Seriously, this is really starting to piss me off...I've never had a problem changing a tube before.
I've had my tires blow out 3 times in a row. It seems that the tubes I am using always give up at the stem (presta). They sit fine for a while, then randomly explode. Checked the tires for thorns and things several times, the rim strip looks alright, and the wheel doesn't have any rough edges near the hole where the stem goes through.
I don't think the tubes are bad because I bought them at different times. The only thing I can think of is that the bead of the tires is really loose. I can change a tire with no effort without tire levers (I don't think that there are too many miles, maybe <1k). When I mount it, it looks fine, however.
Please help me out!