Sometimes my cadence isn't measured. The computer will just read "0;" but sometimes it will be measured. I've placed the sensor on the frame to be as closest to the magnet inside my crank arm as possible. I'll post a picture once I get my camera back, but in the meantime, does anyone have any suggestions or questions I can answer in order to fix this? Thanks.
Mine does the same thing on probably every third ride. I "cycle " it through all the settings and it kick starts back to reading again. I usually catch it in time since I look at it often. I just add 1/4 mile or so to the total ride at the end. It has a two year warranty, but you have to bring the unit in with the bike to the shop before they will exchange it. PITA.
Current Cannondales: 1999 F400, 2007 Road Warrior 800 . Gone, but not forgotten: 1991 SC600, 1992 M700, 1997 R500t.
Not exactly the same problem - but likely the same solution: get a fresh battery! I started having the same flaky performance with mine about two weeks after installing it though just with displaying speed. After re-reading the installation instructions I noticed a tiny blurb about "battery life '. It basically says - don't expect much from the factory battery. Got a new one for three bucks and have been more than happy since. Give it a try!