Buy what you can afford and need. Polar makes some of the best heart rate monitors out there that also include cyclometer features such as speed, cadence, and even power meter functions.\n\nCiclosport also makes a heart rate monitor that includes the cyclometer functions, but no power meter functionality.\n\nIf you really have the serious bling, you could go for an SRM powermeter. That will have the cyclometer, power meter, and heart rate all wrapped up into one. It's also the choice of most pros out there.