider.
Common ways to estimate FTP include a 20-minute test and a ramp test. You can also assess it through a longer, sustained effort. Different tests suit different riders, and your training background and individual physiology can affect the results. Like finding your preferred data screen, this can take some trial and error. Use a consistent testing method, then check that the resulting training targets are appropriate for you.
Once you’ve found your current FTP, you have a starting point for setting your power zones. For those familiar with heart rate training, this is where power training goes its own way. Depending on the system or coach you’re using, you may see anywhere from three to nine zones, each describing a different range of effort.
Power zones are set independently of heart rate, and what feels easy at the beginning of a ride can feel exhausting toward the end. Power gives you a direct target for your effort, while heart rate and perceived exertion help you judge how your body is responding. Training at different intensities and durations develops your energy systems and helps you adapt to the demands of a given output.
Over time, consistent training and adequate recovery can help you become stronger and more aerobically fit, potentially raising your FTP.
I’m not racing, why do I care?
Many of us aren’t riding to throw down at a crit or suffer through Leadville. Knowing your FTP can still help you manage your effort on a long ride and track your progress over time.
For example, a rider with a 250-watt FTP heading out for a few hours might aim for around 65–75% of FTP early in the ride (roughly 163–188 watts) as a starting point for a manageable endurance effort. The right target will depend on fitness, ride duration, terrain, and fueling.
Repeated or prolonged efforts above FTP can add fatigue and leave you with less energy later in the ride. Just like a professional managing their effort for the last climb, you can pace yourself to reach the base feeling strong and snappy.
If you have the tools to measure and monitor power, they can help you enjoy longer days in the saddle which is what many of us are looking for in the first place.