An all purpose heart rate monitor. One of the best ways that you can get more out of training rides and to raise your general fitness level is by working with your heart rate. Tracks your heart rate and calories burned in real time while you exercise. Being both ANT+ and Bluetooth capable, it allows your to connect to both smartphones and GPS watches. Equipped with two LED lights, one to show when it is connected and the second to show that it is detecting your heart rate. It works seamlessly with over 50 iPhone Apps including Runkeeper, Strava, MapMyFitness, and Cyclemeter/Runmeter.
If you want heart-rate data but don't like wearing chest straps, then the Wahoo Tickr Fit could be a good solution. The small unit wraps around your arm and connects easily to bike computers and smartphones on ANT+ and Bluetooth. The data tracks well against a traditional chest strap.