Understanding the Metrics on Bikes

Making Sense of Your Power Meter on the Bike

Power meters have revolutionized cycling. Unlike heart rate, which can be affected by things like fatigue or heat, power meters give you real-time data on how hard you're actually working. But if you’ve ever stared at your screen mid-ride wondering what all those numbers mean—FTP, watts, NP, TSS—you’re not alone.

Here’s a simple guide to understanding the key power metrics and how to use them to improve your cycling performance.

1. Watts – Your Output
Watts are the raw measure of how much power you’re generating. Think of it like the horsepower of your legs. The higher your watts, the more power you’re pushing into the pedals. But watts on their own aren’t the full story—you need context.

2. Watts per Kilogram (W/kg)
This metric takes your weight into account and is especially useful when comparing fitness or racing on hills. Two cyclists pushing 200 watts aren’t equal if one weighs 60kg and the other 90kg. The lighter cyclist has a higher W/kg and will likely climb faster.

3. Functional Threshold Power (FTP)
This is the gold standard for cyclists. FTP is the maximum power you can sustain for about an hour. Knowing your FTP allows you to train in specific power zones, much like heart rate zones. You can calculate your FTP through a dedicated test (often 20 minutes) or via software like Zwift or Training Peaks.

4. Normalized Power (NP)
NP gives a more accurate picture of the true difficulty of a ride. Unlike average power, which can be skewed by coasting or recovery, NP accounts for surges and variability—especially helpful for interval training or hilly rides.

5. Intensity Factor (IF)
IF is the ratio of your ride’s Normalized Power to your FTP. An IF of 1.0 means you rode at your threshold. Most endurance rides fall around 0.6–0.8, while high-intensity intervals may hit or exceed 1.0. It’s a great tool to gauge the intensity of your session.

6. Training Stress Score (TSS)
TSS quantifies the overall load of your ride, taking into account duration and intensity. It helps track fatigue and manage your training over time. Higher TSS = more training stress. Too many high-TSS days in a row? Time for a recovery ride.

7. Don’t Get Lost in the Data
While power data can be incredibly useful, it’s easy to fall into the trap of obsessing over every number. Use these metrics to guide your training, but don’t forget to enjoy the ride. Some of the best training days are the ones when you ride by feel, not just by numbers.

In Summary
Your power meter is a tool—not the goal. Understand what the key metrics mean, use them to shape your sessions, and watch your fitness soar.

But remember: numbers matter, you matter more.