I had a Firstgear Silverstone tank bag that had super strong magnets along the entire bottom. It ruined 2 debit cards before I figured it out. I now use an icon tankbag that only has magnets on the 4 "wings" and my cards seem safe in this one.
occasionally mary starts the microwave and i piss my pants and forget my name...........
that's a great movie.
I've had my wallet in my tank bag and did not have an issue with the credit card. But I only did it once because I thought to myself as I was riding what if I'm at a stop light and someone just grabs the bag right off the bike and takes off. Odds are extremely low I'm sure but I've never put my wallet in there since.