I'm really happy with my Mio Global Alpha. No chest strap and doesn't rely on electrical contacts. It is worn like a wrist watch and uses light to detect the pulse. I've tested it against $20,000 ambulance monitors and against the monitoring equipment in our cardiac rehab department. It is spot on and I've never lost signal nor had any glitches in the data. I've worn it on several very sub-freezing rides and in the gym. Nothing but praise so far.