I haven't searched the entire Edge 520 forum yet; however, I have found it strange that on my road bike - Power2Max power meter which includes cadence data as well - shows a cadence of 60 and fluctuating up and down while I'm stopped. I'll be pedaling at 90 rpm and it shows 120, fluctuating around to various numbers obviously skewing my data. Not a huge deal breaker because i'm still recovering from hip surgery but would like to figure it out.
I used the same garmin 520 on my mountain bike today. I have no sensors on that bike at all and it was showing cadence numbers on my garmin 520 in the same manner...
Which led me to believe it's not the power meter dying at all... it's the garmin unit.
Any ideas?