Speed Sensor 2 measurements stopped early

I’ve been investigating this issue for the past two weeks, and I believe I’ve identified both the root cause and a workaround.

My hypothesis

1. Whenever an ANT+ or Bluetooth connection is active, the sensor stops standalone recording to prevent duplicate activities.

2. When the sensor is paired with a phone over Bluetooth, the Garmin Connect app periodically connects to the sensor to check for updates, synchronise data, etc (even in background, when application seems to be closed).

Effect: If your phone is near the sensor, Bluetooth wakes up every few minutes, so standalone recording is either interrupted or never starts.

What I did to confirm this

• Unpaired the sensor from my phone and removed it from the Garmin app.

• Rode many segments throughout the week.

• Re‑paired and reconnected my phone to the sensor.

• All activities from the past week synchronised correctly and appear to be recorded properly.

This doesn’t change the fact that the product software is poorly designed:

• It records every wheel movement, regardless of distance, with no configurable threshold, so I ended up with several 50–60 m “activities” just from moving my bike around the garage.

• When I stopped riding, the device closed the activity after a few minutes (apparently four) and started a new one when I set off again. The feature itself is useful, but there should be an adjustable time‑threshold setting.

Tested on software version 4.10 of the speed sensor 2.

I hope some other frustrated users will find this information useful :)