I use a Garmin GPS for monitoring speed and distance, and there are a lot of other things you can keep track of as well. One of my best investments :)
Another best investment: My $17 stethoscope. You can use it for a lot more than measuring heart rate, and they always work whereas the electronic systems can be iffy. I've used both at vet checks, and the electronic ones are great when they're working and terrible when they're not. After a practicing a few times with a stethoscope, I've got it down pretty well. Plus, I can throw a stethoscope into my saddle bag easily and compactly. With the system you posted, you're going to have to dismount to take the heart rate anyway. I would recommend saving the money and getting a Polar monitor that you can use while riding. You can also track speed on some of them.