Why Your Indoor Power Sucks (And Why That’s Normal)
Almost every cyclist notices it eventually: The power numbers indoors just don’t feel the same.
Intervals that feel manageable outside suddenly feel brutal on the trainer. FTP numbers drop. Threshold efforts feel harder. Motivation disappears faster.
And many athletes immediately assume:
“I lost fitness.”
Usually, that’s not the problem.
Research consistently shows that cyclists often produce lower sustained and maximal power indoors compared to outdoors — even when fitness stays exactly the same.
So if your indoor power “sucks,” you’re probably more normal than you think.
What the Research Shows
Multiple studies have compared indoor and outdoor cycling power, and a consistent pattern emerges: maximal and sustained power outputs tend to be higher when measured outdoors compared with indoors.
In elite cyclists, Lipski et al. (2022) found that maximum power metrics (including critical power) were significantly higher in outdoor tests than indoor ones, with outdoor power about 4–8% higher on average.
That means if you base your zones on an outdoor FTP or test and then ride indoors without adjustment, your indoor workouts can feel noticeably harder than intended — not because your fitness changed, but because the environment did.
👉 Note: The exact difference between indoor vs outdoor power output varies a lot between individuals and isn’t a fixed % across all athletes.
Why Outdoors Can Yield Higher Power
Here are a few scientific reasons:
Biomechanical differences: Outside, riders naturally vary cadence and body position and can briefly stand or shift weight, which can aid force application. Indoors, your body and position are more constrained.
Cooling & hydration: Indoor airflow is limited, leading to greater heat strain — and heat strain reduces sustainable power.
Psychological factors: Outdoor scenery, shifting terrain, and tactical elements often reduce perceived exertion and boost performance.
Interestingly, some research also shows indoor/outdoor FTP might not differ statistically for some riders, but individual variability is high, which means we should personalize, not assume identical zones.
What This Means for Your Power Zones
Power zones are typically built around your FTP or threshold power. But if your indoor FTP estimate is based on outdoor data (or vice versa) you can run into training mismatches.
Here’s how to adjust your approach:
1) Test in the environment where you train most.
If most of your structured efforts are indoors in winter, do an indoor FTP or threshold test on the trainer. Likewise, do outdoor tests if you’re primarily riding outside.
2) Expect a small indoor down-shift for power zones.
Rather than a flat 10% rule, use your own data: compare recent indoor and outdoor max efforts to see the difference in your power profiles, then adjust zones accordingly.
3) Consider perceived effort + heart rate, not power alone indoors.
Environmental factors like heat and motivation can make indoor power feel harder than outdoor power at equivalent wattages — smart pacing matters.
4) Understand variability isn’t just measurement error.
Different power meters and trainers can vary ±2–5% — so consistency in testing devices helps tighten your zone estimates.
PRO TIP: After 8–12 weeks of training regularly indoors you might see the gap narrow as you adapt to indoor conditions.
The Bottom Line
Indoor and outdoor power are not always interchangeable. Controlled scientific tests show riders typically produce slightly higher power outdoors than indoors, especially during maximal efforts, which will impact how your zones feel and how you should set them.
That doesn’t make one “better” than the other.
It just means you need context-specific zones for your best training results!