Monitor your speed as you ride with this easy-to-install wireless sensor. With no magnets or other exposed parts to line up, this sensor is easy to install, maintain and move between bikes. 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.