This cheap and cheerful HRM from Wiggle's in-house Lifeline brand does the job for a very attractive price. It's a traditional chest strap monitor that will pair with your ANT+ and Bluetooth Smart devices, with an adjustable belt to suit all chest sizes.
Simply, a heart rate monitor reads how fast your heart is beating and expresses this in beats per minute . For cyclists, it's useful to know how fast our hearts are beating to determine what effort we're putting in, and whether we need to back off or up the intensity. After you've set your training zones you'll know if you're working at the right level according to what numbers your heart rate monitor is spitting out.
Fitter people are able to pump blood around their body more efficiently, so will have a lower resting heart rate. A normal resting heart rate for adults is between 60-100 BPM, while for professional endurance cyclists it can be much lower than that. Five-time Tour de France champion Miguel Induráin reportedly had a resting heart rate of just 28 BPM!