I did a search on google and this forum, couldn't find a conclusive answer. I'm using a polar cs200, am 20 years old, and weigh 175 lb. I'm asking because I can hit 207~ bpm without too much difficulty, and I feel like i can hit 215 or so.
As a rule of thumb your maximal heart rate is 220 minus age. But as you´ve already discovered that all people fit into that formula. There is a standard deviation which means that "200-240 minus age" would be the normal range for maximal heart rate. So you are quite normal (correct me I´m wrong...
If you want to test your maximal heart rate it is very important that you are motivated, because when you are above 95% it is all about being dedicated to the project.
It is a very good idea to use some kind of a power meter so that you can make small increments during the test. I will suggest you increase the resistance with about 10W pr 15 seconds. This is done to make sure that you are not spending to long time on the test but still long enough to reach your maximal oxygen consumption. If you start out to hard or make too big increments in watts, you will spent your energy going anaerobic to early. Thus, you will get exhausted before you reach your maximal heart rate.
With this test setup you will suffer the last 2-4 minutes.
Remember, as already mentioned, some people can´t get motivated enough in a testing situation so they will reach higher heart rate during races.