I took a ride today with my new Sigma BC1909 HR computer. It has a chest strap and it was able to measure my heart rate to some degree. The HR monitor seems to reflect my heart rate, but at a delayed pace. It does not seem to be entirely accurate or very responsive, but it does give me a general trend as far as my heart rate. For example, the number displayed on the HR monitor would trend upward as I exerted myself going up a hill, then it would trend downward as I went downhill. So, I have found a HR monitor that works to some extent. It may not be entirely accurate, but it does give me some idea of what is going on with my HR. I suppose the HR monitor cannot be more responsive or accurate due to my atrial fib.