We haven't had a 'stupidest thing I've done on my bike' thread for a while. On Sunday I fitted my VDO heart rate sensor around my chest and set off for a ride. As I climbed onto my MTB I noted I was registering about 80BPM. So I started up the climb that is my gateway into the Surrey Hills. The plan was to go slowly and avoid setting off the nagging cough that's been annoying me the last week or so. Halfway up the hill the HRM was climbing steadily and I was feeling fine. But to my surprise the numbers just kept soaring rather than starting to level out. It wasn't long before I busted through my previously recorded max HR. Yet I wasn't really exerting myself. All I could think was that I was still ill and this had to account for the soaring heart rate showing on my cycle computer. So I slowed down slightly, however the numbers kept climbing. Soon I was up to 216BPM (20 above my usual max). At the top of the hill I stopped. Something must be wrong. Then I realised I was looking at my VDO altimeter and the heart rate monitor was lying at home. I'm such an idiot. Anyone else?