Monitor your speed as you ride with Garmin's easy-to-install wireless sensor. The speed sensor attaches to the hub of either wheel and self-calibrates with your Garmin device to give you accurate speed and distance at all times, including indoors on the trainer. Simply attach the sensor and ride. With no magnets or other exposed parts to line up, this sensor is easy to install, maintain, and move between bikes.

Stay aware of approaching cars with Varia RTL515 rearview radar. It pairs with your Edge bike computer or compatible smartphone to alert you of vehicles approaching from behind up to 153 yards (140 meters) away. When used with your compatible smartphone, the Varia app uses bold graphics — plus tone and vibration alerts — to indicate the position and speed of approaching vehicles. MAXIMUM AWARENESS - Varia RTL515 rearview radar provides visual and audible alerts for vehicles approaching from behind up to 153 yards (140 meters) away. MULTIPLE PAIRING OPTIONS - This radar works seamlessly with your Edge bike computer or compatible smartphone as well as select Garmin wearables or the optional radar display unit. WORKS WITH THE VARIA APP - This smartphone app helps you increase your awareness by providing graphics — plus tone and vibration alerts — that indicate the position and speed of approaching cars. THIRD-PARTY APP COMPATIBLE - When used with a compatible smartphone, Varia radar integrates with your favorite apps, such as Ride with GPS to overlay your maps with rearview radar alerts. SUPERIOR VISIBILITY - Alert motorists to your presence as soon as possible with daylight visibility up to 1 mile. COMPACT DESIGN - Easily mount this sleek, compact device on the seatpost of almost any road-use bicycle. The vertical design allows for better leg clearance and a perfectly comfortable ride. PELOTON MODE - Varia RTL515 features multiple modes, including peloton mode, which provides a low-intensity flash that is kind to other cyclists’ eyes when riding in a group. BATTERY LIFE - Time spent charging is not as good as time spent riding. Get up to 16 hours of battery life in day flash mode and up to 6 hours in solid mode. Physical Specifications - Dimensions: 3.9” x 0.8” x 1.6" (98.6 x 19.7 x 39.6 mm) - Weight: 2.5 oz (71.0 g) - Modes: solid, peloton, night flash, day flash - Lumens: 20 solid, 8 peloton, 29 night flash, 65 day flash - Battery life: 6 hours solid, 8 hours peloton, 6 hours night flash, 16 hours day flash - ANT+: Yes - BLE: Yes - Water rating: IPX7 - Viewing angle: 220° In the box: - Varia RTL515 - Mounting Kit - Cables - Documentation