My wife and I ride a tandem and her watch picked up my chest strap. I am only guessing it is because I am upright and her handle bars are closer to my chest strap then my hands on the handle bars are. The reason why I give it my recommendation is because it was at a good value Just not good for tandem cycling. I like the way you can tap the watch to chest strap to change functions. it beats taking my hands off my handle bars while trying to push buttons. Its efficient. A friend told me to purchase two different brands of heart rate monitors and it should work. Two stars because it did not work for what I needed it for. However if you don't get to close to someone with the same watch you will have no problem.