I used an Omron HR100C for a year and some until a few weeks ago when I got a Garmin. It was cheap ($31), effective and the batteries are user replaceable. It is one of the type with a chest strap and a wrist watch readout. I found that if you get a couple of inch long piece of split foam pipe insulation from Home Depot or wherever, the insulation will go around your bar and the watch will strap to it. I found that the readout on the watch was hard to see on my wrist and I also found (!!!) that I need to keep my hands on the bars, especially during those physically demanding moments that are exactly the times you may want to note your heart rate.