Does the SDM remember your calibrated settings after you've changed batteries? I calibrated mine at the track about a month ago and 2 battery changes later it's giving me weird readings: 13 minute miles for example.
Anyone any ideas?
(By the way, when I first went to calibrate the SDM, instead of reading 400m after one lap it read 360m. Which is only 90% accurate (I think!) and over the course of a three hour run the readings would be pretty out.)