Yes, a Garmin speed sensor will override the speed and distance data provided by GPS on your Garmin device when it is connected and used during an outdoor timed activity. This ensures more accurate and consistent data, particularly in challenging environments where GPS signals might be less reliable.
When paired with a compatible Garmin device, dedicated speed sensors become the primary source for calculating your current speed and the total distance traveled during an activity. This override mechanism is designed to provide you with the most precise data possible for your cycling or running performance.
Why Speed Sensors Take Priority Over GPS
While GPS is excellent for tracking your route and overall location, it can have limitations when it comes to instantaneous speed and precise distance measurement. Factors like satellite signal strength, dense tree cover, urban canyons, tunnels, or even a slight delay in GPS signal updates can affect accuracy.
Dedicated speed sensors, on the other hand, measure wheel rotations or direct movement, providing immediate and highly consistent data. This direct measurement method offers several advantages:
- Enhanced Accuracy: Speed sensors typically provide more precise speed and distance readings, especially for short bursts of speed, sudden changes, or specific segments.
- Consistent Data: They are not affected by GPS signal fluctuations, ensuring a smoother and more reliable data stream.
- Indoor Use: A speed sensor allows you to accurately track speed and distance even when cycling indoors on a trainer, where GPS is unavailable.
- Instantaneous Readings: Speed sensors provide immediate feedback on your speed without the slight lag sometimes associated with GPS.
Which Garmin Sensors Override GPS?
Garmin has developed specific speed sensors designed to integrate seamlessly with their devices and take precedence over GPS data. The following Garmin speed sensors are known to override GPS for speed and distance data:
- Garmin Speed/Cadence Sensor (GSC10): An older, combined sensor that measures both speed and pedal cadence.
- Garmin Bike Speed Sensor (BSS): A dedicated speed-only sensor.
- Garmin Speed Sensor 2: The newer generation of Garmin's dedicated speed sensor.
When Does the Override Occur?
The override happens specifically when a compatible Garmin speed sensor is connected and actively used during an outdoor timed activity. This means if you are just navigating without recording an activity, your device might still rely primarily on GPS for speed display. However, when you hit 'start' to record a ride, run, or other timed activity, the sensor's data will be prioritized.
GPS vs. Speed Sensor Data Overview
To illustrate the differences and why the override is beneficial, consider the following comparison:
| Feature | GPS Data | Speed Sensor Data |
|---|---|---|
| Primary Use | Overall location, route tracking | Precise speed, distance, and consistency |
| Accuracy | Can vary with signal, environmental factors | High, consistent, independent of signal |
| Instant Speed | Can have slight lag, smoothed data | Real-time, highly responsive |
| Distance | Calculated from position changes | Calculated from wheel rotations (highly accurate) |
| Indoor Use | Not available | Fully functional (e.g., on trainers) |
| Override | Overridden by sensor when connected during activity | Overrides GPS for speed/distance when connected |
| Dependence | Relies on satellite signal | Relies on physical wheel rotation |
By leveraging a Garmin speed sensor, athletes can gain a more accurate and robust dataset for their training and performance analysis, ensuring that their speed and distance metrics are as precise as possible, regardless of external conditions.
