I have a CatEye HR-10 heart rate monitor, a few months old, which is a useful bit of kit. On Friday I strapped it on, and it kept reading over 200 bpm plus en route to Summer Lightning. For en route, read in the car, quite relaxed as I like driving and I know the way very well. Could have been interference from car electronics, except problem persisted throughout ride! Normally when riding I know when I am hitting the 180+ mark as that is when the legs are burning, I am puffing and I have run out of gears . Same problem again today,lowest reading 197 even though I was sitting at rest at the time nowhere near any electrical / electronic gadgets. Huh? Either I have a serious cardiac problem, or my monitor is playing silly B's. So I check it later by the traditional, take-own-pulse-while-timing-minutes method. Monitor is out by 20-30bpm so all data about time in and out of optimum zone is bad data! Anyone else had this problem, or any ideas what I do about it?