Guides
Understanding Power Smoothing in Training Apps
The short answer
- Power smoothing averages your watts over a few seconds so the on-screen number stops jumping. It changes the display only, not the data saved to your .fit file.
- It makes your power look steadier and slightly higher in the moment, which flatters pacing but hides how spiky your pedalling really is.
- For honest training and accurate intervals, turn smoothing off. Wahoo trainers smooth aggressively by default; you switch it off in the Wahoo app.
- Your saved file and your power curve use raw 1-second data regardless of the smoothing setting, so your FTP and TrainerRoad analysis are not affected.
- Smoothing is fine for steady endurance rides where a calmer number helps you hold a zone. Switch it off for short intervals and any accuracy testing.
Power smoothing is why your watts look rock steady on a Wahoo turbo but jump around on a power meter. Power smoothing averages your power over a short window, usually around 3 seconds, so the on-screen number stops flickering and looks calm and controlled. It only changes what you see in the moment: the raw data saved to your file is untouched. That is why it flatters your pacing without actually changing your FTP or training load.
The first question I get when a rider sees that suspiciously flat turbo number is whether the trainer is lying to them. This guide explains what smoothing really does, why it exists, and exactly when you should switch it off.
What is power smoothing?
Power smoothing is a rolling average applied to your power figure before it reaches your eyes. Instead of showing the genuine watts at each instant, the trainer or app displays the mean of the last few seconds. The most common window is 3 seconds, which is enough to hide the natural rise and fall of a single pedal stroke while still reacting quickly when you change effort.
The key thing to understand is where the averaging happens. There are two different versions and people constantly muddle them:
- App-side averaging (for example a “3s power” data field in Zwift or your Garmin). Your app receives the raw watts and chooses to display a smoothed number. The real figure is still in the file.
- Hardware smoothing (Wahoo’s Power Smoothing, some Elite firmware). The trainer smooths the broadcast itself, so every app you connect sees the already-smoothed number on screen. Crucially, even here the recorded .fit file still gets the raw samples.
Why does power smoothing flatter your numbers?
When you pedal, power is not constant. It peaks twice per revolution, once for each leg’s downstroke, and dips through the dead spots at the top and bottom. On a real power meter at 200 W you might see the number swinging between roughly 150 and 260 W several times a second. That is normal and healthy.
Smoothing erases that swing. Two things follow. First, the number looks far steadier than your legs actually are, which feels reassuring but hides a choppy, inefficient pedal stroke you might otherwise want to fix. Second, the displayed value tends to sit nearer the top of the swing than a true instantaneous reading, so a quick glance during an effort makes you feel like you are holding more watts than you are. Over a whole interval the average is identical, but moment to moment, smoothing is quietly generous.
Real vs smoothed power: what changes on screen
Watch the same steady effort with smoothing off and the trainer number dances around from second to second, tracking the real rise and fall of your pedal stroke. Switch smoothing on and the display goes almost flat, parking close to your target while the underlying effort keeps varying just as much as before.
Crucially, when you average either version over half a minute the figures land in the same place. The averages match. The behaviour on screen does not.
| What you see | Smoothing OFF | Smoothing ON |
|---|---|---|
| On-screen number | Jumps a few watts every second | Sits almost dead flat |
| Feels like | Honest, slightly nervy | Calm and controlled |
| Instant reading vs truth | Accurate | Reads a touch high |
| Average over interval | Correct | Correct |
| Saved .fit file | Raw data | Raw data (unchanged) |
| Best for | Intervals, testing | Steady endurance |
The takeaway is simple: smoothing changes the experience of the ride, not the maths of your training. If you only ever look at post-ride analysis, you would never know it was on. If you pace by the on-screen number, it shapes every decision you make in real time.
How to turn power smoothing off
For honest intervals and any accuracy testing, I switch it off. Here is how, step by step.
- Wahoo (KICKR, KICKR Core, KICKR Snap): open the Wahoo app, tap your trainer, open its settings, find Power Smoothing and toggle it off. Because Wahoo smooths the broadcast, this carries into Zwift, TrainerRoad and MyWhoosh automatically.
- Zwift: Zwift does not add its own hardware smoothing, so there is nothing to disable inside it. If your numbers still look flat, the smoothing is coming from the trainer, so fix it in step 1.
- TrainerRoad: same story. TrainerRoad shows the raw broadcast, so any flatness is the trainer’s doing. Turn it off at the trainer.
- Garmin or Wahoo head unit: if you record on a head unit, set your power field to raw power rather than a 3s or 10s average so you see what is really happening.
When is power smoothing actually useful?
I am not anti-smoothing for everyone. On a long Zone 2 endurance ride, a calmer number genuinely helps some riders settle into a steady effort without chasing every flicker, and since the saved data is unaffected there is no real cost. New riders who find a jumping number stressful often stick with their turbo longer if it looks calm. That matters more than purist accuracy.
But for short intervals, sprints, micro-bursts and any kind of testing, switch it off. You want to see the truth of how fast your power rises and falls. This is the same reason I tell people to understand the difference between direct drive and wheel-on trainers before they buy: the more accurate the hardware, the more the smoothing setting actually matters.
How smoothing fits with your wider power picture
Smoothing is one piece of a bigger topic: trusting the watts your turbo reports. If you want the full picture of what those numbers mean and how reliable they are, read my guide on understanding power readings on your turbo trainer. It pairs well with knowing how training apps track your progress, because every TSS, FTP estimate and fitness chart is built from the raw data underneath the smoothed display, not the calm number on screen.
If you are setting up structured sessions, smoothing also interacts with resistance levels and ERG mode. In ERG the trainer holds your target watts for you, so an over-smoothed display can make a slightly soft ERG hold look perfect when it is not quite hitting the number. Switch smoothing off when you are dialling in a new workout so you can see how tightly your trainer is really holding each step.
My verdict
Power smoothing is a display convenience, not a cheat and not a problem, as long as you know it is on. It flatters your pacing and hides pedal-stroke roughness, but it never touches your saved data, so your training load and FTP are honest regardless. My rule is straightforward: off for intervals, testing and anyone learning to pedal smoothly; on only if a calmer number genuinely keeps you riding steady on long endurance days. Personally, I keep mine off and ride the real, slightly nervy number, because that is the one telling the truth.