The speed sensor 2 attaches to the hub of either wheel. You can set up wheel size in our Garmin connect online community or self-calibrate with an edge cycling computer or compatible Garmin device. Once set up, you’ll get accurate speed and distance at all times — even without a head unit. Ant+ connectivity and Bluetooth Low energy technology Let you sync to Garmin Connect and other training apps, compatible devices and fitness equipment for better data when you ride indoors and outdoors. The odometer feature tracks your distance to help plan for bicycle maintenance.