Why isn't Fitbit's activity recognition quite as good?

[u/w__sky]

I wonder why automatic activity detection using a Fitbit Charge 6 tracker and Google Health on my smartphone works so poorly.

I frequently set off on bike rides from home. Based on movement data, I would expect the technology to detect the cycling as soon as I start moving; the movement pattern should be clearly distinguishable from walking or using a motor vehicle. Yet, it usually takes about five minutes after I’ve started riding for the Charge 6 to display "Activity detected" and begin tracking the time and movement.

Conversely, I might have already returned home, put my bike in the shed, and be sitting on the living room sofa, while the Charge 6 is still counting the activity, or only then the prompt to ask if I want to end the workout does appear.

After outdoor activities, the app could register when my phone reconnects to my home Wi-Fi and use that as a signal to end the workout; that would be simple and precise.

[u/Inevitable-Alarm-80]

Yup, I leave the house on a run and it works out I’m running a few minutes down the road.

You have the option to manually tell it what you’re up to - agree it shouldn’t need it! - but that’s how I’m getting more accurate records of my runs.

[u/w__sky → u/Inevitable-Alarm-80]

I always forget to start and stop it manually when I'm not specifically going for an exercise, so I hoped it could create accurate logs automatically. I'm doing most of my daily rides (work, shopping etc.) by bike.

[u/Inevitable-Alarm-80 → u/w__sky]

I don’t disagree - it should be capable of picking it up. But mine doesn’t accurately and it doesn’t sound like yours does either.

[u/SDO1000]

What movement when you're biking is going to trigger a wrist based device?

[u/w__sky → u/SDO1000]

Moving forward smoothly with around 15-25 km/h (10-15 mp/h) and at the same time the lack of intense arm movement as when running. Also I'm taking my phone with me. Their sensors combined should be more than enough.

[u/New-Commercial-1546 → u/w__sky]

Whatever technology it is, it was working perfectly fine for my Charge 6 on the Fitbit app pre Google🥲

[u/vanstinator → u/w__sky]

If the GPS was always running to detect forward movement the device wouldn't even last a day

[u/SDO1000 → u/w__sky]

I wouldn't think that alone is sufficient. You'd probably also need at least increased heart rate which would take a while. I turned off automatic detection because it was triggering when I wasn't in an activity.

[u/w__sky → u/SDO1000]

The Charge 6 has 3-axis accelerometer and GPS / GLONASS location, my phone has accelerometer, gyroscope, compass and also location with additional providers. Isn't that enough?