I've just purchased new non-magnet cadence and speed sensor twin pack to replace my GSC10 which stopped working, to use with an Edge 500 and I've got a bit of an odd problem happening.
If I pair only the cadence sensor and rotate the cranks then I see a reading for cadence on my Edge display, if I pair only the speed sensor then I see a speed reading when I spin the back wheel, now if I choose to pair as "cadence and speed sensor" (not cad/spd option) then when I rotate the cranks I get a reading for cadence and also a speed reading but the bike is stationary. I'm rotating the cranks backwards but I don't think this should be an issue. It would appear that the Edge is using the cadence sensor output to calculate speed readings!!!
For the time being I've removed the speed sensor and am going to use the GPS readings, which will give me cadence and speed which is the end goal but I would prefer not to take this route in the long term.
My Edge 500 firmware is up to date, v3.30 I think, according Garmin Express
Has anybody else had experience of this problem?