Today's heart-rate monitors are pretty amazing. We recommend the wireless type because they're accurate and user friendly. They come in two pieces, a belt that's worn around your chest (the transmitter) and a watch (the receiver) that's worn around your wrist (or placed on the handlebar).
To use a wireless heart-rate monitor, you simply wet the surfaces of the transmitters on the belt and wrap the belt around your chest. Attach the watch to your wrist or bars and you're wired for heart rate. In use, the chest transmitter picks up your heart beat and sends a signal to the receiver on your wrist, which displays your current pulse. So, you now know exactly how hard your heart is working at all times.
The great thing about heart-rate monitors is that they help gauge one's fitness so you can plan your training based on good data about your current fitness level. They also allow you to accurately gauge your effort so you can make sure you're working hard enough and so that you can ensure you're resting, if you're in recovery mode after too long or hard a ride.
A myriad of features are available in modern heart-rate monitors, such as memory functions and downloadability. Which model you use should be based on how much you wish to spend and what features you think you'll use. Some of the most basic HRMs, which only provide a readout of heart rate, are very popular exactly because they are so simple (also, the least expensive). There are no complicated features to confuse you.
If you'd like a more features-laden model, nice options to have include average heart rate, so you can tell your heart-rate level during a workout; programmable alarms that sound if you're going too easy and/or too hard; and memory, which lets you play back a ride and see your pulse's peaks and valleys. There are also HRMs that are part of a full-function cyclo-computer, which means that besides pulse, you get a readout of all your favorite ride data, too, such as mph, average and top speed, distance, etc.
If you're interested in this important training tool, come in and we can demonstrate the latest models. Keep in mind that some even double as wristwatches so you can use them off the bike, too.